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In all cases we have film ed the best available copy. University Microfilms International 300 N. ZEEB RD., ANN ARBOR, Ml 48106 8126477 B u c k l e r , W il l ia m R o g e r RATES A N D IM P L IC A T IO N S O F BLUFF RECESSIO N A LO N G T H E LA K E M IC H IG A N SHO REZO NE O F M IC H IG A N A N D W ISC O N SIN Michigan State University University Microfilms International P h.D . 300 N. Zeeb Road, Ann Arbor, M I 48106 1981 PLEASE NOTE: In all cases this material has been filmed in the best possible way from the available copy. Problems encountered with this document have been identified here with a check mark V 1. Glossy photographs or pages______ 2. Colored illustrations, paper or print_____ 3. Photographs with dark background 4. Illustrations are poor copy______ 5. Pages with black marks, not original copy 6. Print shows through as there is text on both sides of page______ 7. Indistinct, broken or small print on several pages 8. Print exceeds margin requirements _ _ _ 9. 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Curling and wrinkled pages______ Other_____________________________________________________________________ University Microfilms International RATES AND IMPLICATIONS OF BLUFF RECESSION ALONG THE LAKE MICHIGAN SHOREZONE OF MICHIGAN AND WISCONSIN By W illia m Roger Buckler A DISSERTATION Submitted to Michigan State U n iv e rs ity in p a r t ia l f u l f i l l m e n t o f the requirements f o r the degree o f DOCTOR OF PHILOSOPHY Department o f Geography 1981 ABSTRACT RATES AND IMPLICATIONS OF BLUFF RECESSION ALONG THE LAKE MICHIGAN SHOREZONE OF MICHIGAN AND WISCONSIN By W illia m Roger Buckler Long-term Lake Michigan b l u f f c re s t recession rates a t 118 widespread lo c a tio n s in Michigan and Wisconsin are determined by c o n tra s tin g recent f i e l d measurements w ith those from 19th century government land o f f ic e surveys. These rates are evaluated s p a t ia l ly and re la te d to selected shorezone c h a r a c te r is tic s . In a d d itio n , lake le v e l records and a e ria l photographic data are compared to determine recent recession rates a t c lo s e ly spaced case study s ite s in Shoreham, Michigan, and Kenosha County, Wisconsin; these provide a basis f o r p r e d ic tin g fu tu re b l u f f c re s t p o s itio n s . Long-term recession data in d ic a te t h a t : (1) Sites and segments on both sides o f Lake Michigan d is p la y wide v a r i a b i l i t y in b l u f f l in e changes. (2) B l u f f c re s t recession along opposite shores is s t a t i s t i c a l l y s im ila r . (3) Non-sand dune b lu f f s along the southern shore o f each s ta te tend to experience r e l a t i v e l y rapid r e t r e a t . (4) B lu ffs in southern Wisconsin recede a t rates s i g n i f i c a n t l y higher than those in the north. Findings based on the 118 s ite s also reveal t h a t : (1) B lu ffs o f dune sand tend to recede a t s i g n i f i c a n t l y lower long-term rates than b lu f f s composed o f non-dune sediments; apparently these lower values r e s u l t from dune a c cretio n during periods o f low lake le v e l. (2) V a ria tio n s in long-term recession rates o f b lu f f s composed o f non-eolian m a te ria l are not d i r e c t l y re la te d to d iffe re n c e s in sediment W illiam Roger Buckler type o r arrangement. (3) Differences in sho re line o r ie n ta tio n and fetch appear to in flu e n c e rates o f r e t r e a t . (4) Long-term recession rates do not vary d i r e c t l y w ith changes in b l u f f height or ground water a c t i v i t y even though the l a t t e r may c o n trib u te to slope i n s t a b i l i t y , e s p e c ia lly on high b l u f f s . Results o f the two case studies disclo se t h a t : (1) Modern recession rates vary according to the in te r v a l between measurements. (2) The highest rates tend to occur w it h in periods th a t contain the greatest percentage o f years when lake le v e ls are high. (3) Modern rates are not s im ila r to long-term r e tr e a t values, a con d itio n la r g e ly a t t r ib u t a b le to in cre asing numbers o f shore p ro te c tio n s tru ctu re s th a t may accelerate b l u f f r e t r e a t in some places. ACKNOWLEDGEMENTS Numerous in d iv id u a ls assisted me in the successful completion o f t h is d is s e r ta tio n . Two people are e s p e c ia lly noteworthy. I am extremely g ra te fu l to Dr. Harold A. "Duke" W inters, my major a d viso r, who somehow endured through i t a l l . His guidance, patience, time (measured on the geologic s c a le ), c o n s tru ctive c r i t i c i s m , " b e tte r words," and in s tr u c tio n a l methods are g re a tly appreciated. (But a kick in the pants o c ca sio n a lly would not have h u rt e i t h e r . ) I am a b e tte r geographer because o f him. Without the f u l l support o f my w ife , Ruth Ann, the study would be u n fin ish e d . She was a top notch f i e l d a s s is ta n t and was uncomplaining (as long as I supplied paperback books, d a ily chocolate m alts, and at le a s t one decent meal a week) when I wished to repeat measurements, absentmindedly l e f t equipment at previous s it e s , or took too long completing f i e l d notes. She shared in my t r i a l s and t r i b u l a t i o n s throughout the l a s t f i v e years and she p a t ie n tly accepted my long hours in the f i e l d and at the o f f ic e . I am indebted to the fo llo w in g fa c u lt y members who g ra cio u sly served on my doctoral committee and gave f r e e ly o f t h e i r time and counsel: Dr. Jay R. Harman and Dr. Jack F. Williams o f the Department o f Geography and Dr. Delbert L. Mokma o f the Department o f Crop and Soil Sciences. I also wish to thank Dr. Gary Lemme o f the Department o f Crop and Soil Sciences and Dr. Ger S chultink o f the Department o f Resource Development f o r c r i t i c a l l y reviewing the f in a l manuscript and serving on my defense committee. Special praise goes to my fa m ily who may not always have known what I was doing but were nevertheless supportive in many and varied ways: To my parents, Roger and M a rjo rie , who came to the rescue when expensive equipment was u rg e n tly needed and a t r a i l e r and la rg e r car desired; u n fo rtu n a te ly , the auto was returned in less than p e rfe c t c o n d itio n when my mind was on Lake Michigan but the car was being driven in East Lansing. To Mom, who re lie v e d my stre ss by o b lig in g ly doing a l l the worrying f o r me. To my broth e r and s i s t e r - i n - law, David and Susan, who always cheered me along. Dave's comment when a t the lakeshore w ith me: climb up and down those b lu ffs '." I 'll never fo rg e t "You mean you a c tu a lly And to my in -la w s , B i l l and Barbara, f o r never asking when I was going to f in is h . Other people should be applauded. Thomas Krabacher and Ralph DeVitto assisted me in f i e l d surveys and Michael Lipsey in the f in a l map reproductions. M artin Jannereth and Fred C lin to n o f the Michigan Department o f Natural Resources, Charles Hess, Joan Gasperow, and Glen Olsen o f the Wisconsin Department o f Natural Resources, Roger Springman o f the Wisconsin Geological and Natural H is to ry Survey, Larry Hiipakka o f the North Central D iv isio n o f the U.S. Army Corps o f Engineers, Tim Monteith o f the Great Lakes Basin Commission, and Joan McConley and Joel Young o f the Wisconsin and Michigan o f f i c e s , re s p e c tiv e ly , o f the USDA A g r ic u ltu ra l S t a b iliz a t io n and Conservation Service were most cooperative in p roviding data and/or photographs. Many land surveyors, re g is te rs o f deeds, and road commissioners and engineers were generous in sharing corner lo c a tio n s and e x is tin g p roperty surveys w ith me. In Michigan some o f these people are: W illia m J. DeVette and Charles F, Lewandaski o f Muskegon, Anthony S la w in s ki, Richard L. Hayes, and Dorthy Konicki o f Manistee, Harold R. Bruning and G.H. "Pat" Johnson o f Beulah, W illiam R. By! , and Russell E. Stadt o f Grand Rapids, Glenn DeLaMater o f Traverse C ity , D.H. Dreher o f N ile s , James Evans and L e s lie Kolk o f Hart, Robert A. G r i f f i n o f Baldwin, John K i s t l e r o f Grand Haven, Sammy Barnett and Mary G. Kolaski o f Ludington, Helen Korson o f Lei and, Mark Smith o f Paw Paw, James Richardson o f Benton Harbor, Donald A. Ratekin o f Allegan, James L. Halfacre o f Jackson, Theodore H. Weinert o f Suttons Bay, and G.L. Nightman o f St. Joseph. In Wisconsin, J e f f Add'e, Warren Draves, and David Oblack o f S tu rte v a n t, Joe McGuarin o f Racine, Robert Johanning o f Sheboygan, Thomas Genske o f Port Washington, and the personnel a t the Southeastern Wisconsin Regional Planning Commission in Waukasha were most h e lp f u l. Shorezone residents were the source o f much useful in fo rm a tio n . Overwhelmingly they were f r i e n d ly and cooperative (even the Wisconsin lakeshore farmer who, fo llo w in g the shearing o f my out o f con tro l beard, said I looked a "damn s ig h t b e tte r" w ith o u t i t than w ith i t ) . M e rito rio u s awards go to W illia m Gibbs and Donna Asselin o f Shoreham, Michigan, Genevieve Rae Hahne o f St. Joseph, Michigan, L.D. Huffman o f Wyoming, Michigan, Marie Rowland o f Racine, Wisconsin, M a rjo rie Hubbard o f G rafton, Wisconsin, and the Robert R u lo ff fa m ily o f Sheboygan County, Wisconsin, the l a t t e r i n v i t i n g Ruth and me over one evening fo r conversation and several b o ttle s o f wine; our survey lin e s were none too s t r a i g h t the next morning. iv Susan McMahon's fla s h in g fin g e rs typed the f in a l manuscript. Her e f f ic ie n c y , cheerfulness, accuracy, l a s t minute e d it in g , and frie n d s h ip (even a f t e r t h i s ) are a p p re c ia tiv e ly acknowledged. Special t r i b u t e must be extended to Professor Robert "Doc" Goodman o f Wayne State U n iv e rs ity . His world regional geography course, taken as a freshman, e x cite d me to the p o in t th a t I , fo r b e tte r o r worse, declared geography as my professional p u rs u it. In one or more ways fo u r in d iv id u a ls have e s p e c ia lly influenced my career: Duke Winters and Jay Harman o f Michigan State U n iv e rs ity and Bob Goodman and Bryan Thompson o f Wayne State U n iv e rs ity . I only hope th a t I can take the best a t tr ib u t e s o f each and be h a lf as good. To a l l those unmentioned but s t i l l remembered in d iv id u a ls and organizations th a t made t h is document p ossible: THANKS! And to DPL - - a decade ago you shelved a b o t t le o f R & R from me to be opened when we both fin is h e d th is " f o o lis h " undertaking. am looking forward to sharing i t w ith a r ic h and rare fr ie n d in the not to d is ta n t fu tu re . AMEN and THE END! (Duke, there are no " b e tte r w ords.") v I TABLE OF CONTENTS Page LIST OF TABLES............................................................................................................. ix LIST OF FIGURES......................................................................................................... xi Chapter 1 Chapter 2 Chapter 3 OBJECTIVES, METHODOLOGY AND LITERATURE REVIEW ..................... 1 In tro d u c tio n ................................................................................. Objectives ..................................................................................... Study Areas..................................................................................... Basic C r i t e r i a ............................................................................. D escription and Use o f the General Land O ffic e Surveys Surveying Procedures ............................................................. . S ite S e l e c t i o n ............................................................................. S ite Observations......................................................................... L ite r a tu r e Review......................................................................... J u s t i f i c a t io n and A p p l i c a b i l i t y ............................................. 1 2 3 3 5 6 8 8 10 21 SHOREZONE CHARACTERISTICS AND CONDITIONS FAVORING SHOREZONE EROSION ......................................................... 24 In tro d u c tio n ................................................................................. Shorezone Terminology................................................................. Shoreland Physiography ............................................................. Shore!and B l u f f s ..................................................................... Beaches..................................................................................... Longshore Sand B a r s ............................................................. Shorezone I c e ......................................................................... Lake Level V a r ia tio n s ................................................................. Winds, Waves, and Currents ..................................................... S t o r m s ............................................................................................. Summary............................................................................................. 24 24 26 26 27 28 29 30 33 34 36 SITE CHARACTERISTICS, RATES AND SPATIALVARIATIONS OF LONG-TERM BLUFF RECESSION, AND RELATIONSHIP OF SELECTED VARIABLES TO BLUFF RETREAT......................................... 38 In tro d u c tio n ................................................................................. Long-Term and Short-Term B l u f f Recession..................... Spacing and Point Nature o f the S i t e s ......................... S ite C h a r a c t e r i s t i c s ................................................................. Rates o f Long-Term B l u f f Line Change................................. 38 38 39 41 42 vi Page Spatial V a ria tio n in B l u f f Line Change ............................ Representative Areas o f High B l u f f Recession. . . . Wisconsin............................................................................ M ic h ig a n ............................................................................ Representative Areas o f Low B l u f f Recession . . . . Wisconsin............................................................................ M ic h ig a n ............................................................................ The R e lationship o f Sand Dunes and B lu f f Recession . . R elationship o f B l u f f Recession to Other Selected V a ria b le s .................................................................... Ground Water............................................................................. B l u f f H eight............................................................................. Shorezone P rotection Structures .................................... Shoreline O rie n ta tio n ........................................................ Beach W i d t h ............................................................................. Im p lic a tio n o f Other Factors............................................ Assessment o f Factors In flu e n cin g Large-Scale Patterns in B l u f f Recession Rates .................................... Summary............................................................................................. Chapter 4 MODERN RATES OF BLUFF RECESSION AND THEIR FUTURE IMPLICATIONS: TWO CASE STUDIES................................................ 42 47 47 49 54 54 54 61 77 77 79 80 81 83 83 87 89 91 I n t r o d u c t i o n .................................................................... 91 Determination o f Recession Rates ........................................ 91 The Shoreham Case Study............................................ 91 C h a ra c te ris tic s ..................................................................... 94 B l u f f Recession: 1938 to 1977........................................ 98 110 The Northern Kenosha County Case Study ............................ 110 C h a ra c te ris tic s .................................................................... B l u f f Recession: 1941 to 1975........................................ 115 Future Rates o f B l u f f Recession................................................. 126 Methodology f o r P re d ictin g Future B lu f f Crest P o s itio n s ......................................................................... 129 Period o f Record and Data B a s e ..................................... 129 Representative B l u f f Retreat Value f o r the Period o f Record................................................. 130 Lake Level Factor and P re d ictio n o f Future B l u f f R e tre a t......................................................... 131 B l u f f Crest Positions in the Next Century: Two Case Study P r e d i c t i o n s ................................................. 134 Shoreham................................................................................. 134 Northern Kenosha County..................................................... 135 Chapter 5 SUMMARY AND CONCLUSIONS ................................................................. 138 Suggestions f o r Future Research................................................. 140 v ii Page APPENDIX A SHOREZONE TERMINOLOGY USED IN THIS STUDY..................................... 142 APPENDIX B SELECTED CHARACTERISTICS OF THE WISCONSIN AND MICHIGAN STUDY SITES .................................................................. 147 APPENDIX C LONG-TERM BLUFF LINE CHANGES AND LOCATIONS OF THE WISCONSIN AND MICHIGAN STUDYSITES ................................... 168 LIST OFREFERENCES.......................................................................................................... 189 vi ii LIST OF TABLES Page Table 1. 2. V a ria tio n in long-term average annual rates o f b l u f f l in e change a t the Wisconsin and Michigan study s ite s 43 Results o f Student's t te s ts in d ic a tin g th a t s t a t i s t i c a l l y there is no s ig n if i c a n t d iffe re n c e (a t the .05 s ig n ific a n c e le v e l) in the o v e ra ll rates o f long-term average annual b l u f f c re s t recession between the Wisconsin and Michigan study s ite s . . . 44 3. Results o f Student's t te s ts in d ic a tin g th a t s t a t i s t i c a l l y there is a s ig n i f ic a n t d iffe re n c e (a t the .05 s ig n ific a n c e le v e l) in the long-term average annual b l u f f c re s t recession rates between the Wisconsin s ite s south o f Port Washington (Ozaukee County) and those north o f the c i t y ...................................... 46 4. Results o f Student's t_ te s ts in d ic a tin g th a t s t a t i s t i c a l l y there is no s ig n if ic a n t d iffe re n c e ( a t the .05 s ig n ific a n c e le v e l) in the o v e ra ll rates o f long-term average annual recession between Wisconsin and Michigan non-sand dune b l u f f s ite s ............................................. 65 5. Comparison o f long-term average annual rates o f recession between b lu f f s encompassing dune sand and b lu f f s composed o f non-dune sediments......................................................66 6. Results o f Student's t_ te s ts in d ic a tin g a s t a t i s t i c a l l y s ig n i f i c a n t d iffe re n c e ( a t the .05 s ig n ific a n c e le v e l) in long-term average annual b l u f f l in e recession rates along the combined Michigan and Wisconsin study areas between b lu f f s encompassing dune sand and b lu f f s composed o f nonsand dune sediments 67 Results o f Student's t_ te s ts in d ic a tin g a s t a t i s t i c a l l y s i g n i f i c a n t d iffe re n c e ( a t the .05 s ig n ific a n c e l e v e l) in long-term average annual b l u f f l in e recession rates along the Michigan study area between b lu f f s encompassing dune sand and b lu f f s composed o f non-sand dune sediments ............................. 68 7. ix Page Table 8. Results o f Student's t_ te s ts in d ic a tin g a s t a t i s t i c a l l y s ig n i f i c a n t d iffe re n c e ( a t the .05 s ig n ific a n c e le v e l) in long-term average annual b l u f f l i n e recession rates along the Wisconsin study area between b lu f fs encompassing dune sand and b lu f f s composed o f non-sand dune sediments ............................ 69 9. Results o f a Student's jt t e s t in d ic a tin g th a t there is s t a t i s t i c a l l y no s ig n if ic a n t d iffe re n c e (a t the .05 s ig n ific a n c e le v e l) in the long-term average annual recession rates between the Wisconsin and Michigan b lu f f s encompassing dune sand ( i . e . , a l l sand dune s ite s and dune sand underlain by w a te r- la id sand b l u f f s i t e s ) ............................................. 70 10. A e ria l photos u t i l i z e d f o r the Shoreham, Michigan, and northern Kenosha County, Wisconsin, case study i n v e s t i g a t i o n s ......................................................................................93 11. B l u f f recession rates a t the Shoreham, Berrien County, Michigan, case study s it e s , 1967 to 1977, 1 938 to 1967, and 1938 to 1977 ............................................................. 100 12. Average annual b l u f f c re s t recession rates f o r various time periods a t s i t e Ml, South Line / Section 4 / T5S,R19W, Shoreham, Berrien County, M ic h ig a n ............................................................................................................ 104 13. Selected b l u f f p r o f il e s in the northern Kenosha County case study area................................................................................................ 114 14. B l u f f recession rates a t the northern Kenosha County, Wisconsin case study s i t e s , 1969 to 1975, 1941 to 1969, and 1941 to 1975 ......................................................................................... 118 A1. Shorezone term inology used in t h is s t u d y .............................................143 B1. Selected c h a r a c te r is tic s o f the Wisconsin study s i t e s .................... 148 B2. Selected c h a r a c te r is tic s o f the Michigan study s ite s .................. 158 Cl. Long-term b l u f f l in e changes and lo c a tio n s o f the Wisconsin study s i t e s ....................................................................................169 C2. Long-term b l u f f l in e changes and lo c a tio n s o f the Michigan study s ite s ................................................................................. 179 x LIST OF FIGURES Study areas and s ite lo c a t io n s ........................................................ 4 Shorezone features re fe rre d to in t h is s tu d y ............................ 25 Long-term average annual water le v e ls o f Lake Michigan. . . 32 S ite lo c a tio n s and t h e i r long-term average annual b l u f f 1ine changes................................................................................. 40 The shorezone a t s it e W3, South Line / Section 17 / T1N,R23E, Kenosha County, Wisconsin ............................................ 48 B l u f f recession r e s u ltin g from wave erosion and mass-wasting............................................................................................. 50 The shorezone a t s it e M4, North Line / Section 6 / T4S,R18W, Berrien County, Michigan................................................ 52 The shorezone a t s ite s M42 (extension o f the road on the r i g h t ) , South Line / Section 15 / T21N.R17W, and M43 ( l e f t ro ad ), C e nterline / Section 15 / T21N,R17W, Manistee County, Michigan ................................................................. 53 The shorezone a t s i t e W27, South Line / Section 25 / T12N,R22E, Ozaukee County, Wisconsin.................... ... .................... 55 The shorezone a t s it e W35, South Line / Section 14 / T14N,R23E, Sheboygan County, Wisconsin........................................ 56 The shorezone a t s it e W47, South Line / Section 24 / T18N,R23E, Manitowoc County, Wisconsin........................................ 58 The b l u f f a t s i t e W60, South Line / Section 16 / T24N,R25E, Kewaunee County, Wisconsin ........................................ 59 The lake te rra ce forming the shoreland along section 34 o f Ahnapee Township (T25N) and sections 3 and 10 o f Pierce Township (T24N), Kewaunee County, Wisconsin . . . 60 The shorezone in 1968 and 1977 a t s it e M51, South Line / Section 13 / T28N,R15W, Leelanau County, Michigan ................ 62 xi Page Figure 15. 16. 17. 18. 19. Sand dune erosion and a ccretio n between 1968 and 1977 a t s i t e M31, South Line / Section 33 / T13N,R18W, Muskegon-Oceana county l i n e , Michigan ............................................ 72 V a ria tio n in beach widths a t the South Line / Section 15 / T12N,R18W, Muskegon County, Michigan, 1973-1977 ..................................................................................................... 84 Loss o f homes due to accelerated b l u f f recession, 1969 to 1978................................................................................................. 95 A p r i l , 1977, a e ria l photograph o f the Shoreham, Berrien County, Michigan, case study area showing the 15 s it e lo c a tio n s , the June 5, 1938, and A p r il 27, 1977, b l u f f l i n e s , and the predicted b l u f f c re s t p o s itio n in 2077................................................................. 99 House being l o s t due to accelerated b l u f f recession between two shorezone s tru c tu r e s , 1975 to 1978............................. 105 20. S ite SI4 (Table 13 and Figure 18) in the North % / Section 9 / T5S,R19W, Shoreham, Berrien County, Michigan.............................................................................................................. 107 21. B l u f f recession and loss o f a house fo llo w in g a breach in the seawall by storm waves, 1973 to 1978 ................................. 108 22. S ite o f a feeder beach, 1977-78 ............................................................... I l l 23. B l u f f recession in the North % / Section 5 / T2N,R23E, Kenosha County, Wisconsin, 1959 to 1976 ......................................... 113 May, 1975, a e ria l photograph o f the northern Kenosha County, Wisconsin, case study area showing the 22 s it e lo c a tio n s , the October 28, 1941, and May 27, 1975, b l u f f lin e s , and the predicted b l u f f c re s t p o s itio n in 2075................................................................................................................. 116 S ite K6 in the South % / Section 5 / T2N,R23E, Kenosha County, Wisconsin ..................................................................... 122 24. 25. 26. Generally protected against storm waves by a broad beach te rr a c e , the b l u f f in t h is p o rtio n o f Section 8 / T2N,R23W, Kenosha County, Wisconsin has undergone no c re s t recession since a t le a s t 1 9 4 1 ..................................................... 123 27. A e ria l photos taken in 1937, 1950, and 1963 showing the r e l a t i v e l y broad beach te rra c e f r o n tin g the b l u f f segment encompassing s ite s K14-K17......................................................... 124 x ii Page Figure 28. 29. G oldthw ait's (1907) sketch map o f a cuspate foreland located about one m ile south o f the northern Kenosha County, Wisconsin case study area, showing the supposed eddies in the shorezonec u rre n t ......................................... 125 B l u f f p ro te c tio n measures in the North h / Section 8 / T2N,R23E, Kenosha County, Wisconsin. . . . .................................... 127 30. Broken concrete slabs armoring the b l u f f slope in the South ^ / Section 8 / T2N,R23E, Kenosha County, Wisconsin..........................................................................................................128 31. Unwise co n stru ctio n along the Kenosha County, Wisconsin shorezone.................................................................................... 137 xi i i Chapter 1 OBJECTIVES, METHODOLOGY AND LITERATURE REVIEW In tro d u c tio n B lu ffs o f unconsolidated sediments along much o f the Lake Michigan shorezone^ have experienced s ig n i f ic a n t recession; f o r some segments o f the lakeshore b l u f f c re s t r e tr e a t may be in the magnitude o o f several miles in the l a s t 4,000 years (Andrews, 1870; Maxwell, 1919; N iendorf, e t a l . , 1967) and, in places, losses o f over 1,000 fe e t in the l a s t 140 years are su b s ta n tia te d . Erosion o f these b lu f f s is o f increasing concern due to i n t e n s i f ie d occupation and gen e ra lly high land values along the lakeshore. Storm systems moving over the water, e s p e c ia lly in f a l l and s p rin g , may generate waves th a t erode the shoreland. Beaches, which tend to be r e l a t i v e l y wide during low water ele va tio n s and thus provide p ro te c tio n f o r the shorezone b l u f f s , may decrease in width or even disappear due to inundation w ith r is in g lake le v e ls . Since 1875 the le ve l o f Lake Michigan has varied 6.5 fe e t in e le v a tio n and there have been nine p e riod s, ranging from one to 20 years, when average annual water le v e ls have been above the mean; during these times storm waves more r e a d ily reach and erode the base and ^Lakeshore term inology used in t h is study is defined in Appendix A and shorezone features are i l l u s t r a t e d in Figure 2 o f Chapter 2. 2 M e tric equivalents are shown in parentheses only f o r precise b l u f f recession measurements. 1 subsequently the c re s t o f the b l u f f . 3 Accelerated erosion may continue fo llo w in g lake le v e l subsidence u n t il denuded slopes s t a b i l i z e and become revegetated. O bjecti ves This study has three basic o b je c tiv e s : (1) To determine long-term b l u f f c re s t recession a t a number o f s ite s along the Michigan and Wisconsin lakeshores and to compare these fin d in g s w ith selected c h a r a c te r is tic s o f the shorezone. (2) To t e s t the hypothesis th a t w it h in the segments examined b l u f f c r e s t recession is greater on the eastern side o f the la ke . Most shorezone erosion is thought to be a t tr ib u t e d to wave erosion during in te n s iv e f a l l and s p rin g c y c lo n ic storms (Seibel , 1972; Davis, S e ib e l, and Fox, 1973). Because a major component o f the storms involves an e a s te rly movement i t may be th a t the b lu f f s on the east side o f the lake recede a t a f a s te r ra te since w e s te rly winds tend to have higher v e lo c it ie s and may be o f longer dura tio n than those from the east. Lim ited studies ( S a v il le , 1953; Davis and Fox, 1974) in d ic a te th a t a greater amount o f deep water storm wave energy is tra n sm itte d toward the Michigan shore than toward the Wisconsin la ke sid e . (3) To in v e s tig a te two areas in d e ta il and to p r e d ic t fu tu re b l u f f c re s t p o s itio n s and suggest possible consequences r e s u ltin g from r e tr e a t in g b lu f f s a t these lo c a tio n s . 3 Although waves are the major agents o f e ro sio n , other fa c to rs may play im portant ro le s in b l u f f recession. 3 Study Areas This in v e s tig a tio n focuses on selected s ite s along two segments o f the Lake Michigan shorezone: these extend from (1) the I l l i n o i s - 1,'i scons in sta te l in e northward to the Sturgeon Bay Canal in Door County, Wisconsin, and (2) from the Indiana-Michigan border northward to the northern t i p o f the Leelanau Peninsula in Leelanau County, Michigan (Figure 1 ). These areas c o n sist o f unconsolidated Pleistocene and Recent sediments and represent about 74% o f the t o t a l Lake Michigan shoreland designated as being subject to e rosion. Approximately 88% 4 o f those lakeshore segments i d e n t if ie d as c r i t i c a l erosion areas by the Corps o f Engineers (U.S. Army Corps o f Engineers, 1971a) are w ith in the study areas. Basic C r it e r ia Study s ite s are from selected lo c a tio n s where U.S. Public Land Survey section lin e s in te r s e c t the Lake Michigan b l u f f . I t is a t these places where long-term changes in b l u f f c re s t p o s itio n can be determined by comparing measurements a v a ila b le in the o r ig in a l General Land O ffic e 5 (GLO) survey notes w ith more recent surveys. In a d d itio n , f i e l d measurements taken in 1957 (Powers, 1958) are a v a ila b le f o r many o f these s i t e s ; these provide a basis f o r the determ ination o f sh o rt-te rm changes (1957 to 1976-77) in b l u f f p o s itio n s . 4 C r it ic a l erosion areas are defined as those reaches o f sh o re lin e having e x is t in g high value economic and re c re a tio n a l resources and a h i s t o r i c record o f rapid loss o f land and/or s tr u c tu r a l damage. A ll other sh o re line reaches recording erosion damage are c la s s if ie d as n o n c r itic a l erosion areas (U.S. Army Corps o f Engineers, 1971a, p. 3). 5 The o r ig in a l GLO surveys in the Michigan and Wisconsin study areas were conducted between 1827 and 1852. 4 M56 50 25 miles Leelanau Door W62 Benzie Kewaunee M49 Manistee W52 Manitowoc Maaon Sheboygan M36 W36 Oceana Ozaukee Muskegon W17 Milwaukee { Ottawa Racine y M14 — case study area H | Allegan Kenosha : W1 Van Buren _J Ml case study area Study Area Berrien W7 ©7— w i J Site Locations Site Numbers ■ Case Study Area Figure 1. Study areas and s it e lo c a tio n s . 5 Only s ite s where shorezone b lu f fs e x is t are considered in study. t h is A b l u f f is defined as a lakeward-facing steep bank o r sharp slope composed o f unconsolidated m aterial landward o f the s h o re lin e . B l u f f crests provide r e li a b le standardized lin e s to which measurements can be made. Water lin e s are less acceptable because the surface a lt i t u d e o f Lake Michigan flu c tu a te s to a considerable degree. Measurements o f b l u f f change r e fe r to the landward displacement or lakeward a c cretio n o f the top edge o f the b l u f f s . I t should be recognized, however, th a t changes may take place on the b l u f f slope th a t do not nece ssa rily a f f e c t the p o s itio n o f the c re s t. Except f o r the case study areas, b l u f f top changes were determined on the basis o f f i e l d measurements during the f i e l d seasons o f 1976 and 1977 by u t i l i z i n g standard surveying techniques.^ D escription and Use o f the General Land O ffic e Surveys In p r a c t i a l l y a l l instances the o r ig in a l GLO surveys o f Michigan and Wisconsin represent the e a r l ie s t q u a n tita tiv e records o f the Lake Michigan b l u f f l i n e p o s itio n . Distances from section and qu a rte r section corners w it h in a m ile o f the lake to the Lake Michigan "meander l i n e " are recorded in the GLO notes. According to Powers (1958, pp. 89-90) "the 'meander l i n e ' was never p re c is e ly defined, but c le a r ly i t was seldom, i f ever, i d e n t i f i e d w ith the water l i n e . In many cases the measurements were obviously made to some p o in t a t or near This is c o n tra ry to most recent studies o f the Lake Michigan shorezone. The extensive shoreland reaches, budget problems, and personnel lim it a t io n s have re su lte d in the increasing use o f a e ria l photogrammetric methods in determining b l u f f losses and gains. 6 the edge o f the b l u f f , where prese n t." 7 For s ite s selected in th is in v e s tig a tio n i t is assumed th a t the meander l i n e represented the lakeward b l u f f c re s t and a l l resurveys were conducted a cc o rd in g ly . 8 Some s ite s where measurements are fe a s ib le were e lim inated from t h is study because o f the questionable r e la tio n s h ip between the meander li n e and the b l u f f c r e s t. I t is possible t h a t b l u f f recession determined f o r some o f the 118 s ite s may be in e r r o r . But i f e rro rs do e x is t they are believed to be very few and the large number o f s ite s w ith appropriate data provide a sound basis fo r a n a ly s is . By resurveying and comparing these section lin e distances w ith the GLO measurements long-term and average annual b l u f f top changes can be ascertained a t places where the section l i n e in te rs e c ts the lakeshore b l u f f . In a few cases, however, c a lc u la te d losses or gains may "be somewhat less [ o r more] than the actual wherever the o r ig in a l meander li n e was in land from the b l u f f edge" (Powers, 1958, p. 90). Surveying Procedures Inform ation was obtained from lo c a l surveyors, r e g is te r s o f deeds and/or road commissioners or engineers concerning recorded witnesses to desired section corner lo c a tio n s and p re v io u s ly conducted ^Breed, Hosmer, and Bone (1970, p. 162) in d ic a te th a t the meander l i n e may be found a t the top o f an escarpment formed by wave erosion. O Previous Lake Michigan shorezone researchers have u s u a lly equated the meander l i n e w ith the c re s t o f the b l u f f where one e x is ts (Chamberlin, 1877; Powers, 1958; S eib e l, 1972; Jannereth, 1975; among o th e rs ). For example, in a l l o f the Corps o f Engineers' erosion control studies conducted w it h in the study areas the o r ig in a l survey distances from the section corners to the meander l i n e , and a l l subsequent resurveys, were i d e n t i f i e d as being from "s e c tio n corner" to " b l u f f c re s t" (U.S. Army Corps o f Engineers, 1946, 1953, 1955, 1958, 1975). 7 l o t o r su b d iv is io n measurements th a t were run along the section lin e s toward the la ke . Commonly these surveys provided a p reviou sly measured distance from the sectio n corner to a survey marker on the l i n e ; consequently, only the remaining distance to the b l u f f top had to be measured. In a few cases where records were la c k in g and f i e l d monuments could not be found i t was possible to determine section corner lo c a tio n s by fence and road patterns f a i r l y a ccurately (w ith in three to f iv e f e e t ) . A ll measurements to the b l u f f follow ed as c lo s e ly as possible to the tru e bearing o f the section l i n e . I f two points known to be on the section l i n e were found, the li n e between them established the bearing. In oth e r cases i t was assumed t h a t the section l in e coincided w ith the center l i n e o f a road or a fence row. At the few lo c a tio n s where the survey lin e s are not apparent, measurements were made along an east-west tre n d . Distances along the section l i n e were established by using a 100-foot e n g ineer's steel tape and/or by s ta d ia method u t i l i z i n g a t r a n s i t and P h ilad e lp h ia and/or sta d ia rod ( f o r short and long distances, r e s p e c tiv e ly ) ; standard surveying procedures were followed (Davis, Foote, and K e lle y , 1966; B rin k e r, 1969; Breed, Hosmer, and Bone, 1970). Some distances were obtained from p re v io u s ly performed surveys by re g is te re d land surveyors ( R .L .S .). The probable e r r o r in measurement ranged from one fo o t in 5,000 fe e t f o r the R.L.S. distances to an e r r o r o f approximately 0.25% or less fo r the s ta d ia method. g Fence lin e s and roads commonly coin cid e w ith boundaries o f the land survey system. 8 A ll measurements were to the c re s t o f the lakeshore b l u f f . In places where pedestrian or v e h ic u la r t r a f f i c had notched sags in the b l u f f ' s upper boundary so th a t an abrupt departure in slope was not e vid e n t, the resurvey was c a rrie d to an imaginary l in e connecting the b l u f f edge on e it h e r side o f the s it e l i n e . At lo ca tio n s where the b l u f f c re s t was rounded a somewhat a r b i t r a r y edge p o s itio n was esta b lis h e d , r e s u ltin g in an estimated e r ro r o f less than three fe e t. S ite Selection A ll section lin e s in te r s e c tin g Lake Michigan w it h in the study areas were in v e s tig a te d . Of those where b lu f f s e x is t 118 were resurveyed, 56 in Michigan and 62 in Wisconsin (Figure 1 ) . ^ For each o f these long-term changes in b l u f f p o s itio n were computed on the basis o f comparison w ith the GLO surveys. S ite Observations The fo llo w in g co n d itio n s were examined at each s i t e : (1) B l u f f Composition. Sediments comprising the b l u f f p r o f i l e were examined, hand te x tu re d , and categorized according to the U.S.D.A. At a l l o th e r lo ca tio n s problems were encountered and the p o te n tia l s ite s had to be e lim in a te d . These problems were re la te d to one or more o f the fo llo w in g : (a) the lack o f confidence in the o r ig in a l GLO survey measure­ ment; (b) the i n a b i l i t y to re lo ca te appropriate survey corners o r to re tra ce the o r ig in a l survey l i n e to the lake b l u f f ; (c) a lt e r a t io n o f the lakeshore b l u f f edge by pedestrian and/or v e h ic u la r t r a f f i c ; (d) the existence o f s tru c tu r e s , d ra in s , and/or a r t i f i c i a l f i l l in the shorezone; (e) the nature o f the b l u f f composition and p r o f i l e (e s p e c ia lly in the sand dune areas); and ( f ) the lack o f a d e fin a b le b l u f f . 9 s o il te x tu ra l t r ia n g le classes (S o il Survey S t a f f , 1951). M o difiers o f class names were used to in d ic a te the presence o f p a r tic le s greater than 2 mm. The genesis o f the material was in d ica te d i f such a determ ination could be made. I f overburden covered a ll or p a rt o f the b l u f f face the nature o f the sediment(s) was fre q u e n tly determined by in sp e ctin g exposures adjacent to the s i t e l i n e . (2) B l u f f Height. B l u f f height was usu a lly e stablished by hand le ve l but o c c a s io n a lly i t was necessary to u t i l i z e topographic maps. (3) Shoreline O rie n ta tio n . The trend o f the sh o re lin e was determined from U.S.G.S. topographic maps by measuring the bearing o f a li n e tangent to the shore from a p o in t one-quarter m ile southward to one-quarter m ile northward o f the section l i n e . (4) Ground Water and A r t i f i c i a l Drainage. Where possible the presence o f a r t i f i c i a l drains and evidence o f ground water seeps w ith in the b l u f f slope were noted in the v i c i n i t y o f the section l i n e s i t e ; i t is l i k e l y , however, th a t many were overlooked because o f the i n t e r ­ m itte n t nature o f the seeps or b u ria l by mass-wasted m a te ria l. (5) Beach Width. Beach width was determined by pacing. I t is apparent, though, th a t the character and in flu e n ce o f the beach may vary w ith changes in such va ria bles as lake le v e l , shorezone s tru c tu r e s , wave o r ie n t a t io n , and weather c o n d itio n s. (6) Shorezone S tru ctu re s . A ll s tru c tu re s in the v i c i n i t y o f the section l i n e were noted and t h e i r apparent in flu e n ce on the shorezone recorded. (7) B lu ff S ta b ility . An appraisal o f b l u f f s t a b i l i t y was made a t each s i t e ; o f p a r t ic u la r in t e r e s t was evidence o f mass-movement on the slope. Furthermore, co n d itio n s and processes o ccu rrin g between and a t the b l u f f base and the c re s t were noted. 10 (8) Photo Record. Photographs were taken o f both beach and b l u f f top c o n d itio n a t the section l i n e s i t e and v i c i n i t y . These were help fu l during data an a lysis and may prove useful f o r fu tu re stu d ie s . L ite r a tu r e Review Erosional problems along the shore o f Lake Michigan in Wisconsin and Michigan were recognized as e a rly as the middle 1800's by Lapham (1847). Later in the century W hittle se y (1867), Andrews (1870), Chamberlin (1877), Wool rid g e (1884), and L e ve re tt (1899) also d ire c te d a tte n tio n to such c o n d itio n s . Numerous subsequent references show th a t erosion has continued to be a serious concern to many l o c a l i t i e s , e s p e c ia lly during periods o f high water e le v a tio n s (Maxwell, 1919; B a ll, 1920, 1938; Wojta, 1945; B ra te r, 1950a; Granger, 1957; Pincus, 1962; S e ib e l, 1972; Davis, S e ib e l, and Fox, 1973; Consoer, Townsend, and Associates, 1973; Hadley, 1976; Mickelson, e t a l . , 1977; among many). The l i t e r a t u r e has focused on various aspects o f the problem. For example, some authors have published data on rates o f lakeshore b l u f f recession, others have re la te d shorezone erosion to s p e c if ic processes and/or v a ria b le s , whereas s t i l l others have d e a lt w ith p ro te c tio n and management o f the shorezone or were concerned only w ith dissem inating general info rm a tio n about lakeshore c o n d itio n s . Shoreland erosion losses have been ascertained by numerous in v e s tig a to rs . Some have determined rates o f r e t r e a t by actual f i e l d survey methods (Andrews, 1870; Chamberlin, 1877; L e v e re tt, 1899; Ball and Powers, 1930; Powers, 1958; Davis, 1971, 1972, 1973, 1976; Davis and F in gleto n , 1972, 1973; F in g le to n , 1973; Davis, F in g le to n , and P r i t c h e t t , 1975; Buckler, 1973; Buckler and W inters, 1975; and Maresca, 1975). Commonly these recession rates were ca lcu la te d f o r 11 lo c a tio n s c o in c id in g w ith section li n e s ; distances recorded in the o r ig in a l land survey notes along these lin e s provide a base to which more recent measurements can be compared. p r o je c t by Powers (1958). Of special in t e r e s t is the He resurveyed 134 section l i n e lo c a tio n s and c a lc u la te d average annual losses or gains fo r each s i t e ; 106 o f these are w ith in the present study areas. Other researchers have r e lie d on measurements from a e ria l photography to asce rta in rates o f shoreland r e tr e a t (U.S. Army Corps o f Engineers, 1946, 1953, 1957, 1958, 1975; Farrand, 1970; S eib e l, 1972; B rater and S e ib e l, 1973; Frankovic, 1975; and the present Michigan Department o f Natural Resources sho re line erosion program). K e il lo r and DeGroot (1978) ascertained b l u f f recession rates along the Racine County, Wisconsin, shore by comparing two sets o f 1 :2,400-scale topographic maps compiled from s p e c ia lly flown a e ria l photography. S e ib e l, Armstrong, and Alexander (1976) have compiled in to one p u b lic a tio n a l l a v a ila b le recession ra te data from various agencies, in d iv id u a ls , and previous re p o rts . For each sho re line reach f o r which data are a v a ila b le they have estimated a weighted average annual, maximum annual, and minimum annual recession r a te . Monteith and Sonzogni (1976; see also M onteith, 1977, and Sonzogni, M onteith, and S e ib e l, 1978) u t i l i z e d much o f the raw data o f the aforementioned re po rt to estimate the volume o f m aterial eroded and to determine whether shore erosion is l i k e l y to be a s ig n i f i c a n t p o llu t a n t source to the Great Lakes. Chamberlin (1877), Powers (1958), Seibel (1972), Buckler (1973), Buckler and Winters (1975), and S e ib e l, Armstrong, and Alexander (1976) determined th a t b l u f f erosion rates are not uniform a t selected sh o re line s ite s nor can they be a n tic ip a te d to be s im ila r a t s ite s w ith s im ila r 12 c h a r a c te r is tic s during two o r more d i s t i n c t time periods. Davis (1971; 1972; 1973; 1976), Davis and Fingleton (1972; 1973), Fingleton (1973), and Davis, F in gleto n , and P r it c h e t t (1975) found a lack o f c o rre la tio n between beach p r o f i l e changes a t adjacent s ite s even though observed c h a ra c te r is tic s were s im ila r . W hittlesey (1867) observed th a t in southwestern Michigan promontories were eroding fa s te r than bays or curves in the s h o re lin e , thus g iv in g the lake a more re g u la r o u t l in e . ^ 1 Goldthwait (1907), Alden (1918), and Ball (1920; 1938) indicated th a t b l u f f recession has been ra p id enough along parts o f the present lake to truncate many ancestral Lake Michigan shoreline features. Lapham (1847), Goldthwait (1908), Alden (1918), Ball (1920), and Thwaites (1931) discussed the process o f " in t e r c is io n " whereby b l u f f r e t r e a t along the Wisconsin shore had in te rce p te d bends in streams g e n e ra lly p a r a lle l in g the lake so th a t t h e i r va lle ys presented three openings to Lake Michigan instead o f the normal one. As e a rly as 1867 W hittlesey re a liz e d the importance o f lake le v e l e le v a tio n to s h o re lin e e rosion , which tends to be accelerated during high le v e ls and diminished during lower water periods. Goldthwait (1907), Ball and Powers (1930), and Kingery (1944), among o th e rs , published recession rates f o r a number o f s ite s to emphasize t h is p o in t. Although Seibel (1972) " q u a n t it a t iv e ly established" a p o s itiv e r e la tio n s h ip between mean annual lake le ve ls and the average ra te o f b l u f f lin e r e t r e a t , Davis, S e ib e l, and Fox (1973, p. 406) stressed th a t "high lake le v e ls play a passive ro le in th a t they 'a llo w ' erosion to take place a t a ra p id r a te ; they do not 'cause' i t to do so ." ^ I n t e r e s t i n g l y , Carter (1975, p. 163) re c e n tly pointed out t h a t the present Lake E rie s h o re lin e is g e ttin g more ir r e g u la r , b a s ic a lly due to d is ru p tio n o f the longshore d r i f t o f sand. 13 Following in te n s iv e study o f successive high water cycles along p a rt o f the I l l i n o i s high b l u f f s h o re lin e , Berg and C ollinson (1976; Collinson and Berg, 1976) suggested several g e n e ra liza tio n s concerning b l u f f recession along Lake Michigan: (1) S ig n if ic a n t b l u f f recession begins once the lake has exceeded a le ve l o f 579 f e e t , e s p e c ia lly i f p ro te c tiv e stru ctu re s are la ckin g and l i t t o r a l d r i f t is minimal, and even i f well-developed beaches e x is t . (2) F a llin g lake le v e ls do not n e ce ssa rily s ig n if y immediate decrease in b l u f f recession because time is required fo r revegetation o f the denuded slopes. (3) Maximum erosion may be delayed during r is in g lake le v e ls u n t il p re v io u sly b u i l t beaches are degraded. Davis (1976), however, suggests th a t the c r i t i c a l le ve l along the eastern shore o f the lake is 580 f e e t ; and above th is e le va tio n erosion occurs everywhere. Recently three Lake Michigan studies tested v a ria tio n s o f the 1p "Brunn e f f e c t . " Larsen (1973, p. 67) theorized th a t "given s im ila r b l u f f height and composition, the r e tr e a t o f the base o f the b l u f f is in d ir e c t prop o rtio n to the water le v e ls to which i t is exposed." His fin d in g s , however, in d ic a te d a one to te n fo ld v a r ia tio n in t h is a n tic ip a te d r e la tio n s h ip . He p a r t i a l l y a t t r ib u t e d t h is c o n tra d ic tio n to e re c tio n o f man-made s tru c tu re s along the shore. Tanner (1975) reasoned th a t "a s ig n if ic a n t r is e in lake le v e l should be accompanied and followed by an im portant increase in beach e ro s io n ; much or most o f the sand eroded should be c a rrie d o ffsh o re ra th e r than in the l i t t o r a l d r i f t system." 12 He reports th a t t h is " th e o r e tic a l p ro je c tio n is Brunn (1962; Schwartz, 1976) believes th a t as sea le v e l ris e s the sediments eroded from the upper beach should be deposited in equal volume in the nearshore zone; the r e s u ltin g r is e in the nearshore bottom should correspond d i r e c t l y w ith the r is e in the water le v e l. 14 confirmed" along the Berrien County, Michigan, shore. DuBois (1976) reported th a t the Brunn e f f e c t is ap p lica b le in the zone o f the f i r s t longshore bar system in Lake Michigan a t Terry Andrae State Park, Sheboygan County, Wisconsin. Early observers, such as Lapham (1847) and Woolridge (1884), recognized th a t s ig n i f i c a n t shorezone erosion occurred during storm co n d itio n s . S e ib e l's (1972, p. 138) " in v e s tig a tio n produced no c o r re la tio n between the average number o f cyclones and average rate o f erosion-average lake l e v e l , " suggesting " t h a t i t is not the t o t a l number o f storms but ra th e r the la rg e r is o la te d storms th a t have a greater bearing on the ra te o f e ro s io n ." The recent beach and nearshore environment studies by Fox and Davis (1970a, 1970b, 1971a, 1971b, 1 973a, 1973b; Davis and Fox, 1971, 1972a, 1972b; Davis, 1976) along the eastern shore o f Lake Michigan also in d ic a te th a t i t is during intense storms o f short d u ration when the most severe erosion is l i k e l y to take place, although erosion rates along the shore may vary considerably during a s in g le storm. They believe th a t lo ca l v a ria tio n s in erosion are la r g e ly due to "s u b tle d iffe re n ce s in nearshore topography" (Davis, S e ib e l, and Fox, 1973, p. 408). The amount o f wave energy a v a ila b le a t a given lo c a tio n depends on the p o s itio n and depth o f longshore sand bars in the nearshore zone. More re c e n tly K e i l l o r and DeGroot (1978) characterized the storm wave energy eroding the Racine County, Wisconsin, sh o re line between 1968-1976. They b elieve th a t ir r e g u la r o ffs h o re bottom fe a tu re s , and e s p e c ia lly re e f s tru c tu r e s , in flu e n c e the d ir e c tio n o f incoming waves and cause a complex p a tte rn o f wave energy d iff u s io n and concentration along the shore. 15 Maresca (1975) measured b l u f f lin e recession and beach and nearshore changes a t t r ib u t a b le to the passage o f nine in d iv id u a l storms along a th re e -k ilo m e te r sandy s tre tc h in southwestern Michigan. He observed a rhythmic p a tte rn w ith in the sh o re line segment and recognized three d i s t i n c t i v e length scales under which the s p a tia l d is t r ib u t io n o f b l u f f li n e recession operated. The la rg e s t length scale was a t t r ib u t e d to the convergence and divergence o f wave energy by r e f r a c t io n . The middle length scale was a t tr ib u t e d to the unequal d is t r ib u t io n o f breaker heights in the nearshore zone and the sm allest scale was the r e s u lt o f the unequal f a i l u r e o f the b lu ff. C o n flic tin g opinions have been expressed as to the re la tio n s h ip s between b l u f f l it h o l o g y and recession ra te s . Alden (1918, p. 338) reported th a t "where much sand and s o ft c la y o c c u r .. .erosion is easy and the b l u f f recedes r a p i d l y . " Chieruzzi and Baker (1959, p. 114) noted th a t "the material present in the b l u f f w i l l c o n t r o l, to a great e x te n t, the ra te o f recession." Likewise, Wilkinson and Gray (1978) suggest th a t la t e r a l v a ria tio n s in lit h o lo g y o f the d r i f t are d i r e c t l y c o r r e la tiv e w ith s p a tia l v a r ia tio n s in recession rates along a 1 0 -kilo m e te r s tre tc h o f Lake Michigan near Glenn, Michigan. Davis, S e ib e l, and Fox (1973, p. 407), however, found t h a t , a t selected s ite s along the eastern Lake Michigan shore, recession "ra te s show no p a tte rn th a t may be c o rre la te d w ith coastal com position." A s im ila r conclusion was reached by Buckler (1973; Buckler and W inters, 1975), a t le a s t on a long-term (approxim ately 140 years) basis. Results o f a three-year beach p r o f i l e study also along the eastern reach o f Lake Michigan in d ic a te th a t " b lu f f s composed o f t i l l eroded a t on ly o n e -h a lf the ra te o f predominantly sandy b lu f f s or dunes" (David, F in g le to n , and P r it c h e t t , 1975, p. 57). Seibel (1972), nonetheless, reported th a t 16 cla y t i l l b lu f f s re tre a te d a t a higher ra te than sand b lu f f s during a downward trend in Lake Michigan water le v e ls . because the slopes o f the t i l l He believes t h is resulted b lu f f s may stand v e r t i c a l l y fo llo w in g wave a tta c k , "but e v e n tu a lly , [even i f lake le v e ls drop and there is no d ir e c t wave im pact] surface r u n o f f , seepage, and fre e z in g and thawing, combined w ith the load o f the m aterial above, may cause the b l u f f to d is in te g ra te " ( p . 86). This may explain a t le a s t some o f the apparent c o n tra d ic tio n between Davis, e t a l . and S eibel. The s t r a t i graphic sequence o f m aterial w ith in the b l u f f may have a considerable in flu e n c e on the c h a r a c te r is tic s o f recession and erosion (Pincus, 1962; Edil and V a lle jo , 1977; M ickelson, e t a l . , 1977), e s p e c ia lly when ground water p e rc o la tio n is present. "Slope f a ilu r e caused p r im a r ily by ground water seepage and [p o re w a te r] pressure is a common occurrence in coastal b lu f f s along the Great Lakes" (Gray, 1975, p. 12). The problem is o fte n compounded where the arrangement o f b l u f f m aterial includes a lt e r n a t in g layers o f pervious and r e l a t i v e l y impervious unconsolidated deposits. Lapham (1847), Whitney (1936), Murphy and Keim (1968), Hadley (1974; 1976), and Lee (1975) cre dite d ground water p e rc o la tio n as a prime cause f o r b l u f f recession along several Wisconsin lakeshore segments. Surface r u n o ff can also c o n trib u te s i g n i f i c a n t l y to b l u f f slope r e tr e a t and erosion (Chieruzzi and Baker, 1958; Pincus, 1962). Ball (1920) disclosed t h a t drainage from t i l e d f i e ld s f a c i l i t a t e d slumping o f a Wisconsin b l u f f whereas Buckler (1973) reported th a t cha n n e liza tio n o f r u n o ff i n i t i a t e d severe g u lly in g in t o the b l u f f slope. 17 Recently a tte n tio n has focused on the importance o f vegetation on the shorezone b l u f f slopes (Hall and Ludwig, 1976; Acres Consulting Services, 1976; Dai, H i l l , and Smith, 1977; Great Lakes Basin Commission and U.S.D.A. Soil Conservation Service, 1977; and I l l i n o i s Coastal Zone Management Program, 1978). I t is recognized th a t vegetation is not an e f f e c t iv e measure against wave forces (Haras, 1977) but i t s influence on t e r r e s t r i a l slope processes can be q u ite s ig n i f i c a n t . Vegetation helps to co n tro l t e r r e s t r i a l slope erosion and mass-wasting by ro o t reinforcement o f s o i l , by r e s t r a in t and " f i l t e r i n g " o f s o il p a r t i c l e s , by r e s t r a in t o f s o il masses on slopes by " s o il- a r c h in g " e f f e c t s , by in te rc e p tio n o f p r e c i p i t a t io n , by re ta rd a tio n o f r u n o ff and maintenance o f i n f i l t r a t i o n capacity and by deple tio n o f s o ilw a te r (Gray, 1977, p. 5). Furthermore, i t is vegetation th a t la r g e ly allows lakeshore dunes to form and be maintained; i t traps and holds sand blown up from the beach, e s p e c ia lly during low water periods. Foredunes b u i l t up during these times may p ro te c t higher in la n d b lu f f s from wave erosion when the lake again ris e s . The U.S. Army Coastal Engineering Research Center (Knutson, 1977) has re c e n tly begun dune-building experiments using American beachgrass and p r a i r ie sand reed along Lake Michigan at Ludington State Park, Michigan. Zumberge and Wilson (1953), O'Hara and Ayers (1972), Davis (1973), and Marsh (1977) have discussed another n atural p ro te c tiv e b a r r ie r . They in d ic a te th a t erosion could be much more severe i f i t were not f o r the formation along the sh o re line o f ic e fo o ts and ic e ridges which s h ie ld the beach and b l u f f from frequent and p o t e n t i a l ly damaging storm waves each w in te r . Shorezone b l u f f geometry is dynamic; i t changes over time as a consequence o f toe erosion and b l u f f face degradation (E d il and 18 V a lle jo , 1977; V a lle jo , 1977). In order to form engineering and management s o lu tio n s to problems created by r e tr e a tin g b lu f f s the mechanics o f slope e v o lu tio n , the mode o f slope f a i l u r e , and the inherent s t a b i l i t y or i n s t a b i l i t y o f the slope have been studied (Mickelson, e t a l . , 1977; Edil and V a lle jo , 1977; V a lle jo , 1977). Goldthwait (1907) recognized th a t the t i l l b lu f f s along the southern part o f the sho re line in Kewaunee, Wisconsin, had been ra p id ly r e tr e a tin g u n t il the town's long piers were con stru cte d ; subsequently a beach formed a t the base o f the b l u f f due to l i t t o r a l d r i f t accumulation caused by entrapment by the p ie rs . I t is believed by many, however, th a t s im ila r and s o -ca lle d p r o te c tiv e shorezone s tru c tu re s may a c tu a lly increase erosion rates along some lakeshore segments because they tra p l i t t o r a l d r i f t and thus l i m i t sand movement and do w n d rift beach formation ( B a ll, 1938). McGee (League o f Women Voters, 1974) and Larsen (1972) have suggested th a t a large percentage o f the present a c c e le ra tio n in shoreland recession along Lake Michigan is d i r e c t l y re la te d to an increase in the number o f s h o re line s tru c tu re s . Part o f the 1968 Federal River and Harbor Act mandated th a t the U.S. Army Corps o f Engineers " in v e s tig a te , study, and co n s tru c t p ro je cts f o r the prevention or m itig a tio n o f shore damages a t t r ib u t a b le to Federal navigation works" (Great Lakes Basin Commission, 1975, p. 54; f o r a d e s c rip tio n o f the various p ro je c ts see U.S. Army Corps o f Engineers, 1977, pp. 64-69). Subsequent studies have in d ic a te d th a t f o r 27 areas o f the Great Lakes sho re line Federal navigation works are w h o lly or p a r t i a l l y responsible f o r shorezone erosion in a t le a s t 17 cases (Omohundro, 1973). For example, the j e t t i e s a t South Haven, Michigan, were determined to cause 81% o f the t o t a l erosion in the 19 nearby shore damage area (U.S. Army Corps o f Engineers, 1974) whereas only 30% o f the t o t a l erosion a t St. Joseph, Michigan, was thought due to the harbor s tru c tu re s (U.S. Army Corps o f Engineers, 1973b; also see Linney, 1976). A study by Gove Engineers (1970) had e a r l i e r concluded th a t the St. Joseph j e t t i e s created conditions under which shoreland erosion was accelerated. Herbert (1974), through a model analysis o f the St. Joseph shorezone, examined the combined environm ental, engineering, and legal approach in p ro vid in g long-term s o lu tio n s to erosion problems along developed shores. Although la r g e ly in c o n c lu s iv e , Frankovic (1975) attempted in a M.S. th e sis to co n stru c t a model to d u p lic a te erosional events along a p o rtio n o f the Milwaukee County, Wisconsin, shoreline and to t e s t the e ffe c tiv e n e s s o f various shore p ro te c tio n s tru c tu re s . Numerous governmental and o th e r p u b lic a tio n s d ire c te d at inform ing the p u b lic about shorezone erosion conditions and processes and/or p ro vid in g te ch n ica l assistance r e la t in g to erosion p ro te ctio n devices and shorezone management a lte rn a tiv e s along Lake Michigan and the Great Lakes are a v a ila b le . 12 B ib lio g ra p h ie s have been published d e a lin g , e n t i r e l y o r in p a r t, w ith sho re line recession and conditions along Lake Michigan ( B r a te r , 1950b; M it c h e ll, 1968; Water Resources S c i e n t i f i c Inform ation Center, 1972; Lasca, 1975; S ta rk , 1975). ^ B r a t e r , B i l l i n g s , and Granger, 1952; B ra te r, 1954, 1 975; Michigan Water Resources Commission, 1970, 1972a, 1972b, 1972c; U.S. Army Corps o f Engineers, 1971a, 1971b, 1971c, 1972, 1973a, 1 973b, 1975c, 1976; Verspoor, 1972; Buddecke, 1973; Michigan Department o f Natural Resources, 1973; Omohundro, 1973; Wisconsin Sea Grant Program, 1973, n . d . ; B ra te r, Armstrong, and M c G ill, 1974, 1975; League o f Women Voters, 1974; Marks and C lin to n , 1974; U y l, 1974; Great Lakes Basin Commission, 1975a, 1975b, 1977; N a p o lii, 1975; Hadley, 1976; H artford and Tanner, 1976; B r a te r, Armstrong, M c G ill, and Hyma, 1977; Hanson, Perry, and Wallace, 1977; Marks, 1977; Mickelson, e t a l . , 1977; Wisconsin Department o f Natural Resources, 1977; Lake Michigan Federation, 1978; Michigan D iv is io n o f Land Resource Programs, 1979a, 1979b. 20 Workshops and conferences have been held concerning shore erosion and planning (Lake Michigan Federation, 1973; Michigan L e g is la tu re , 1974; Great Lakes Basin Commission, 1975b; Great Lakes Basin Commission and U.S.D.A. Soil Conservation Service, 1977; Rukavina, 1978) and several programs have been conducted to study or observe the problems in the f i e l d (Upchurch, 1973; C o llin s o n , Lineback, DuMontelle, and Brown, 1974; Gorder, 1975; Geological Society o f America, 1976; among o th e rs ). C o lle c tiv e ly these numerous references in d ic a te th a t the Lake Michigan shorezone is a dynamic environment th a t is not completely understood. Studies show th a t b lu f f s are receding a t rates th a t are not uniform along the shoreland nor are they n e c e s sa rily s im ila r during two d i f f e r e n t time periods a t a given s i t e . Nearshore topography, storms, ground water seepage, shorezone s tr u c tu r e s , s h o re line o r ie n t a t io n , slope f a i l u r e s , beach c o n d itio n s , and/or b l u f f composition may be im portant fa cto rs a f f e c tin g lakeshore b l u f f recession. Studies contain c o n f lic t in g data and conclusions regarding these r e la tio n s h ip s , however. L i t t l e research has been conducted comparing the conditions between the Michigan and Wisconsin shorezones. I t is possible th a t apparent re la tio n s h ip s e x is t in g along one lakeshore i n t e r a c t in a somewhat d i f f e r e n t fashion elsewhere. Inform ation o f t h is nature may be e s p e c ia lly useful in making estimates o f fu tu re b l u f f c re s t p o sitio n s and decisions regarding shorezone management. 21 J u s t i f i c a t i o n and A p p lic a b ili t y Frequently shorezone occupants have found th a t p ro te c tiv e devices are not e f f e c t iv e in c o n t r o llin g the natural forces th a t erode the s h o re lin e b lu ff s and threaten or destroy t h e i r property ( M it c h e ll, 1974). Some have suggested th a t the le ve l o f Lake Michigan be regulated during periods o f high w a te r, thereby minimizing p o te n tia l shorezone erosion. U n fo rtu n a te ly , t h is proposal leads to c o n f l i c t w ith other lake users; f o r in sta n ce , commercial navigation and power generation concerns b e n e fit from high lake le v e ls . In any case, the In te rn a tio n a l J o in t Commission ( In te r n a tio n a l Great Lakes Levels Board, 1973, p. 4) has concluded a f t e r a 10-year study th a t re g u la tio n o f Lakes Michigan-Huron by co n stru ctio n o f co n tro l works and dredging o f channels a t t h e i r o u t l e t , combined w ith the re g u la tio n o f Lakes Superior and O n ta rio , would not provide b e n e fits commensurate w ith costs and th e re fo re would not be a v ia b le shorezone management a lt e r n a t iv e . Many are now recognizing the need to r e s t r i c t f u r t h e r s tr u c tu r a l encroachment upon the slopes and tops o f those b lu f f s vulnerable to rapid wave erosion. Indeed, the IJC ( In te r n a tio n a l Great Lakes Levels Board, 1973, p. 5) concludes th a t "the most promising measure fo r m inim izing damages to shore property in te r e s ts are s t r i c t land use zoning and s t r u c t u r a l setback requirements." Hadley (1976, p. 30) focuses on a major problem concerning lakeshore zoning, however, when he states th a t there is not a t present time a s u f f i c i e n t body o f fa c tu a l in fo rm a tio n on the geologic, h y d ro lo g ic , and geotechnical o r engineering cond itio n s along the lake to allow ra tio n a l decisions as to the strin ge n cy o f zoning necessary along the various segments o f the coast. 22 In a comprehensive study assessing Great Lakes shoreland management problems the Great Lakes Basin Commission (1975a, p. 12) concluded th a t '‘because o f the dearth o f c r i t e r i a fo r the establishment o f b u ild in g setback and height c o n tro ls , e f f e c t iv e c o n tro ls are generally absent in many s h o re lin e areas o f the Great Lakes." Furthermore, the commission s tro n g ly urged the establishment o f a systematic and comprehensive erosion ra te study th a t would compile h i s t o r i c erosion rates fo r the e n tir e Great Lakes shoreland. Buddecke (1974, p. 5) had p re v io u sly reached a s im ila r opinion at a Great Lakes Recession Workshop where he emphasized: recession ra te in fo rm a tio n is u rg e n tly needed to support Coastal Zone Management a c t i v i t i e s , the Land Drainage Reference Study o f the IJC, the Permit Program o f the Corps o f Engineers, and the Flood Insurance Program administered by the Department o f Housing and Urban Development. A primary goal o f t h is study is to determine and assess h i s t o r i c and recent rates o f b l u f f c re s t recession a t a la rg e number o f s ite s along the erosion prone shorelands o f Wisconsin and Michigan in order to provide r e lia b le data useful in fo rm u la tin g lakeshore management a lte r n a tiv e s and zoning re g u la tio n s . By comparing the east and the west shorezones o f Lake Michigan t h is research also attempts to address such questions as: o th e r side? Is one side o f the lake eroding more r a p id ly than the And are co n ditions s im ila r or is each shorezone characterized by unique problems or processes? Surely most lakeshore b lu f f s w i l l continue to erode in the f u t u r e , although the ra te at which they w i l l recede is open to question. Continued b l u f f recession may have adverse e f f e c t s , p h y s ic a lly , p s y c h o lo g ic a lly , and f i n a n c i a l l y , on shorezone communities. For example, wave erosion o b lit e r a t e d the i n i t i a l 18801s la k e fr o n t se ttlem ent o f 23 Two Creeks, Wisconsin (Wojta, 1945). Road segments in several counties ( f o r in sta n ce , Kenosha and Manitowoc Counties, Wisconsin, Berrien County, Michigan, and P orter County, Indiana) have been destroyed and/or relocated due to appreciable b l u f f recession. Hundred o f houses and re la te d s tru c tu re s have lik e w ise been a ffe c te d . Some shorezone reaches are now r e c r e a tio n a lly unusable, even during low water stages, because hazardous items such as broken concrete s la b s , auto and tru c k bodies, and t i r e s have been dumped on the b l u f f slopes and beaches in an attempt to prevent b l u f f recession. M illio n s o f d o lla rs have been spent on s tru c tu re s to p ro te c t r a ilr o a d and highway rig h ts -o f-w a y in St. Joseph, Michigan, and are being expended in an e f f o r t to m itig a te shorezone erosional damage caused la r g e ly by Federal harbor j e t t i e s a t numerous l o c a l i t i e s along Lake Michigan. In Wisconsin alone, losses in excess o f 30 m il lio n d o lla rs have occurred during the present high lake period due p r im a r ily to wave erosion on the b l u f f (S e ib e l, Armstrong, and Alexander, 1976). With in t e n s if y in g occupation and gen e ra lly r i s i n g land values along the lakeshore fu tu re damages from b l u f f recession could conceivably reach in t o the hundreds o f m illio n s o f d o lla r s . Chapter 2 SHOREZONE CHARACTERISTICS AND CONDITIONS FAVORING SHORELAND EROSION In tro d u c tio n Lake Michigan is s itu a te d w it h in a bedrock lowland mantled in most places by unconsolidated Quaternary sediments. Extending 307 miles in a north-south d ir e c tio n and 118 miles at i t s w idest breadth, its 1,362 miles o f s h o re lin e encompasses a water surface area o f 22,300 square m ile s. The la k e , located in the w e s te rly wind b e l t , experiences p e rio d ic storms producing wave erosion th a t modifies the shorezone topography. Annual and seasonal v a r ia tio n s in p r e c ip ita t io n and evaporation r e s u ltin g from s h i f t s in cy clo n ic storm paths r e s u lt in lake le ve l changes; and these lead to changes in sh o re lin e p o sitio n s and beach w idths. Lakeshore erosion and b l u f f recession appear to be p r im a r ily dependent upon the in te r a c tio n o f onshore storm waves, lake le v e l, shorezone physiography, longshore c u rre n ts , and nearshore hydrographic c o n d itio n s . Shorezone Terminology Shorezone terms used in t h is study are defined in Appendix A and shorezone features are i l l u s t r a t e d in Figure 2. 24 — SHOREZONE NEARSHORE ZONE SHORELAND -M- BEACH o r SHORE INSHORE ZONE 8 AC KS H 0R E BLUFF SLOPE ------- # - •*}*— • M - FORESHORE > ro tn FOREDUNE BLUFF LINE BLUFF BLUFF BASE LITT O R AL ZONE SHORELINE LONGSHORE SANO BARS Figure 2. OFFSHORE ZONE Shorezone features re fe rre d to in t h is study. 26 Shorezone Physiography Shoreland B lu ffs The shoreland b lu f f s considered in t h is study vary from low to high banks o f unconsolidated Quaternary sediments. These la rg e ly c o n s ist o f g la c ia l d r i f t j dune sand, and p o s t-g la c ia l la c u s trin e and shore m aterial 2 and have been described by numerous in v e s tig a to rs . 3 Although the b lu f f s may be composed o f a s in g le sediment exposures commonly reveal two or more s t r a t i graphic components; fo r example, r e l a t i v e l y impermeable zones o f t i l l and/or la c u s trin e clays are often found interbedded w ith permeable layers o f g la c io - f l u v i a l m a te ria l. And b lu f f s in sand dunes may be forming in r e l i c t features associated w ith ancestral p ro g la c ia l lakes o f higher e le va tio n or in modern dunes th a t have formed q u ite re c e n tly along the lake margin. The Wisconsin and Michigan shorelands are s im ila r because both are products o f Pleistocene and Recent processes but s ig n if ic a n t d iffe re n ce s do e x is t . B lu ffs in Wisconsin tend to be lower and, as a whole, are composed o f a la r g e r percentage o f c la y - r ic h m aterial (S e ib e l, Armstrong, and Alexander, 1976; Krumbein, 1950). Sand dunes D r i f t is defined as "any rock m a te r ia l, such as boulders, t i l l , g ra v e l, sand, or c la y , transported by a g la c ie r and deposited by or from the ice or by or in water derived from the m elting o f the ice " (American Geological I n s t i t u t e , 1974, p. 146). 2 At numerous places, however, the natural b l u f f face is prese n tly covered by a r t i f i c i a l f i l l and/or is fro n te d by a p ro te c tiv e s tru c tu r e . In a few places dolomite bedrock outcrops in the beach zone in Manitowoc, Sheboygan, Milwaukee, and Racine Counties, Wisconsin (Mickelson, e t a l . , 1977, p. 41). 3S c o tt, 1942, n . d . ; M a rtin , 1955; Powers, 1958; Humphrys, Horner, and Rogers, 1958; S t r i e g l , 1958; G iffo rd and Humphrys, 1965; Farrand, 1969; Hands, 1970; Gorder, 1975; E d il, Mickelson, and Acomb, 1977; V a lle jo , 1977; Acomb, e t a l . , 1977; and o thers. 27 form a very lim it e d p o rtio n o f the Wisconsin shoreland studied and these are la r g e ly confined to two small tra c ts near Two Rivers and Sheboygan and both g e n e ra lly d is p la y less than 15 fe e t in lo ca l r e l i e f . Small subdued dunes, g e n e ra lly no more than several fe e t in h e ig h t, also e x is t along a few o th e r backshore segments o f q u ite lim ite d e x te n t. In c o n tra s t, dunal topography occupies a number o f extensive areas along the Michigan shorezone. Here r e la t iv e r e l i e f may exceed 150 fe e t and the dunal tr a c t s may be more than a m ile in width and extend f o r miles along the shore. Furthermore, a v a r ie ty o f eolian forms p o ssibly o f d i f f e r e n t ages may o v e r lie or juxtapose non-dune form ations. Separating the dunal segments are b lu f f s constructed la r g e ly o f d r i f t th a t may approach heights o f 300 fe e t in the northern part o f the study area. Beaches Lake Michigan beaches r e f l e c t lakeshore physiography, wave regimes, lake le v e ls , l i t t o r a l c u rre n ts , and a v a i l a b i l i t y o f sediments. During low water le v e ls beaches may widen considerably (D avis, S e ib e l, and Fox, 1973; Bascom, 1964) and l o w - r e l i e f sand dunes may form in the backshore areas. In c o n tra s t, a t times o f high lake e le v a tio n s , and e s p e c ia lly during intense wave a c t i v i t y , beaches tend to be much narrower or may even be te m p o ra rily e lim in a te d (Davis, S e ib e l, and Fox, 1973; Bascom, 1964). But d iffe re n c e s e x is t between the Michigan and Wisconsin lakeshores; on the average Michigan beaches are wider than those on the west side o f the lake (Krumbein, 1950). Along the Wisconsin lakeshore beach widths seldom exceed 100 fe e t (Krumbein, 1950); th is fig u re is exceeded a t many places along the eastern shore (Hulsey, 1962). Beach sediments range from sand to boulders w ith sand beaches predominating 28 in the Michigan study area (Hulsey, 1962). Sand beaches are also most common in Wisconsin but here coarser p a r t ic l e s , although unevenly d i s t r ib u t e d , tend to comprise a higher p rop o rtio n o f beach segments. Longshore Sand Bars Longshore sand bars occupy the nearshore zone along much o f Lake Michigan. They are most prevalent in the eastern lakeshore (Hands, 1976) but t h e i r e xtent appears to be lim it e d along the Wisconsin reach (Hands, 1970), probably because less sand is a v a ila b le (Saylor and Hands, 1970).^ Numerous in v e s tig a to rs have described these features (Evans, 1940; Davis and McGeary, 1965; Hawley and Judge, 1969; Saylor and Hands, 1970; Davis and Fox, 1972a; Hands, 1976; among o th e rs ). Often continuous f o r m ile s , longshore bars p a r a lle l the strand lin e and g e n e ra lly number two or three but may reach four or f i v e . An ephemeral bar may form c lo s e s t to shore and merge in to the beach face instead o f conforming to the s h o re lin e tre n d . The sand bars seem r e l a t i v e l y unaffected by severe storms (Davis and McGeary, 1965; Davis and Fox, 1971) but t h e i r crests appear to change p o s itio n , e s p e c ia lly w ith v a r ia tio n s in lake le ve l (Evans, 1940; Hawley and Judge, 1969; Saylor and Hands, 1970; Hands, 1976). Apparently these features are o f considerable importance because wave energy is diminished as waves steepen and break over the bars. According to Davis e t a l . (1973) v a r ia tio n s in bar c h a r a c te r is tic s and spacing probably account f o r much o f the d iffe re n c e s in lo c a l rates o f b l u f f recession. ^Davis and Fox (1972a) in d ic a te th a t abundant sand size sediments and a g ra d u a lly slo p in g nearshore bottom are prime p re re q u isite s fo r nearshore sand bars. The Wisconsin b l u f f s , e s p e c ia lly in the southeast, are la r g e ly composed o f fin e -g ra in e d la c u s trin e sediments and s i l t y and clayey t i l l . Consequently, on ly a r e l a t i v e l y small amount o f the m aterial eroded from the shorezone b lu f f s is sand which is able to be re ta in e d in the beach and nearshore zone (Hadley, 1976). 29 Shorezone Ice The Lake Michigan shore normally becomes ic e bound in December w ith the co n d itio n la s t in g u n t i l la te March or A p r i l . Zumberge and Wilson (1953), O'Hara and Ayers (1972), Davis (1973a), Evenson (1973), S e ib e l, Carlson, and Maresca (1976), and Marsh (1977) have in ve s tig a te d t h is phenomenon. With the onset o f w in te r temperatures several conspicuous ice ridges t y p i c a l l y form p a r a lle l to the strand l i n e in the nearshore zone. These are separated by wide areas o f low, rough ice and the whole complex becomes f ir m ly attached to the shore w ith p ortions re s tin g on the lake bottom (Marsh, 1977). During t h is time the beach zone changes from a dynamic to a ne a rly quiescent environment (Davis, 1973a) because waves are unable to reach the beach and shoreland b lu ff. The p ro te c tio n the ice a ffo rd s the b l u f f against wave erosion is im portant because i t is during w in te r when the passage o f cyc lo n ic storms (w ith t h e i r associated waves) is most fre q u e n t. Furthermore, i t is along j u s t those lakeshore reaches w ith the greatest exposure to storm waves, and where nearshore water depths increase only g ra d u a lly , where the la rg e s t ice complexes tend to develop (Marsh, 1977). 30 Lake Level V a riations 5 Lake Michigan's e le va tio n flu c tu a te s in accordance w ith at le a s t three d i s t i n c t time sequences o f d i f f e r e n t magnitudes. Short­ term changes are imposed on seasonal flu c tu a tio n s which in tu rn are superimposed on long-term o s c illa t io n s (In te r n a tio n a l Great Lakes Levels Board, 1973b; Buckler, 1972b; among o th e rs ). Short-term changes la s tin g from a few hours to several days are caused by m eteorological disturbances. For example, winds and d iffe re n ce s in barometric pressure can cause temporary imbalances in the w a te r's a l t i t u d e a t d i f f e r e n t lo c a tio n s although no change in lake volume is in v o lve d . In some places the water e le va tio n can r is e or f a l l more than three fe e t because o f these co n d itio n s. During each year the lake surface flu c tu a te s an average o f 1.1 fe e t in a p re d ic ta b le seasonal cycle ( In te r n a tio n a l Great Lakes Levels Board, 1973b). Runoff from spring snowmelt and r a i n f a l l causes the lake to g ra d u a lly r i s e , reaching i t s y e a rly peak in Ju ly or August. Subsequently, lake le v e ls tend to decrease because o f in cre a sin g evaporation and ge n e ra lly lower r a i n f a l l in la te summer and autumn. 5 H y d ro lo g ic a lly , Lakes Michigan and Huron are considered to be a s in g le u n it because o f t h e i r wide and deep connection a t the S t r a it s o f Mackinac; they have no measurable d iffe re n c e in surface e le v a tio n . At a given time t h e i r water le ve l depends p r im a r ily on whether the lakes are re c e iv in g more or less water than they are lo s in g . The water supply consists o f p r e c ip ita t io n on the lakes' surfaces, r u n o ff from t h e i r drainage areas, in flo w from other la ke s, d ive rsio n o f water in to t h e i r b asins, and ground water in flo w . Water is removed from the lakes by evaporation, dive rsio n to another drainage b a sin , o u tflo w from the lakes through t h e i r natural o u t le t s , and ground water seepage. Approximately 70% o f the contemporary v a r ia tio n in the Lake Michigan-Huron le v e l is re la te d to basin p r e c ip ita t io n (M u lle r, e t a l . , 1965; Brunk, 1960). "Because o f the size o f the Great Lakes and the lim it e d discharge o f t h e i r o u tflo w r i v e r s , extreme high and low le v e ls and flows p e r s is t f o r considerable time a f t e r fa c to rs which caused them have changed" (U.S. Army Corps o f Engineers, 1972, p. 2). 31 The lake ge n e ra lly reaches i t s lowest le ve l between January and March a f t e r fre e z in g temperatures severely re ta rd in flo w o f basin ru n o ff. The 117-year hydrographic record, however, reveals s ig n if ic a n t d iffe re n ce s in y e a rly and seasonal mean le v e ls (Figure 3). Generally, a few consecutive years o f below average lake le v e ls are followed by a number o f years w ith above average e le v a tio n s ; but both the length o f these periods and magnitude o f change are v a ria b le and unpredictable. Differences in annual mean lake elevations r e s u lt p r im a r ily from persistence in below or above average basin p r e c ip ita t io n fo r several years (M u lle r, e t a l . , 1965; Brunk, 1960). These v a ria tio n s in annual p r e c ip ita t io n r e s u lt from changes in mid-to-upper tropospheric a i r flow currents th a t support and guide cyc lo n ic systems across North America (Buckler, 1972b). The average annual le v e l o f the lake surface has varied as much g as 5.62 fe e t since 1860; i f monthly average le ve ls are considered, Lake Michigan's maximum v a r ia tio n is 6.59 fe e t during t h is p e rio d .^ Since the a l l- t im e recorded low in 1964, a tendency toward above average annual p r e c i p it a t io n re s u lte d in a r is e o f the la k e ; 10 years l a t e r , in J u ly , 1974, the water reached an e le v a tio n o f 581.05 f e e t, 2.39 fe e t above i t s long-term (1900-1977) Ju ly average. Although now below i t s 1974 le v e l the lake remains above i t s long-term average. ^Average 1964 fe e t. Freeman (1926) Deep Waterways re p o rt e a r l i e r authenticated been corrected to the Because o f le v e l: 575.66 f e e t ; average 1886 le v e l: 581.28 and Day (1926) c it e the Board o f Engineers on (Secretary o f War, 1900) r e f e r r in g to an even higher le v e l o f 582.56 fe e t ( t h i s fig u re has 1955 IGLD) in 1838. ^March, 1964 le v e l: 575.35 f e e t ; June, 1886 le v e l: 581.94 fe e t. 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 582 Feet 581 Feet 581 Feet 580 Feet 580 Feet - 579 Feet AVERAGE MEAN ANNUAL LEVEL 1860-1977 (- 578 Feet 577 Feet 576 Feet “ MEAN ANNUAL 577 Feet LAKE MICHIGAN WATER LEVELS 1 8 6 0 -1 9 7 7 575 feet Figure 3. AVERAGE MEAN ANNUAL LEVEL 1900-1977 Long-term average annual water le v e ls o f Lake Michigan. 576 Feet 33 g these le v e ls , combined w ith gentle nearshore slopes, beaches have tended to remain r e l a t i v e l y narrow fo r the past decade and considerably diminished from the w ider widths th a t existed during the e a rly 1960's. Winds, Waves, and Currents Wind-generated waves i n i t i a t e most o f the erosion along the Lake Michigan shorezone. Increase in wave s iz e , and th e re fo re wave energy and p o te n tia l erosional a b i l i t y , occurs w ith increase in wind g v e lo c it y , wind duration (from a constant d ir e c tio n ) and fe tc h . Wave development on the lake is probably most r e s tr ic t e d by fetch but the impact o f th is fa c to r varies s i g n i f i c a n t l y because o f i t s north-south o r ie n t a t io n . Due to Lake Michigan's large size and the magnitude o f atmospheric disturbances waves may be produced th a t are comparable in size w ith those observed on many seacoasts (Hough, 1958). There are in d ic a tio n s , though, t h a t a greater amount o f deep water storm wave energy is tra n sm itte d toward the Michigan shore than toward the Wisconsin lakeside ( S a v ille , 1953*, Davis and Fox, 1974). Waves u su a lly approach the shore a t acute angles and as they break they produce longshore currents th a t move p a r a lle l to the s h o re lin e . O Gentle nearshore slopes permit s u b sta n tia l changes in beach w idth w ith r e l a t i v e l y small changes in lake a l t i t u d e . Wide beaches c h a ra cte rize periods o f low lake e le va tio n and narrow beaches t y p i f y times o f r e l a t i v e l y high water le v e ls . 9 Nevertheless, waves can only increase in size to a maximum physical l i m i t . Wind v e l o c i t y , wind duration or fetch can independently se t a wave size l i m i t (King, 1972). For example, ...however long the wind blew a t great speed i t could not generate large waves i f the fe tch were lim it e d . This l i m i t could be imposed e it h e r by the meteorological s i t u a t i o n , which determines the distance over which a wind is blowing in a constant d ir e c t io n , o r by the c o n fig u ra tio n o f the water body, which in some areas determines the fetch a v a ila b le fo r wave generation (King, 1972, p. 46). 34 This action re s u lts in the r e d is t r ib u t io n and subsequent deposition o f sediments introduced in to the nearshore p r im a r ily by waves eroding the shoreland b l u f f s . Beach maintenance and accretio n is la r g e ly dependent on sand supplied by longshore currents and blockage u p d r if t by s tru c tu re s such as groins and harbor j e t t i e s tend to s i g n i f i c a n t l y l i m i t natural sand replenishment. Along both the east and west margins o f Lake Michigan's southern basin net longshore d r i f t is s o u th e rly . But along the northern p o rtio n d r i f t is predominantly northward although reversals in d ir e c tio n occur (Hands, 1970; Seibel , Armstrong, and Alexander, 1976). Storms Strong sustained winds necessary f o r development o f la rg e waves along the Lake Michigan shore are associated w ith c y clo n ic disturbances moving across the Great Lakes region. Although occu rrin g throughout the year these storms are most frequent and intense between la te f a l l and e a rly spring when the p rin c ip a l storm tracks o f the w e s te rlie s are in t h e i r interm ediate and so u th e rly p o s itio n s . The Great Lakes is a p re fe rre d region fo r cy c lo n ic a c t i v i t y during the cold season (Peterssen, 1950) where between November and A p r il two primary storm tra c k s , one o r ig in a t in g over the southwestern United States and the other over western Canada and the northern Rocky Mountain r e g i o n j 0 tend to converge ( K le in , 1957). Seibel (1972) demonstrated t h a t the ra te o f b l u f f recession is not re la te d to the t o t a l number o f storms which pass across the Great Lakes but ra th e r to the la r g e r storms o f the year. For the period ^°These w i l l be re fe rre d to as A lb e rta -ty p e lows. 35 October through February, 1955 to 1976, Rosen (1978; Harman, Rosen, and Corcoran, 1980) determined th a t cy c lo n ic a c t i v i t y was g rea te r in December and January but the highest t o t a l o f "deep" cyclones occurred in November. Also, cyclones o r ig in a tin g over the southwestern United States were the more intense storms, and o f these, the highest percentage took place in November.^ Furthermore, Rosen concluded th a t fo r cyclones to become extremely intense over the Great Lakes they must meet c e rta in c r i t e r i a , namely a sharp a i r mass temperature c o n tra s t, strong support a l o f t , and moist a i r in p u t from the G u lf o f Mexico (provided by o r ig in a t io n in the southwestern United S ta te s ). The absence o f moist G ulf a i r probably accounts f o r the fa c t t h a t although A lb e rta -ty p e lows are the most frequent in the Lake Michigan area in a l l seasons (Cooperman, e t a l . , 1959; Jay Harman, personal communication), the m a jo rity are r e l a t i v e l y weak w ith winds g e n e ra lly i n s u f f i c i e n t to generate d e s tru c tiv e wave action against the shorezone b l u f f s . Commonly i t is the deep low pressure system moving slow ly across the Great Lakes d i s t r i c t from the southwest th a t leads to accelerated wave-cut b l u f f erosion along the Lake Michigan shorezone. Although the cyclone may pass through the area in a n o rth e a s te rly d ir e c tio n the winds and wave regimes i t generates over and along the margins o f the lake w i l l vary depending on the p o s itio n o f the storm c e n te r; consequently, not a l l parts o f the lakeshore come under e s p e c ia lly severe wave a tta c k a t any one tim e. For example, e a s te rly to n o rth e a s te rly winds are t y p i c a l l y associated w ith the leading edge o f these disturbances. I f o f gale fo rc e , they may generate waves th a t ^ T h a t does not mean th a t severe disturbances cannot take place during o th e r months o f the year or o r ig in a te from the northwest. 36 are p a r t i c u l a r l y damaging along the western and southern shorezones. Because o f the p o t e n t i a l ly long fe tch involved the la rg e s t waves to a f f e c t Wisconsin are u s u a lly generated by n o rth e a s te rly storm winds (Hadley, 1976; Mickelson, e t a l . , 1977). Southerly and southwesterly winds are c h a r a c te r is t ic when the center is positioned over the lake. 12 At t h is time the eastern and e s p e c ia lly the northeastern and northern shorezones are p a r t i c u l a r l y vulnerable to wave erosion. The t r a i l i n g edge o f the storm c e ll commonly produces the strongest winds--from the north to northwest (Jay Harmari, personal communication); most o f the severe wave erosion along southeastern Lake Michigan is a tt r ib u t e d to these winds 13 (Davis, Fox, Hayes, and Boothroyd, 1972). Summary The primary force causing b l u f f erosion and recession along Lake Michigan is wave a c t i v i t y during high in t e n s it y storms when lake le v e ls are high. These disturbances are most frequent between October and A p r il and tend to be most severe in November. During times o f low water most o f the energy o f these waves are released on and absorbed by longshore sand bars ( i f present) and beaches f r o n tin g the lakeshore b lu ffs . While some erosion may take place during low and interm ediate lake le v e ls , i t i s accelerated when storm waves are superimposed on high lake le v e ls . During these periods the beaches are narrower or submerged, a llo w in g waves to break close to or d i r e c t l y against the h ig h ly erodable 12 This c o n d itio n also commonly e x is ts on the leading edge o f an A lb e rta -ty p e low moving across the western Great Lakes. 13 North to west winds are also t y p i c a l l y associated w ith the t r a i l i n g edge o f A lb e rta -ty p e lows as they pass through the western Great Lakes d i s t r i c t . 37 unconsolidated b lu f f s . Under such conditions t h e i r bases may be ra p id ly undercut, leading to i n s t a b i l i t y and eventual f a i lu r e o f the slopes and recession o f the b l u f f c re s ts . Regardless o f Lake Michigan's le ve l the high frequency o f large storms during the f a l l season (and to a lesser extent the spring season) commonly does not allow the beach to f u l l y recover during the low energy conditions between storms (S e ib e l, Armstrong, and Alexander, 1976). Consequently, erosion , or a t le a s t the p o te n tia l fo r e rosion , may become p rog re ssive ly more acute as the storm season advances. B l u f f e rosion , however, is gen e ra lly minimal during the w in te r and summer seasons. The b u ild -u p o f shorezone ice a ffo rd s a tim e ly p ro te c tiv e b a r r ie r against w in te r storm waves. And because summer is t y p i c a l l y a low energy period beaches a t t h is time c h a r a c t e r is t ic a lly reach t h e i r widest annual w idths. Large summer storms are not common but when they do occur, and even though waves are superimposed upon the highest annual water le v e l , the beaches are generally s u f f i c i e n t to d is s ip a te the incoming wave energy w ith o u t serious damage to the b l u f f . Following the disturbance there is u s u a lly enough time before another summer storm occurs f o r the beach to recover f u l l y . Chapter 3 SITE CHARACTERISTICS, RATES AND SPATIAL VARIATIONS OF LONG-TERM BLUFF RECESSION, AND RELATIONSHIP OF SELECTED VARIABLES TO BLUFF RETREAT In tro d u c tio n B l u f f Crest Recession and B l u f f Erosion B l u f f c re s t recession is " e s s e n tia lly a geometric concept, in v o lv in g the landward displacement o f . . . b l u f f lin e s " and b l u f f erosion " is a mass concept in v o lv in g the net removal o f b l u f f m a te ria l" (Pincus, 1962, p. 124). Although they may take place sim ultaneously, one can occur w ith o u t the o t h e r J The time lag between i n i t i a t i o n o f basal erosion and c re s t recession may range from seconds to several hours, months, or years and, f o r some high b l u f f s , perhaps even more than one episode o f high lake le v e ls . B l u f f c re s t recession is the primary i n t e r e s t in t h is study because i t most d i r e c t l y a ffe c ts develop­ ment o f the shoreland surface. Long-Term and Short-Term B l u f f Recession In t h is study long-term b l u f f l in e recession represents losses in cu rre d over an in t e r v a l o f a t le a s t 120 years whereas s h o rt-te rm r e tr e a t gen e ra lly represents a period o f two decades o r le s s . Recession rates a t a given lo c a tio n may vary during d if f e r e n t length periods but V o r example, storm waves may remove the base o f a cohesive t i l l b l u f f slope w ith o u t i n i t i a t i n g a simultaneous movement o f the b l u f f c re s t. Or, ir r e s p e c tiv e o f recent storm waves, the c re s t may recede due to f a i l u r e and slumping o f the upper slope; the slope p r o f i l e would change but there would be l i t t l e net loss o f b l u f f m a te ria l. 38 39 these changing co n d itio n s may be obscured by long-term recession values. Consequently, estimates o r p ro je c tio n s based on these long-term values may not be a p p lic a b le f o r s h o rte r time spans, e s p e c ia lly i f these periods coincide w ith e it h e r a low or high lake stage. For example, some o f the b l u f f s ite s in t h is in v e s tig a tio n have undergone considerable losses during the la s t 12 years y e t t h e i r long-term average annual recession rates are r e l a t i v e l y low, and a t some sand dune lo c a tio n s net accretion has even occurred. Likewise, i t may be misleading to p re d ic t long-term shorezone e v o lu tio n s o le ly on changes ta k in g place over only several years or a s in g le decade. Spacing and Point Nature o f the S ites Long-term b l u f f recession rates are based on data from 118 s ite s t h a t a re , w ith two exceptions, a minimum o f one mile a p a rt, but t h is distance is commonly g re a te r and spacing tends to be uneven. Being s h o rte r in length but e n t a ilin g more s ite s (52) the Wisconsin lakeshore is more uniform ly sampled than the Michigan shorezone where s ite s (56) tend to be more w id e ly spaced (Figure 4 ). T h e o r e tic a lly each s it e is represented by a s in g le p o in t along the b l u f f . Because o f the wide s p a tia l and temporal v a r ia tio n in b l u f f recession the p o s itio n o f the b l u f f lin e and i t s rate o f r e tr e a t may not n e ce ss a rily be representative o f nearby b l u f f segments, e s p e c ia lly on a s h o rt-te rm basis. Nevertheless, c o lle c t io n o f data and i d e n t i f i c a t i o n o f long-term patterns and r e l a t i o n ­ ships concerning Lake Michigan b l u f f recession and shorezone e v o lu tio n is ^ p o s s ib le because o f the large number and v a r ie ty o f s ite s in v e s tig a te d . Furthermore, although conclusions are based on measured data from 118 section l in e s i t e s , f i e l d and a e ria l photographic observations a t numerous other lo c a tio n s lend support to the premises presented. 40 LO N G -TERM AVERAGE ANNUAL BLUFF LINE CHANGES Sheboygan A le ga n -J Figure 4. S ite lo c a tio n s and t h e i r long-term average annual b l u f f l i n e changes. 41 S ite C h a ra c te ris tic s The range in c h a r a c te r is tic s o f the 118 s ite s r e fl e c t s the v a r ia tio n in Lake Michigan shorezone physiography ( s it e d e scriptio n s are summarized c o n s is t in Appendix B). S ix ty percent o f the Michigan s ite s o f b lu f f s composed e n t i r e l y o f dune sand or o f dune sand o v e rly in g o th e r sediments. These co n ditions e x is t a t only 16% o f the Wisconsin s ite s and most o f these are concentrated in southern Sheboygan County. At the study lo c a tio n s dune sand reaches thicknesses as great as 50 fe e t in Michigan but never more than f iv e fe e t in Wisconsin. A greater p ro p o rtio n o f the Wisconsin s ite s include b l u f f s o f various non-eolian Quaternary m a te ria l. Both permeable and r e l a t i v e l y impermeable sediment zones occur in 36 o f the 62 Wisconsin b lu f f s but are found a t only 19 o f the 56 s ite s in Michigan. Ground water discharge is e s p e c ia lly common where permeable s tra ta o v e r lie r e l a t i v e l y impermeable m a te ria l. This c o n d itio n has im portant geomorphic im p lic a tio n s because ground water seepage may c o n trib u te s i g n i f i c a n t l y to b l u f f slope f a i l u r e . In Wisconsin b l u f f heights a t the s ite s vary from one to 120 f e e t , w ith b lu f f s a t 16 l o c a l i t i e s under 10 fe e t and s ix a t 100 fe e t o r g re a te r. Low la c u s tr in e terraces adjacent to the s h o re line account f o r these numerous low b l u f f lo c a tio n s . B l u f f s ite s in Michigan range from s ix to 310 fe e t in h e ig h t, w ith only f iv e under 10 fe e t but e ig h t over 100 fe e t. During the present high lake stage (Figure 3) appreciable erosion o f the b l u f f base has occurred a t 57 o f the 62 Wisconsin s ite s and a t 53 o f the 56 Michigan lo c a tio n s . In c o n tra s t, at 12 o f the section lin e s in Wisconsin and a t 16 in Michigan b l u f f c re s t r e tr e a t had been n e g lig ib le or n o n -e x is te n t during t h is p e rio d , even though many have undergone considerable recession during the l a s t 120 years o r more. 42 Rates o f Long-Term B l u f f Line Change 2 Data from a t le a s t 106 o f the 118 section lin e s ite s in both Wisconsin and Michigan show long-term b l u f f c re s t recession. For the period studied the average annual r e tr e a t fo r these 106 lo ca tio n s is 1.43 fe e t (0.436 m) but net losses range from as l i t t l e as 3.64 fe e t (1.11 m; s i t e M56) to as much as 1066.32 fe e t (325 m; s i t e W1). Eight other s it e s , however, show long-term a c c re tio n , varying from a net gain o f 6.45 fe e t (1.97 m; s it e W34) to 104.25 fe e t (31.78 m; s i t e M40). Table 1 summarizes the v a r ia tio n in average annual b l u f f c re s t changes and Tables Cl and C2 (Appendix C) show the s it e lo ca tio n s and corresponding recession and accretion data. Spatial V a ria tio n in B l u f f Line Changes In d iv id u a l s ite s and extended reaches w ith in both the Wisconsin and Michigan study areas d is p la y a wide v a r i a b i l i t y in b l u f f lin e changes (Figure 4 and Tables 1, C l, and C2). But co n tra ry to expectation o v e ra ll average annual long-term b l u f f c re s t recession f o r the two lakeshores is s im ila r . Analysis o f data from the d i f f e r e n t shorelines using Student's t^ te s ts in d ic a te s t a t i s t i c a l l y no s i g n if ic a n t d iffe re n c e (a t the .05 s ig n ific a n c e le v e l) in the two sample populations (Table 2 ). At four Michigan sand dune s ite s (M23, M31, M36, and M53) two d i s t i n c t b l u f f cre sts are recognized. The lakeward c re s t is a b l u f f l in e o f a l o w e r - r e l i e f dune te rra ce which fro n ts the more landward c re s t o f a somewhat h i g h e r - r e l i e f dune fe a tu re . At these lo ca tio n s i t was unclear as to which c re s t the resurvey should be c a rrie d to in order to compare i t w ith the o r ig in a l GL0 measurements. Therefore, values are reported based on both possible b l u f f l in e p o s itio n s . In three o f the fo u r cases measurements to e it h e r c re s t in d ic a te d only small net changes in b l u f f l i n e p o s itio n r e la t iv e to the GL0 survey. The recession or accretion rates determined f o r these fo u r s ite s are not included in any o f the q u a n tita tiv e analysis performed in t h is study. In no way does t h is exclusion a f f e c t the conclusions reached and, in f a c t , t h e i r in c lu s io n would on ly increase support f o r the fin d in g s reported. 43 Table 1. V a ria tio n in long-term average annual rates o f b l u f f li n e change a t the Wisconsin and Michigan study s i t e s . 3 Wisconsin Michigan Total Number o f Sites B l u f f Sites Which Experienced Recession: Average Annual Recession less than 0.51 f t . to 1.01 f t . to 1.51 f t . to 2.01 f t . to 2.51 f t . to 3.01 f t to 3.51 f t . to g rea te r than 0.50 1 .00 1.50 2.00 2.50 3.00 3.50 4.00 4.01 ft. ft. ft. ft. ft. ft. ft. ft. ft. 14 12 11 6 4 7 1 0 3 8 15 8 8 4 4 0 0 1 22 27 19 14 8 11 1 0 4 3 1 0 0 0 2 0 2 3 3 0 2 B l u f f Sites Which Experienced A c c re tio n : Average Annual Accretion less 0.21 0.41 0.61 than ft. ft. ft. to to to 0.20 0.40 0.60 0.80 ft. ft. ft. ft. Average Annual Rate o f Long-Term B l u f f Recession 1.43 f t . (0.436 m) 1.16 f t . (0.354 m) 1.31 f t . (0.399 m) Normalized15 Average Annual Rate o f Long-Term B l u f f Recession 1.15 f t . (0.351 m) 1.10 f t . (0.335 m) 1.13 f t . (0.344 m) The double-crested Michigan dune s ite s M23, M31, M36, and M53 are not included in t h is t a b le ; see footnote 2. The maximum average annual b l u f f li n e changes f o r these fo u r s ite s varied between +0.77 fe e t (+0.235 m) and -0.47 fe e t (-0 .1 4 3 ). Extreme cases were e lim in a ted by considering only those s ite s where rates are w ith in two standard deviations o f the mean ra te . Table 2. Results o f Student's _t te s ts in d ic a tin g th a t s t a t i s t i c a l l y there is no s i g n if ic a n t d iffe re n c e (a t the .05 s ig n ific a n c e le v e l) in the o v e ra ll rates o f long-term average annual b l u f f c re s t recession between t.he Wisconsin and Michigan study s it e s . Sample Group # of Cases Mean Rate Wisconsin Sites 62 1.432' Std. Dev. Var­ iance Std. Error 1.553 2.412 .197 Student's t .255 Michigan Sites Wisconsin Sites (normalized9 ) Michigan Sites (normalizeda ) 52 1.159' 0.963 0.927 .134 59 1.151' 0.930 0.865 .121 .757 51 1.098' 0.863 0.745 .121 aExtreme cases were e lim inated by considering on ly those s ite s where rates are w ith in two standard de via tio n s o f the mean ra te . 45 Although the simple mean rate f o r each shoreland is d i f f e r e n t , 1.43 fe e t (0.436 m) per year f o r Wisconsin and 1.16 fe e t (0.354 m) annually f o r Michigan, when the values are normalized to e lim in a te extreme cases by considering on ly those s ite s whose rates are w ith in two standard deviations o f the mean both shorezones then d isp la y very s im ila r rates o f b l u f f c re s t r e t r e a t : an average o f 1.15 fe e t (0.351 m) y e a rly fo r the Wisconsin b lu f f s and 1.10 fe e t (0.335 m) annually f o r those in Michigan. Sites in southern p ortions o f both lakeshores g e nerally e x h ib it higher than average b l u f f li n e losses. In Wisconsin b l u f f crests a t s ite s south o f Port Washington (Ozaukee County) have receded at rates s i g n i f i c a n t l y d i f f e r e n t from those to the north o f the c i t y (Table 3 and Figure 4). Although values vary appreciably w ith in each reach recession rates to the south ( s ite s W1-W26), which when normalized average 1.84 fe e t (0.561 m) a n n u a lly, are much more l i k e l y to be higher than those to the north ( s ite s W27-W62) where mean r e tr e a t is only 0.71 fe e t (0.216 m). In Michigan the southern reach i d e n t if ie d by c o n s is te n tly high s i t e values is r e s t r ic t e d mostly to Berrien and Van Buren counties. But u n lik e s ite s in i t s Wisconsin c o u n te rp a rt, study lo c a tio n s here do not include re presentatives o f a l l major shore­ land types encountered w it h in the area; although much o f t h is zone consists o f sand dunes, no study s ite s occur in dune lo c a tio n s . Furthermore, whereas s ite s along the northern Wisconsin shorezone d isp la y losses g e n e ra lly lower (but s t i l l varying) than to the south, The e x c e p tio n a lly high losses in cu rre d a t s it e s W1-W3 were disregarded as t h e i r rates are not w it h in two standard deviations o f the mean r a te . I f t h e i r values are included then the mean r e tr e a t ra te f o r the southern lakeshore is 2.43 fe e t (0.741 m) annually. 46 Table 3. Results o f Student's t te s ts in d ic a t in g th a t s t a t i s t i c a l l y there is a s i g n i f i c a n t d iffe re n c e (a t the .05 s ig n ific a n c e le v e l) in the long-term average annual b l u f f c re s t recession rates between the Wisconin s it e s south o f Port Washington (Ozaukee County) and those north o f the c i t y . Sample Group # of Cases Mean Rate Std. Dev. Var­ iance Std. Error Sites South o f Port Washington 26 2.431' 1.883 3.546 .369 Sites North o f Port Washington 36 0.710' 0.624 0.389 .104 23 1.841' 0.916 0.845 .192 Sites South o f Port Washington (normalizeda ) Sites North o f Port Washinton (normalizeda ) Student's t .000 .000 36 0.710' 0.624 0.389 .104 aExtreme cases were elim in a ted by considering only those s ite s where rates are w ith in two standard d e via tio n s o f the mean ra te . 47 Michigan s ite s north o f Van Buren County are less l i k e l y to reveal t h is same r e la tio n s h ip . Several segments o f both lakeshores have b l u f f lin e s th a t are experiencing e it h e r e s p e c ia lly high o r p a r t i c u l a r l y low long-term changes (Figure 4 ) . 4 These segments contain a comprehensive v a r ie ty o f shore and shoreland c h a r a c te r is tic s found w it h in the study areas. In southern Wisconsin three shorezone stre tch e s are i d e n t i f i e d as having sustained unusually high b l u f f c re s t recession; an equal number north o f Port Washington have experienced very low losses. And three areas undergoing e x c e p tio n a lly high r e t r e a t and one zone su sta in in g minimal recession are recognized in Michigan. Representative Areas o f High B l u f f Recession Wisconsin B l u f f c re s t recession is highest at s ite s (W1-W3, Figure 4) along the southern most 3.5 miles o f the Wisconsin lakeshore. Here a b l u f f f r o n tin g a low la c u s trin e te rra ce (Figure 5) has re tre a te d at an average ra te o f 6.95 fe e t (2.118 m) per year. Oriented somewhat west o f north the s h o re lin e is exposed to waves generated by the p o t e n t ia lly more damaging n o rth e a s te rly storm winds which may tra v e l over a fetch g reater than 250 m ile s. Generally unprotected p r i o r to 1955 (U.S. Army Corps o f Engineers, 1955) shorezone p ro te c tio n s tru c tu re s now average approximately 42 per m ile (Mickelson, e t a l . , 1977) and appear to account f o r the wide v a r ia tio n in beach widths encountered over s h o rt dista n ce s. ^Nevertheless, w ith in each o f these segments recession rates a t in d iv id u a l s ite s may s t i l l vary ap p re cia b ly. Furthermore, these reaches are not in c lu s iv e ; c e r t a in ly many o th e r zones o f comparable d is t in c t io n go unrecognized. 48 Figure 5. The shorezone a t s it e W3, South Line / Section 17 / T1N,R23E, Kenosha County, Wisconsin. Average annual b l u f f recession between 1835 and 1976 is 6.33 fe e t (1.929 m). This photo was taken on September 19, 1976. 49 Averaging 2.54 fe e t (0.774 m) y e a rly b l u f f recession is also r e l a t i v e l y high at three adjacent section lin e s ite s (W5-W7, Figure 4) along the northern two miles o f Kenosha County. This segment comprises an area discussed in d e ta il in Chapter 4. The 30 to 35 fo o t high b lu f f s are composed p r im a r ily o f w a te r- la id sands over c la y and/or till; ground water commonly discharges from the base o f the sand s tra ta a t the b l u f f face. P ro te c tive s tru c tu re s are numerous along the shoreline which is o rie n te d about 15 degrees east o f n o rth . A t h ir d area o f high b l u f f c re s t recession extends e ig h t miles north from a p o in t about two miles north o f the Milwaukee-Ozaukee county li n e . Long-term r e tr e a t a t e ig h t s ite s (W18-W25, Figure 4) w ith in th is t r a c t averaged 2.41 fe e t (0.735 m) annually. B lu ffs are h ig h , 75 to 140 f e e t, and are constructed o f interbedded t i l l s , c la y s , and w a te r- la id sands and gravels. Ground water seeps are numerous and along many p o rtio n s the b l u f f face is la r g e ly tre e covered. Evidence o f slumping is widespread on the slopes and appears to have accounted d i r e c t l y f o r b l u f f c re s t recession a t many lo c a tio n s . At the b l u f f base i t is large slump blocks th a t commonly experience storm wave erosion (Figure 6 ). Whereas the upper slopes o f some s ite s have undergone s i g n if ic a n t a lt e r a tio n s since 1968 others seem to have been r e l a t i v e l y sta b le fo r q u ite some time. Mi chi qan Accelerated long-term b l u f f recession has taken place along at le a s t two segments o f the Berrien County shorezone. the Shoreham lakeside a case study. One reach encompasses which is in v e s tig a te d more f u l l y in Chapter 4 as B lu ffs vary in height from about 40 to 75 fe e t and co n sist la r g e ly o f w a te r- la id sands and gravels except along the northern 50 •4 & ^ i . .y . (B) ..... IHRP** Figure 6. B l u f f recession r e s u ltin g from wave erosion and mass-wasting. The photos were taken in August, 1977 in Section 4 / T9N,R22E, approximately 750 fe e t south o f s i t e W22 (South Line / Section 33 / T10N,R22E), Ozaukee County, Wisconsin. (A) In 1967 an 85 fo o t wide and 300 fo o t long section a t the top o f a 115 fo o t high b l u f f slumped down approximately 50 f e e t , although the block never reached the beach. Minor slumping along the top edge has continued to the present. (B) At the base o f the b l u f f storm waves have eroded a 20-30 fo o t n ip in t o another slump block. 51 o n e -th ird mile where cla y and/or t i l l e la s t ic s . are interbedded w ith coarser For two s ite s (Ml and M2, Figure 4) long-term recession averages 2.02 fe e t (0.616 m) annually but recent rates along th is lakeshore have been much g rea te r. Mean y e a rly b l u f f l in e losses o f 4 .3 0 ,^ 2.92, and 2.39 fe e t (1.311, 0.890, and 0.728 m) are recorded fo r s ite s (M4, M5, and M6, re s p e c tiv e ly ) w ith in a three m ile s tre tc h o f high b lu f f s beginning approximately three miles northeast o f the St. Joseph-Benton Harbor je ttie s . W ate r-la id sands o v e rla in by t i l l and in some places topped by another r e l a t i v e l y th in zone o f w a te r - la id sands e x is t in these 70 to 120 fo o t b l u f f s . Slumping, r i l l i n g , and g u lly in g are common on the slopes (Figure 7). During the present high water period erosion o f the b l u f f face has been severe a t the southern two s ite s although only reaching the c re s t a t lo c a tio n M4. A foredune, since removed by storm wave a c t i v i t y , had fro n te d the b l u f f at the northern section lin e and apparently delayed the onset o f wave erosion on the b l u f f slope. One-half m ile south o f the Manistee harbor j e t t i e s 60 to 70 fo o t b lu f f s ( t i l l over w a te r - la id sands) have been receding r a p id ly along a 1.5 miles n o rth -n o rth e a s te rly tre n d in g s h o re lin e . Long-term losses a t two s ite s amounted to 1.91 and 2.65 fe e t (0.582 and 0.808 m, s ite s M43 and M44, r e s p e c tiv e ly ; Figure 4) a n n u a lly. This high recession zone a b ru p tly ends a t and southward o f the South Line / Section 15 / T21N,R17W ( s it e M42) where foredunes have p re v io u s ly formed and appear to be p ro te c tin g adjacent b lu f f s from accelerated r e t r e a t (Figure 8 ). 5 The rate at lo c a tio n M4 is probably somewhat higher than the adjacent b l u f f zone because the section l i n e here has in te rc e p te d the b l u f f lin e a t an acute angle where extensive slumping and g u lly in g have occurred. 52 * 49 ^ Figure 7. The shorezone at s it e M4, North Line / Section 6 / T4S,R18W, Berrien County, Michigan. Average annual b l u f f l i n e recession between 1830 and 1977 is 4.30 fe e t (1.311 m). The elevated beach house was constructed sometime between 1975 and 1977. This photo was taken on August 29, 1978. 53 Figure 8. The shorezone a t s ite s M42 (extension o f the road on the r i g h t ) , South Line / Section 15 / T21N,R17W, and M43 ( l e f t ro a d ), C e n te rlin e / Section 15 / T21N,R17W, Manistee County, Michigan. Average annual b l u f f recession between 1839 and 1977 a t s i t e M42 is 0.52 fe e t (0.158 m); here foredunes have formed. Mean y e a rly b l u f f r e t r e a t a t s i t e M43 between 1847 and 1977 is 1.91 fe e t (0.582 m). This photo was taken on June 19, 1978. 54 Representative Areas o f Low B l u f f Recession Wisconsin Sites along a n o rth -n o rth e a s te rly trending sh o re lin e from approximately Belgium Township (T12N) in northern Ozaukee County northward to the middle o f Wilson Township (T14N) in southern Sheboygan County ( s ite s W27-W35, Figure 4) have experienced r e l a t i v e l y little long-term recession. d i s t i n c t zones. This reach may be divided in t o two The southern p o rtio n to the Ozaukee County l in e is being developed on a N ip is s in g age lake te rra ce (Figure 9 ). Beach widths were in the 20 fo o t range in the summer o f 1976 but residents re p o rt sand beaches 200 fe e t wide in the past (Hadley, e t a l . , 1977). A 20 fo o t wide bedrock s h e lf was exposed lakeward o f the beach a t water le v e l a t several places (Acomb, e t a l . , 1977; t h is s tu d y ). And, as along the northern p o r tio n , three sand bars were evident in the nearshore zone.® A lake te rra ce also forms the northern segment but the backshore is chara cte rize d in most lo ca tio n s by o ld beach ridges and l o w - r e l i e f sand dunes; beaches were gen e ra lly wider than to the south (Figure 10). In some areas foredunes reported by Powers (1958) in 1956-57 are no longer evident or appear to be reduced s i g n i f i c a n t l y in w id th . Shoreland recession ranging from 0.5 to 3.0 fe e t (0.152 to 0.914 m) per year occurred between 1967 and 1977 at several places (Hadley, e t a l . , 1977) but mean annual long-term r e tr e a t has been much le s s , averaging 0.35 fe e t (0.107 m) f o r s ix s ite s considered in t h is study. Furthermore, three sand dune associated s ite s have even shown net a c c re tio n , averaging 0.16 fe e t (0.046 m) annually. Sand bars are uncommon along most segments o f the Wisconsin study area. Figure 9. The shorezone a t s i t e W27, South Line / Section 25 / T12N,R22E, Ozaukee County, Wisconsin. Average annual b l u f f recession between 1835 and 1976 is 0.12 fe e t (0.037 m). This photo was taken on July 9, 1976. 56 Figure 10. The shorezone a t s i t e W35, South Line / Section 14 / T14N,R23E, Sheboygan County, Wisconsin. Average annual net a c cre tio n a t t h i s sand dune lo c a tio n is 0.06 fe e t (0.018 m) f o r the period between 1835 and 1976. This photo was taken on August 12, 1976. 57 A second area w ith low rates o f r e tr e a t e x is ts in southern Manitowoc County and extends from midway in C e n te rv ille Township (T17N) northward to w ith in one mile o f the northern boundary o f Newton Township (T18N). Average y e a rly recession rates a t s ix s ite s (W44-W49, Figure 4) range from 0.17 to 0.76 fe e t (0.052 to 0.232 m). c o n s is ts , in general, o f t i l l B l u f f s tra tig r a p h y o v e rla in by w a te r- la id sands and gravels which include cla y zones a t some lo ca tio n s (Figure 11). B l u f f heights a t the s ite s range from 27.5 to 55 fe e t and sh o re line o r ie n ta tio n varies between N5°E and N25°E. Ground water seeps e x is t at the base o f the sands and gravels in some places and evidence o f slumping is common, although o fte n not in v o lv in g the f u l l face o f the b l u f f . B l u f f lin e changes are also r e l a t i v e l y small a t Kewaunee County s ite s in a zone beginning about two miles north o f the Kewaunee harbor s tru c tu re s and extending to approximately 1.5 miles south o f the Algoma je ttie s . These changes vary from + 0.08 fe e t (+ 0.024 m) a year in the north to - 0.77 fe e t ( - 0.235 m) in the south w ith an o v e ra ll long-term recession rate averaging 0.28 fe e t (0.085 m) annually f o r f iv e s ite s (W57-W61, Figure 4 ). are composed o f t i l l Along the southern f iv e miles 40 to 60 fo o t b lu f f s and sand and grave l. Slumping is common a t the base o f the slopes but in many places is not apparent w ith in the upper p a rt o f the b l u f f (Figure 12). In c o n tra s t, a l o w - r e l i e f lake te rra ce forms the northern two miles o f t h is low recession zone (Figure 13). Mi chi gan Sand dunes are present a t a l l Michigan s ite s where long-term average annual b l u f f l i n e losses are less than 0.50 fe e t (0.152 m). The 1.75 m ile shorezone segment between the o u tle ts o f North and South Bar Lakes in Leelanau County (Empire Township, T28N) is re p re se n ta tive Figure 11 59 Figure 12. The b l u f f a t s i t e W60, South Line / Section 16 / T24N,R25E, Kewaunee County, Wisconsin. Average annual b l u f f recession between 1834 and 1976 is 0.22 fe e t (0.067 m). This photo was taken on August 7, 1976. 60 Figure 13. The lake te rra c e forming the shore!and along section 34 o f Ahnapee Township (T25N) and sections 3 and 10 o f Pierce Township (T24N), Kewaunee County, Wisconsin. S ite W61 (North Line / Section 3 / T24N,R25E) is a t the clump o f tre e s on the te rra c e i n the upper center p a rt o f the photo; measurements here in d ic a te an average a c cre tio n value o f 0.08 fe e t (0.024 m) annually f o r the period 1834 to 1976. This photo was taken on J u ly 12, 1976. 61 o f these lo c a tio n s . Mean y e a rly recession rates o f the 13 to 15 fo o t high dunes^ a t the two study s ite s are only 0.06 and 0.34 fe e t (0.018 and 0.104 m; s ite s M51 and M52, r e s p e c tiv e ly ) . In 1968 foredunes th a t formed during the low water period o f the la te 1950's anti e a rly 1 960's fro n te d the more landward b lu ff s b u t, because o f r i s i n g lake le v e ls , by 1975 wave erosion had removed most o f them and p ro te c tiv e s tru c tu re s had been constructed along some lo t s (Figure 14). With a s l i g h t drop in lake e le v a tio n in 1977 a beach again developed and blowing sand began to accumulate in the backshore area. Based on these re pre se n ta tive areas i t is apparent th a t many s ite s experiencing s im ila r rates o f long-term b l u f f recession have d i f f e r i n g c h a r a c t e r is t ic s , and th a t some w ith s i m i l a r i t i e s vary s i g n i f i c a n t l y w ith respect to t h e i r recession ra te s . In the fo llo w in g sections selected varia bles are examined to determine i f they have c le a r a ssociations w ith long-term r e tr e a t ra te s . The R elationship o f Sand Dunes and B l u f f Recession M aterials comprising the b l u f f s it e p r o f il e s are grouped in to fo u r general sedimentary ca te g o rie s: dune sand, w a te r- la id sand, c la y , g and t i l l . On t h is basis more than 20 d i f f e r e n t arrangements o f sediments ^R elative r e l i e f between the two study s ite s is g re a te r, however. O Dune sand: e o lia n deposits o f sand size p a r t ic l e s ; in th is study dune sand is synonymous w ith wind-blown sand, e o lia n sand, e olian sediment, e o lian d e p o s it, or e o lia n m a te ria l. W a te r-la id sand: water-deposited sand size p a r t i c l e s , w ith and w ith o u t pebbles, and may include t h in interbedded zones w ith high percentage o f c la y o r s i l t size p a r t ic le s . Clay: water-deposited sediments o f a c la y or s i l t y - c l a y te x tu re . T ill: non-sorted g l a c i a l l y deposited sediments which in the study areas are normally o f a cla y loam t e x tu r e ; pebbles and cobbles are almost always present. C o lle c t iv e ly , w a te r - la id sand, c la y , and t i l l may be re fe rre d to as non-sand dune (Quaternary) sediment or m a te r ia l, or non-eolian (Quaternary) sediment or m a te ria l. 62 Figure 14. The shorezone in 1968 and 1977 a t s i t e M51, South Line / Section 13 / T28N,R15W, Leelanau County, Michigan. (A) In 1968, when the lake again began to r is e above average, low foredunes, formed during the low water period o f the la t e 1950's and e a rly 1960's, fronted the more landward dune b l u f f s . (B) Because o f the above average water conditions by 1975 storm waves had eroded most o f the foredunes. But w ith a s l i g h t drop in le ve l by 1977 a beach had again developed. The seawall and groin system in the center o f the photo was in s t a lle d in the spring o f 1974 and a t the time stood s ix fe e t above the sand and i t s lakeward end was in two fe e t o f w ater; by July 26, 1977 beach a ccre tio n had almost buried i t . 63 I'"'** ' • **(*•* (B) Ju ly 26, 1977 Figure 14 ( c o n t 'd . ) - 64 can be i d e n t i f i e d . V a ria tio n s in long-term average annual recession rates could not be re la te d in a meaningful way to s p e c ific sedimentary types or r e la tio n s h ip s f o r s ite s where b lu f f s are formed o f non-eolian m a te ria l. Furthermore, although in Michigan the mean r e tr e a t rate f o r these non-dune b lu f f s is s l i g h t l y higher and in d iv id u a l s it e values are somewhat less v a ria b le than in Wisconsin, Student's t_ te s ts in d ic a te s t a t i s t i c a l l y no s ig n i f i c a n t d iffe re n c e in b l u f f recession rates between the two lakeshores (Table 4 ). There i s , however, a notable d i s s i m i l a r i t y in recession rates between b lu f f s formed o f non-dune m aterial and those composed o f dune sand, and dune sand underlain by w a te r - la id sand. 9 Analysis based on the d iffe re n c e o f means t_ t e s t ( a t the .05 s ig n ific a n c e le v e l) im p lie s t h a t , o v e r a l l , these sand dune encompassed b l u f f s ^ have receded a t a s i g n i f i c a n t l y lower annual ra te than have b lu f f s composed o f non-eolian sediments, 6, 7, and 8 ). 11 whether in Michigan or Wisconsin 12 (Tables 5, Moreover, between the Wisconsin and Michigan lakeshores these rates are s t a t i s t i c a l l y s im ila r (Table 9 ). 9 At some lo c a tio n s w a te r - la id sand is exposed a t the base o f an otherwise sand dune b l u f f . During average or low water conditions the w a te r - la id sand may be la r g e ly obscured by foredunes but during high lake le v e ls wave erosion reveals i t s existence. In Wisconsin t h is w a te r-la id sand is seldom th ic k e r than a few fe e t but in Michigan i t may represent a zone up to several tens o f fe e t in thickness. The surface o f the waterla id sand probably represents the shore zone on which the dune sand was i n i t i a l l y deposited. Because t h is surface is in c lin e d and is at a higher e le v a tio n than the present lake l e v e l , wave erosion over hundreds or thousands o f years has exposed the w a te r - la id sand. (These b lu ff s o f dune sand underlain by w a te r - la id sand do not r e fe r to the c la s s ic a lly defined "perched sand dunes" located along portions o f the northern reach o f the Michigan study a re a .) ^Sand dune encompassed b lu f f s r e fe r to a combination o f those b lu f f s composed e n t i r e l y o f dune sand and those formed by dune sand under­ l a in by w a te r - la id sand. ^ F o r example, o f the 25 Michigan b l u f f s ite s w ith the lowest long-term recession r a te s , 18 c o n s is t e n t i r e l y o f dune sand and fiv e are composed o f dune sand underlain by w a te r- la id sand. 65 Table 4. Results o f Student's t. te s ts in d ic a t in g th a t s t a t i s t i c a l l y there is no s ig n i f i c a n t d iffe re n c e ( a t the .05 s ig n ific a n c e le v e l) in the o v e ra ll rates o f long-term average annual recession between Wisconsin and Michigan non-sand dune b l u f f s ite s . Sample Group Wisconsin Non-Dune Sites Michigan Non-Dune Sites Wisconsin Non-Dune Sites (normalizeda ) Michigan Non-dune Sites (normalizeda ) # of Cases Mean Rate Std. Dev. Var­ iance Std. Error 52 1.611' 1.602 2.566 .222 Student's ;t .759 23 1.701' 0.912 0.832 .190 49 1.284' 0.905 0.819 .129 22 1.583' 0.731 0.534 .156 .146 aExtreme cases were elim in a ted by considering on ly those s ite s where rates are w ith in two standard devia tio n s o f the mean ra te . Table 5. Comparison o f long-term average annual rates o f recession between b lu f f s encompassing dune sand and b lu f f s composed o f non-dune sediments, Long-Term Average Annual Rate o f B lu f f Crest Recession Number o f Sites Wisconsin 62 59 2 Michigan 52 51 20 Wisconsin and Michigan 114 110 22 Wisconsin Michigan Wisconsin and Michigan 1.43' 1.16* 1.31' (0.436 ml (0.354 ml (0.399 ml A ll Sites 1.15' 1.10' 1.13' (normalized3 ) (0.351 m) (0.335 ml (0.344 ml Sand Dune Sites 0.02' 0.60' 0.55' (0.183 ml (0.168 ml 0.62' 1.01' 0.82' (0.189 m) (0.308 ml (0.250 ml 0.50' 0.73' 0.67' (0.152 m) (0.223 ml (0.204 ml 1.61’ 1.70' 1.64' (0.491 m) (0.518 m) (0.500 m) Non-Sand Dune Sites 1.28' 1.58' 1.38' (normalized3 ) (0.390 m) (0.482 m) (0.421 m) A ll Sites (0.006 m ) 8 10 52 49 9 29 23 22 17 39 75 71 Dune Sand/Water-Laid Sand Sites Sand Dune Encompassed Sites Non-Sand Dune Sites aExtreme cases were elim inated by considering only those s ite s where rates are w ith in two standard deviations o f the mean ra te . ^Sand dune encompassed b lu f fs include those s ite s whose b lu f fs are composed e n t ir e ly o f dune sand and those formed o f dune sand underlain by w a te r-la id sand. 67 Table 6, Results o f Student's _t te s ts in d ic a tin g a s t a t i s t i c a l l y s ig n if ic a n t d iffe re n c e ( a t the ,05 s ig n ific a n c e le v e l) in long-term average annual b l u f f li n e recession rates along the combined Michigan and Wisconsin study areas between b lu f f s encompassing dune sand and b lu f f s composed o f non­ sand dune sediments. Sample Group Sand Dune Sites # of Cases Mean Rate Std. Dev. Var­ iance Std. Error 22 0.551' 0.824 0.679 .176 Student's t_ .000 Non-Dune Sites 75 1.639' 1.420 2.016 .164 Sand Dune Sites (normalizeda ) 22 0.551' 0.824 0.679 .176 Non-Dune Sites .000 71 1.377' 0.861 0.741 .102 17 0.824' 0.712 0.507 .173 (normalized9 ) Dune Sand/WaterLaid Sand Sites .001 Non-Dune Sites 75 1.639* 1.420 2.016 .164 Dune Sand/WaterLaid Sand Sites (normalizeda ) 17 0,824' 0.712 0.507 .173 Non-Dune Sites (normalizeda ) 71 1.377' 0.861 0.741 .102 39 0.670' 0.779 0.607 .125 Sand Dune Incompassed Sites*5 .016 .000 75 1.639' 1.420 2.016 .164 Sand Dune Encompassed Sites*5 (normalizeda ) 39 0.670' 0.779 0.607 .125 Non-Dune Sit.es (normalized ) 71 Non-Dune Sites .000 1.377' 0.861 0.741 .102 aExtreme cases were e lim in a ted by considering only those s ite s where rates are w ith in two standard d e viations o f the mean ra te . Sand dune encompassed s ite s include those s ite s whose b lu ffs are composed e n t i r e l y o f dune sand and those.formed o f dune sand underlain by w a te r- la id sand. 68 Table 7 . Results o f Student's t. te s ts in d ic a tin g a s t a t i s t i c a l l y s ig n if ic a n t d iffe re n c e (a t the ,05 s ig n ific a n c e le v e l) in long-term average annual b l u f f l in e recession rates along the Michigan study area between b lu f f s encompassing dune sand and b lu f f s composed o f non-sand dune sediments. Sample Group # of Cases Mean Rate Std. Dev. Var­ iance Std. Error Sand Dune Sites 20 0.605' 0.838 0.702 .187 Student's t .000 Non-Dune Sites 23 1.701' 0.912 0.832 .190 Sand Dune Sites (normalized3 ) 20 0.605' 0.838 0.702 .187 Non-Dune Sites (normalized3 ) 22 1.583' 0.731 0.534 .156 Dune Sand/WaterLaid Sand Sites 9 1.007’ 0.567 0.321 .189 Non-Dune Sites 23 1.701' 0.912 0.831 .190 Dune Sand/WaterLaid Sand Sites (normalized3 ) 9 1.007' 0.567 0.321 .189 Non-Dune Sites (normalized3 ) 22 1.583' 0.731 0.534 .156 29 0.729' 0.777 0.604 .144 Sand Dune . Encompassed Sites Non-Dune Sites Sand Dune . Encompassed Sites (normal ized3 ) Non-Dune Sites (normalized3 ) .000 .043 .043 .000 23 1.701' 0.912 0.832 .190 29 0.729' 0.777 0.604 .144 .000 22 1.583 0.731 0.534 .156 aExtreme cases were e lim inated by considering o n ly those s ite s where rates are w ith in two standard d e viations o f the mean ra te . Sand dune encompassed s ite s include those s ite s whose b lu f f s are composed e n t i r e l y o f dune sand and those formed o f dune sand underlain by w a te r - la id sand. 69 Table 8. Results o f Student's t te s ts in d ic a tin g a s t a t i s t i c a l l y s i g n if ic a n t d iffe re n c e ( a t the ,05 s ig n ific a n c e le v e l) in long-term average annual b l u f f l i n e recession rates along the Wisconsin study area between b lu f f s encompassing dune sand and b lu f f s composed o f non-sand dune sediments. Std. Dev. Var­ iance Std. Error 0.499' 0.801 0.642 .253 2.566 .222 0.642 .253 Sample Group # of Cases Mean Rate Sand Dune a Encompassed Sites 10 Student's t .003 Non-Dune Sites 52 1.611' 1.602 Sand Dune Encompassed S ite ^ (normalizedb ) 10 0.499' 0.801 Non-Dune Sites (normalized^) .014 49 1.284' 0.905 0.819 .129 aSand dune encompassed b l u f f s ite s include those s ite s whose b lu f f s are composed e n t i r e l y o f dune sand and those formed o f dune sand underlain by w a te r - la id sand. ^Extreme cases were e lim in a te d by considering only those s ite s where rates are w it h in two standard d e via tio n s o f the mean ra te . 70 Table 9. Results o f a Student's Jfc t e s t in d ic a tin g th a t there is s t a t i s t i c a l l y no s i g n i f ic a n t d iffe re n c e ( a t the ,05 s ig n ific a n c e le v e l) in the long-term average annual recession rates between the Wisconsin and Michigan b lu f f s encompassing dune sand ( i . e . , a l l sand dune s ite s and dune sand underlain by w a te r- la id sand b l u f f s i t e s ) . Sample Group Wisconsin Sand Dune Encompassed Sites Michigan Sand Dune Encompassed Sites # of Cases Mean Rate Std. Dev. Var­ iance Std. Error 10 0.499' 0.801 0.642 .253 Student's 1: .428 29 0.729' 0.777 0.604 .144 aBecause there are o n ly two Wisconsin sand dune s ite s the t e s t comparing these b lu f f s to M ichigan's 20 sand dune s ite s is meaningless and is th e re fo re not present. 71 Sand dune b lu f f s are probably no le s s , and may even be more, susce p tib le to r e t r e a t from wave erosion than are b lu f f s formed in non-dune m a te ria l. This is supported by f i e l d and photo evidence and testimony o f shorezone residents f o r many lo c a tio n s during the high water period since 1968. However, the g e n e ra lly lower long-term recession rates a t dune s ite s can probably be ascribed to eolian accretio n a t most o f these lo c a tio n s during lower water periods. Although t h is study has not monitored s ite s over a long time span ample evidence in d ic a te s th a t a t many o f these and o th e r places when wide sand beaches p re v a il l o w - r e l i e f dunes (foredunes) tend to form in the backshore (Figure 15; S c o tt, 1942, n . d . ; Olson, 1 958c; Davis, S eibel, and Fox, 1973; Davis, 1976). Apparently these foredunes do not develop un ifo rm ly along the shorezone and the reason fo r t h e i r uneven d is t r ib u t io n and formation is not known. In Michigan they seem to be most common along reaches where N ip is s in g and Algoma dune forms e x i s t . 13 Although varying in width and h e ig h t, dunes exceeding 150 fe e t in width and reaching heights o f 10 to 12 fe e t and more are known to form during a s in g le low water episode (Davis, S e ib e l, and Fox, 1973; S c o tt, 1942). In the Wisconsin study area dune a c cretio n is f o r the most p a rt r e s t r ic t e d to two t r a c t s , one in southern Sheboygan County and the other in the Point Beach State Park region near Two R ive rs, Manitowoc County. But the dunes a t these places do not approach the proportions they do on the Michigan la ke sid e . 12 This r e la tio n s h ip was also tested and confirmed f o r only those s ite s north o f Port Washington, Wisconsin and those north o f the Van BurenAllegan county l i n e , Michigan. This e lim in a te s the possible bias th a t may r e s u lt because the more s o u th e rly s ite s along both lakeshores are la rg e ly non-dune b lu f f s which t y p i c a l l y d is p la y high recession ra te s . 13 segments. However, they may also be found fr o n t in g non-dune shoreland 72 Figure 15. Sand dune erosion and a c cre tio n between 1968 and 1977 at s i t e M31, South Line / Section 33 / T13N,R18W, MuskegonOceana county l i n e , Michigan. (A) 1968: Foredunes, b u i l t up during the previous decade, have j u s t begun to undergo erosion by storm waves at the beginning o f the present period o f high lake le v e ls . (B) 1973: The lake has reached i t s highest le v e l since 1886. Beaches no longer e x is t and the sand dunes are being severely eroded; the s ta irc a s e in photo A has long since dissappeared. (C) J u ly , 1977: Between 1973 and 1977 the mean annual water e le v a tio n has dropped almost two f e e t , beaches have again developed, and e o lia n sand is beginning to accumulate in the backshore. (D) September, 1978: Although the lake le v e l has rise n s l i g h t l y from the year before and beaches are somewhat narrower, a c t iv e ly a c c re tin g foredunes have established themselves f r o n t in g the p re v io u s ly eroded dune b l u f f . 73 (A) 1968 (B) 1973 Figure 15 (c o n t'd . ) . (D) September, 1978 Figure 15. ( c o n f d . ). 75 The r e l a t i v e e ffe c tive n e s s o f foredunes in delaying b l u f f lin e recession once high lake le v e ls allow accelerated wave erosion to begin may be i l l u s t r a t e d . Twenty 14 Michigan dune and non-dune b l u f f s ite s which experienced long-term recession e x h ib ite d no c re s t r e tr e a t during the 1968 to 1977 high water stage. F ifte e n in 1976-77 by a foredune or by one in 1968 15 16 o f the 20 were fronted a t the beginning o f the high water period. Not a l l sand dune s ite s e x h ib it low recession ra te s ; furtherm ore, s ite s experiencing low rates are not necessarily characterized by dunes. Where co n d itio n s no longer allow adequate sand replenishment during low water periods dune s ite s can e x h ib it s u b s ta n tia l net losses. This may happen when the co n stru ctio n o f groins or j e t t i e s prevent l i t t o r a l d r i f t from reaching the dune area. I t is curious th a t the s h o re lin e o f the eastern study area appears on the whole so smooth, even though both recession rates and physiography vary s i g n i f i c a n t l y along the lakeshore. For example, data show th a t long-term recession rates a t non-dune s ite s tend to be twice as great as a t dune s i t e s , suggesting th a t s h o re line c o n fig u ra tio n should r e f l e c t these d i f f e r e n t i a l ra te s . But t h is appears not to be the case; most o f the dune areas do not protrude lakeward nor are most non-dune shoreland segments embayed. A smooth o u t lin e , however, was ^ F o u r o f the 20 are the double-crested dune s ite s M23, M31, M36, and M53. 15 The o th e r f iv e have b lu f f s whose heights equaled or exceeded 69 f e e t ; see " B l u f f Height" in the fo llo w in g s e c tio n . ^ T h i s was confirmed by examination o f 1968 Michigan Department o f Natural Resources o blique c o lo r s lid e s o f each s i t e lo c a tio n . 76 not associated w ith some o f Lake Michigan's ancestral lakes. Shorelines o f higher p ro g la c ia l la k e s , notably Lakes Algonquin (11,500 years BP) and N ip iss in g (4,000 years BP), embodied numerous embayments. Furthermore, most o f the present day sand dunes are associated w ith the ancestral embayments (S c o tt, 1942; n . d . ) . Apparently the smooth shoreline o f modern Lake Michigan is d u a lly a t t r ib u t e d to the accumulation o f sand dunes in these indentations as the ancestral lakes changed e le va tio n and to the accelerated r e tr e a t o f the non-eolian shoreland segments separating the embayments. The fa c t th a t t h is study found s i g n if ic a n t d iffe re n c e s in long-term recession rates between dune and non-dune b lu f f s suggests th a t t h is s h o re lin e only most re c e n tly a tta in e d i t s present degree o f smoothness. This smoothness, however, is r e la t iv e and i t s awareness depends to a large degree on scale. When compared h i s t o r i c a l l y , and viewed on a small s ca le , the sho re line has indeed become much less ir r e g u l a r . But on a large scale t h is smoothness is less s t r i k i n g and i t s perception may be a t t r ib u te d to the r a t i o between the distance ( in thousands o f fe e t) separating adjacent study s ite s and t h e i r recession values ( in tens and hundreds o f fe e t). This r a t i o is large enough th a t the s h o re line would appear smooth, even though there are d i f f e r e n t i a l recession rates ta k in g place. In summary, during higher lake stages low foredunes may q u ic k ly come under attack by storm waves but t h e i r presence may prevent or delay erosion on the landward shoreland. Furthermore, when the lake le ve l drops foredunes can ge n e ra lly be expected to form once again in those areas where they e x iste d p re v io u s ly , provided shorezone conditions have remained s im ila r . However, as a consequence o f the p e rio d ic nature o f these a cc re tio n a ry and erosional events, a t sand dune lo c a tio n s net 77 long-term recession rates tend to be lower but gross long-term losses may be greater than at non-dune s it e s . R elationship o f B l u f f Recession to Other Selected Variables Ground Water While ground water a c t i v i t y cannot be d i r e c t l y c o rre la te d w ith rates o f recession i t does seem to be an im portant v a ria b le in the mechanics o f b l u f f c r e s t r e tr e a t a t many s it e s . I t is important to note th a t most b l u f f recession takes place through slope f a i l u r e . While t h is may be i n i t i a t e d by wave erosion at the b l u f f toe ground water w ith in the b l u f f i t s e l f is o fte n a c r i t i c a l fa c to r c o n trib u tin g to i n s t a b i l i t y (Savage, 1968; B ird and Armstrong, 1970; Selby, 1970; Hadley, 1974, 1976; Gray, 1975; Great Lakes Basin Commission, 1977; Mickelson, e t a l . , 1977; V a lle jo , 1977; and o th e rs ). Subsurface water has several d e s ta b iliz in g e ffe c ts which may independently or in unison cause slope f a i l u r e . F i r s t , i t increases porewater pressure and decreases the cohesiveness and shear strength o f the b l u f f m a te ria l. Second, i t tends to move downward through permeable layers u n t il r e l a t i v e l y impermeable zones are encountered and some water is then d iv e rte d along t h is horizon toward the b l u f f face. The force o f the ground water discharge at the face can remove granular p a r tic le s from the permeable bed and thus e v e n tu a lly remove support f o r o v e rly in g sediments. And, t h i r d , la rg e q u a n titie s o f ground water can cause high shear stre ss w it h in the slopes because i t increases the u n it weight o f the b l u f f m a t e r ia l. Perched water co n d itio n s are la r g e ly confined to b lu f f s composed o f m u ltip le sediment layers o f d i f f e r e n t p e rm e a b ilitie s ; they are r a re ly 78 found in dune b l u f f s . F i f t y - e i g h t percent o f the Wisconsin b l u f f p r o f ile s include both permeable and r e l a t i v e l y impermeable s t r a t a ; t h is circum­ stance e x is ts at only 34% o f the Michigan lo c a tio n s . Furthermore, ground water was detected discharging from the b l u f f face at twice as many s ite s in Wisconsin as in Michigan. These fa c ts and oth e r observations suggest t h a t , on the whole, ground water seepage is probably more detrimental to the maintenance o f b l u f f slope s t a b i l i t y along the Wisconsin lakeshore than along the Michigan shore. The b l u f f segment encompassing s ite s W18-W24 in southern Ozaukee County, Wisconsin i l l u s t r a t e s the aforementioned c o n d itio n . t h is t r a c t are very large slump blo cks, u su a lly s t i l l a t the base o f the b l u f f ' 7 (Figure 6 ). Throughout vegetated, re s tin g Ground water discharge is evident a t most lo c a tio n s and i t is not uncommon f o r i t to pond on the upper surface o f the slump block. Even though the blocks p ro te c t the b l u f f from f u r t h e r erosion many o f the b l u f f crests appear to be s t i l l a c tiv e ly r e tr e a tin g due to slope f a ilu r e above the le ve l o f the slump blocks. It is h ig h ly l i k e l y th a t i n s t a b i l i t y caused by ground water seepage contributes s i g n i f i c a n t l y to the high long-term b l u f f recession rates recorded in th is lo c a t io n . Ground water performs an im portant fu n c tio n in b l u f f slope evo lu tio n in o th e r areas along the Wisconsin lakeshore (E d il and V a lle jo , 1977; V a lle jo , 1977; Mickelson, e t a l . , 1977). demonstrated th a t a section o f t i l l For in sta n ce , Whitney (1936) b lu f f s north o f Milwaukee f a ile d p r im a r ily because o f ground water a c t i v i t y . And Hadley (1974) states th a t i t c o n trib u te s s i g n i f i c a n t l y to the slumping and high b l u f f l i n e recession along Bender Park in southern Milwaukee County ( s i t e W13). 17In 1918 Alden reported th a t t h is shorezone segment in Ozaukee County was experiencing "much slumping down o f the b l u f f in places" (p. 338). 79 B l u f f Height Even though banks o f increasing heights provide a greater p o te n tia l volume o f sediments data show th a t long-term recession rates appear not to be re la te d d i r e c t l y to b l u f f h e ig h t. On a sh o rt-te rm b a sis, however, high banks may show fa r le s s , or more, c re s t recession than low b l u f f s . Because the h o rizo n ta l distance between base and c re s t is greater f o r high than low b lu f f s a longer time may be needed f o r i n i t i a t i o n o f c re s t r e tr e a t on the higher banks once accelerated erosion begins. This s it u a tio n is e s p e c ia lly apparent on b lu ff s whose p r o f ile s contain th ic k sequences o f more cohesive sediments. For example, o f the e ig h t Michigan s ite s w ith b lu f f s over 100 f e e t , f iv e displayed no recent c re s t recession even though t h e i r long-term losses ranged from 0.80 to 2.92 fe e t (0.244 to 0.890 m) annually. Although one was p reviou sly protected by a foredune the remaining fo u r were n o t. Each o f these b lu f f s had experienced appreciable toe erosion r e s u ltin g in an over­ steepened slope. But the c re s t lin e area o f each had not receded, apparently because the upper slope material was cohesive enough to remain standing a t a high angle. a s in g le high water period. This co n d itio n might po ssib ly l a s t longer than When the upper slope does f a i l , however, c re s t r e tr e a t may be r e l a t i v e l y g re a t; in a s in g le event the b l u f f lin e could recede as much as a low b l u f f c re s t did over a f iv e or ten year period. In oth e r cases, when lake le v e ls drop and wave erosion dim inishes, high b l u f f slopes may be expected to e s ta b lis h e q u ilib riu m p r o f ile s less r a p id ly than low b l u f f faces because the higher crests must recede a g re a te r distance fo r slopes to become s ta b le . Therefore, i t would not be unusual f o r mass-movement, accompanied by subsequent c re s t r e t r e a t , to continue on the higher b l u f f slopes f o r some time a f t e r i t had h alted on the low b l u f f s . 80 The lack o f c o r r e la tio n found between heights and long-term recession rates on non-dune b lu f f s may also be a t t r ib u t e d , in p a rt, to ground water. In non-dune areas the higher the b l u f f the more l i k e l y i t s s tra tig ra p h y is composed o f both permeable and r e la t i v e l y impermeable sediments, r e s u ltin g in a higher p r o b a b ilit y f o r perched water ta b le s . In t h is study ground water seeps were detected in most b lu f fs more than 50 fe e t in h e ig h t. In summary, f o r slopes o f high b lu f f s to reach stable angles once accelerated wave erosion ceases, t h e i r c re s t lin e s must r e tr e a t longer distances over greater time than those o f low banks. Thus, crests o f high b lu f f s w i l l most l i k e l y r e tr e a t g rea te r distances in a s in g le event than do crests o f low b l u f f s . As a r e s u lt there may be very l i t t l e d iffe re n c e in the long-term recession between high and low b l u f f c re s ts . Shorezone P rote ctio n Structures Although not demonstrated q u a n t it a t i v e ly , f i e l d observations f o r t h is study support conclusions reached by o th e r in v e s tig a to rs (Larsen, 1972; Davis, S e ib e l, and Fox, 1973; U.S. Army Corps o f Engineers, 1973, 1974; Omohundro, 1973; League o f Women Voters, 1974; Hadley, 1976) t h a t shorezone p ro te c tio n devices commonly cause undesirable aberrations in beach, b l u f f , and/or nearshore c o n d itio n s . Measuring, and even re c og n izin g , the f u l l impact th a t these s tru c tu re s have on the lakeshore is d i f f i c u l t , but observations show th a t many o f these devices prompt abnormally high erosion and/or accretio n in areas adjacent to them. The p ro te c tio n s tru c tu re s most commonly erected along the shorezone may be d ivided in to two groups--groins and j e t t i e s , and seawalls and revetments. Because groins and j e t t i e s tend to extend perp e n d icu la rly from the sh o re lin e they r e s t r i c t passage o f l i t t o r a l d r i f t . Beaches thus 81 tend to widen on t h e i r u p d r if t side through trap p in g but narrow on the do w n d rift side o f the s tru c tu re because the supply o f sediments is reduced or e lim in a te d . With time beaches in these do w n d rift areas u su a lly become in c re a s in g ly meager and may be unable to adequately p ro te c t the shoreland from storm waves, possibly r e s u ltin g in accelerated b l u f f recession. This c o n d itio n is known to e x is t a t s ite s Ml, M2, and M8 where high b l u f f re tre a ts are p a r t i a l l y a t t r ib u t e d to the adverse e ffe c ts o f harbor j e t t i e s (U.S. Army Corps o f Engineers, 1973; 1974). Seawalls and revetments are g e nerally located p a r a lle l to the base o f shoreland b lu f f s to p ro te c t them against erosion by incoming waves. U n fo rtu n a te ly , the scouring e f f e c t o f the breaking waves normally re s u lts in deeper water conditions lakeward o f the s tru c tu re s . As a consequence even when r e l a t i v e l y wide beaches form nearby they seldom develop in f r o n t o f seawalls and revetments. More im p o rta n tly , because adjacent unprotected b lu f f s may recede at greater ra te s , the armored tr a c ts commonly become promontories. Without p e rio d ic re p a ir and extension, however, the s tru ctu re s are eve n tu ally flanked by storm waves and t h e i r e ffe c tive n e s s destroyed. Shoreline O rie n ta tio n Shoreline trends a t the study s ite s vary by almost 100 degrees (see Appendix B, Tables B1 and B2). In Wisconsin they range between N48°W and N48^°E whereas in Michigan they vary from N30°W to N38° e J 8 18 Shoreline o r ie n ta tio n is based on lakeshore segments extending a q u a rte r m ile to each side o f the s i t e . S t a t i s t i c a l analysis in t h is section is based on data fo r only those lo c a tio n s where sh o re line trend is s im ila r on both sides o f the s i t e ; t h is c r i t e r i o n e lim in a te s a few s ite s where shorelines have a concave or convex c o n fig u ra tio n but t h e i r exclusion does not a f f e c t the conclusions reached. 82 Michigan s ite s were separated in to two ca te g o rie s , one w ith shoreline trends in the northwest quadrant and the o th e r w ith o rie n ta tio n s toward the northeast. The average y e a rly r e tr e a t value f o r northw esterly o rie nte d s ite s is 0.88 fe e t w h ile the ra te f o r n o rth e a s te rly tren d in g lo ca tio n s is 1.51 fe e t. 19 Student's t_ te s ts in d ic a te th a t average b l u f f loss between these two groups is s t a t i s t i c a l l y d i f f e r e n t . 20 Examination o f Wisconsin data reveals a tendency f o r recession rates to d i f f e r when s ite s are separated based on a N10°E trend l i n e . The mean r e tr e a t rate f o r lo ca tio n s where the o r ie n ta tio n is westward o f N10°E is 2.15 fe e t y e a r l y . ^ For those s ite s whose trend is eastward o f N10°E, the average rate is only 0.90 f e e t. Student's t analysis establishes th a t the rates between the two groups are s i g n i f i c a n t l y d i f f e r e n t . 22 The Michigan and Wisconsin trend categories w ith the higher r e tr e a t rates correspond to s ite s l i k e l y to experience more d ir e c t exposure to high energy storm waves. In Wisconsin the most damaging winds are g e nerally from the northeast quadrant (Hadley, 1976; Mickelson, e t a l . , 1977) and on the Michigan lakeshore north w e ste rly storm winds are commonly the most d e s tru c tiv e and longest la s t in g (Jay Harman, personal communication). However, the r e la t i v e importance o f these o rie n ta tio n s is rendered less 19 I f on ly s ite s whose rates are w ith in two standard the mean are considered, the rate is 1.39 fe e t annually. deviations o f 20 Student's t is 0.026; i f only s ite s whose rates are w ith in two standard deviations o f the mean are considered, Student's t_ is 0.046. The le v e l o f s ig n ific a n c e was e stablished as 0.05. 21 I f only s ite s whose rates are w ith in two standard deviations o f the mean are considered, the ra te is then only 1.55 fe e t annually. 22 Student's t i s 0.005; i f on ly s ite s standard deviations are considered, Student's s ig n ific a n c e was esta b lish e d as 0.05. whose rates are w ith in two t is 0.018. The le ve l o f 83 c le a r by the fa c t th a t the m a jo rity o f the n orthw esterly tre n d in g s ite s in Wisconsin and the n o rth e a s te rly o rie n te d s ite s in Michigan are located in the southern p o rtio n o f the lake basin. The r e l a t i v e l y large fetches over which the major storm winds can tra v e l and waves develop may be as much, or more, i n f l u e n t i a l f o r accelerated b l u f f recession than the o r ie n ta tio n o f the s h o re lin e . Beach Width Beach cond itio n s are in fluenced by lake le v e l , sediment sources, l i t t o r a l c u rre n ts , weather c o n d itio n s , shorezone s tru c tu r e s , and nearshore slopes. Changes in any one o f these may s u b s t a n tia lly a l t e r beach c h a r a c te r is tic s and th e re fo re i t s a b i l i t y to p ro te c t lakeshore b lu f f s against storm wave e rosion. Although d ir e c t re la tio n s h ip s between beach widths and long-term b l u f f recession rates are not e s ta b lish e d in t h is study, many f i e l d obse rva tio n s, as exe m p lified by Figure 16, c le a r ly i l l u s t r a t e the im portant fu n c tio n performed by the beach. Im p lic a tio n o f Other Factors I t is obvious th a t the land o rie n te d varia bles considered in t h is study are adequate to account f o r much o f the s p a tia l v a r ia tio n in shoreland recession, and even when recognized t h e i r r e la t iv e importance is questionable. Success in understanding the causal fa c to rs in b l u f f erosion is probably b e tte r met i f the in v e s tig a tio n is extended in t o the near- and o ffs h o re environments. I t seems l i k e l y th a t p o in t - t o - p o in t v a ria tio n s in b l u f f r e t r e a t are lin k e d to d iffe re n c e s in wave energy d is t r ib u t io n along the shore and to such fa c to rs as lo c a liz e d eddies and c u rre n ts , nearshore sand bars, reefs and bottom i r r e g u l a r i t i e s , and l i t t o r a l d r i f t . 84 (A) Ju ly 4, 1973 Figure 16. V a ria tio n in beach widths a t the South Line / Section 15 / T12N,R18W, Muskegon County, Michigan, 1973-1977. In J u ly , 1973 (photo A) Lake Michigan's monthly le v e l averaged 580.98 fe e t . No beach e xisted and the b l u f f was very susce p tib le to storm wave erosion. By September, 1976 (photo B; average monthly water l e v e l :579.92 fe e t) and co n tinuing through J u ly , 1977 (photo C; mean monthly lake e le v a tio n : 578.57 f e e t ) the lake surface had dropped (although remaining above average) and p ro te c tin g beaches had formed. 85 (B) September 30, 1976 (C) Ju ly 3, 1977 Figure 16 ( c o n t 'd . ) - 86 Other in v e s tig a to rs have reached s im ila r conclusions. Davis (1976), Davis, S e ib e l, and Fox (1973), Fox and Davis (1973), and Saylor and Hands (1970) suggest th a t beach and b l u f f changes are re la te d to the in te r a c tio n o f incoming storm waves and the nearshore sand bar system. Gelinas and Quigley (1973) re p o rt th a t the t o t a l wave energy reaching a p o rtio n o f the Lake Erie s h o re line c o rre la te s well w ith long-term average rates o f e rosion. And f o r a th re e -k ilo m e te r reach in southwestern Michigan Maresca (1975, pp. 145 and 158) demonstrates th a t t o t a l b l u f f li n e recession and beach erosion are dependent upon the complex in t e r a c t io n o f the t o t a l energy d is t r ib u t e d along the s h o re lin e and the r e s u ltin g tra n s p o rt o f sediments o ffsh o re and alongside and th a t the d is t r ib u t io n o f wave energy along the sh o re line depends on the convergence and divergence o f wave energy due to wave r e f r a c t io n , the unequal d is s ip a tio n o f the wave energy before the wave breaks on the shore, and the balance or imbalance o f the alongshore tra n s p o rt o f m a te r ia l. Furthermore, in a recent re p o rt on b l u f f recession in Racine County, Wisconsin K e i l l o r and DeGroot (1978, p. 3) s ta te th a t ir r e g u la r bottom fe a tu re s , bars and reefs modify the path th a t waves take towards shore. These natural underwater landforms can cause wave energy to concentrate, or spread out and d is s ip a te on local beaches. The patterns vary depending on d ir e c tio n o f approaching waves and on wave c o n d itio n s .23 23 K e il lo r and DeGroot had constructed wave r e fr a c t io n diagrams f o r dominant NNE storm waves and found th a t wave energy is more dispersed along the shore south o f Wind Point than to the n o rth . The Point and nearby submerged reefs p a r t i a l l y protected the southern reach from the f u l l impact o f the storm waves. The less protected northern segment correspondingly experienced g re a te r b l u f f recession than to the south. The r e la t i v e d iffe re n c e in recession rates between these two shorezone segments is i l l u s t r a t e d by the rates determined f o r s ite s W8-W13 in t h is study. 87 The r e la tio n s h ip between b l u f f recession rates and nearshore bathymetry and wave and c u rre n t a c t i v i t y is complex. Data are not r e a d ily a v a ila b le and success in e s ta b lis h in g the s ig n ific a n c e o f the c o r r e la tio n on a lakewide basis awaits f u r th e r in v e s tig a tio n . Assessment o f Factors In flu e n c in g Large-Scale Patterns in B l u f f Recession Rates______ Several e s p e c ia lly im portant fin d in g s o f t h is study deserve assessment: f i r s t , the unexpected s i m i l a r i t y in o v e ra ll long-term b l u f f li n e recession rates between the Michigan and Wisconsin shorelands; second, the tendency f o r s ite s in the southern portio n o f each study area to e x h ib it above average b l u f f losses; and t h i r d , the s i g n i f i c a n t l y lower recession rates along Wisconsin's northern as compared to southern 1akeshore. Both study areas p e r io d ic a lly experience severe storm winds and waves, although t o t a l y e a rly energy from incoming deep water storm waves is greater on the Michigan lakeside ( S a v ille , T953; Davis and Fox, 1974). Apparently, however, the b e tte r development o f longshore sand bars (Hands, 1970; 1976) and beaches (Krumbein, 1950; Hulsey, 1962) on the eastern margin lessens incoming shallow water wave energy and may reduce p o te n tia l long-term b l u f f recession ra te s . Furthermore, because o f many more dune s ite s on the eastern la k e s id e , Michigan's mean recession ra te r e fl e c t s more s tro n g ly the in flu e n ce o f foredune regeneration and consequently is a lower value than would be expected had not foredunes i n t e r m it t e n t ly formed. Moreover, on the Wisconsin shorezone a higher incidence o f co n ditions detrim ental to b l u f f slope s t a b i l i t y 24 24 seems to These conditions are caused more notably by ground water w ith in b lu f f s o f m u ltip le sediment layers o f d if f e r e n t p e rm e a b ilitie s . 88 p r e v a il, a s itu a tio n t h a t would tend to am plify r e tr e a t rates on Wisconsin's shoreland. This combination o f fa cto rs may well r e s u lt in s im ila r o v e ra ll average annual b l u f f recession rates f o r the two lakeshores. The higher r e tr e a t rates experienced by s ite s along the southern p o rtio n o f each s ta te are l i k e l y due to a combination o f several fa c to rs : the dominant storm winds a f f e c t in g Lake Michigan, the large fetches over which they t r a v e l, and sho re line trends which tend to be more normal than p a r a lle l to the p r e v a ilin g storm waves. Because wave size is d i r e c t l y re la te d to wind v e lo c it y , wind d u ra tio n , and fe tc h , storm wave development, and th e re fo re wave energy and p o te n tia l erosional a b i l i t y , is l i k e l y to be greatest along these reaches. In a d d itio n to d iffe re n ce s in dominant storm winds, in Wisconsin several o th e r fa c to rs may in flu e n c e the s i g n i f i c a n t l y lower average recession rates found a t most s ite s north o f Port Washington; the r e la t i v e importance o f each o f these varia bles is unknown, however. For one, the o v e ra ll s h o re lin e trend north o f Port Washington approaches n o rth -n o rth e a s t, which places i t more p a r a lle l than normal to the dominant n o rth e a s te rly storm winds and waves. 25 Southeasterly winds would p o t e n t i a l l y be more damaging but storm winds from th a t d ir e c tio n 25 The major exception to t h is n o rth -n o rth e a s te rly trend is the northern headland p o rtio n o f Point Beach State Forest, Manitowoc County, where the sh o re line is o rie n te d no rth -n o rth w e st. The beach ridges th a t form the headland have been severely eroded here; Gorder (1975) estimated an average loss o f about three fe e t per year during the l a s t 3,000 years. In the present in v e s tig a tio n the two northern study s ite s w ith the highest recession rates (W52, 2.63 fe e t/y e a r ; W53, 1.77 fe e t/y e a r) are located in the v i c i n i t y . The n o rth e a s te rly tre n d in g southern p o rtio n o f the headland appears to be protected by beaches whose sands have come by way o f longshore currants from the eroded beach ridges in the northern p a rt o f the headland (Pauli and P a u li, 1977). 89 are uncommon. Secondly, nearshore bedrock reefs are known to e x is t in places along the northern reach, as are longshore sand bars; both features may reduce incoming wave energy and re ta rd b l u f f losses. T h ir d ly , f o r extended lengths north o f Sheboygan nearshore bottom slopes appear to be more gentle than are slopes south o f Sheboygan to Milwaukee. And l a s t l y , along t h is northern shore are found the two Wisconsin sand dune t r a c t s . The low long-term recession rates in these dune reaches are s t a t i s t i c a l l y s im ila r to those in dune areas on the Michigan side o f the la ke . In c o n tra s t, s ig n i f i c a n t d iffe re n ce s in recession rates between s ite s in the northern and southern portions o f Michigan are not l i k e l y . Not only are northern and southern shorezone c h a r a c te r is tic s more s im ila r than on the Wisconsin side but the Michigan 1akeshore is influenced by strong storm winds and waves from both the southwest and northwest quadrants (although t o t a l y e a rly wave energy is r e l a t i v e l y g re a te r from the northwest quadrant). Summary The fo llo w in g summary statements are based on s i t e data and re la te d observations. (1) S ite data in d ic a te th a t o ve ra ll long-term b l u f f recession along the Wisconsin and Michigan shorezones is s t a t i s t i c a l l y s im ila r . (2) Non-sand dune s ite s along the southern p o rtio n o f both lakeshores tend to be experiencing r e l a t i v e l y ra pid long-term r e tr e a t . (3) Wisconsin b lu f f s a t s ite s south o f Port Washington (Ozaukee County) are receding a t rates s i g n i f i c a n t l y higher than those a t study lo c a tio n s north o f the c i t y . 90 (4) On the whole, sand dune b lu f f s are receding a t s i g n i f i c a n t l y lower rates than are b lu f f s composed o f non-dune sediments. These generally lower long-term values can probably be a t tr ib u t e d to dune accretion at most o f these lo ca tio n s during lower lake stages. (5) Long-term b l u f f recession rates cannot be c o rre la te d w ith s p e c ific sediments or sediment arrangements f o r those s ite s whose b lu f f s are composed o f non-eolian m a te ria l. (6) Data on ground water a c t i v i t y and b l u f f height cannot be d i r e c t l y re la te d to varying rates o f long-term recession. However, ground water seepage appears to be an im portant c o n trib u to r to b l u f f slope i n s t a b i l i t y , and because i t is p revalent in most high non-dune b l u f f s , i t may a t le a s t p a r t i a l l y account f o r the lack o f c o r re la tio n between r e tr e a t values and b l u f f he ig h ts. (7) Shoreline o r ie n t a t io n , coupled w ith fe tc h , appears to in flu e n ce rates o f b l u f f recession. (8) Beach widths cannot be m eaningfully re la te d to long-term r e tr e a t values. (9) I t is apparent th a t lakeside p ro te c tio n s tru c tu re s in t e r f e r e w ith natural shorezone processes. Although t h e i r e f f e c t may be lo c a lly b e n e f ic ia l, they commonly i n i t i a t e adverse conditions elsewhere, e s p e c ia lly in adjacent and/or d o w n d rift lo c a tio n s . Chapter 4 MODERN RATES OF BLUFF RECESSION AND THEIR FUTURE IMPLICATIONS: TWO CASE STUDIES In tro d u c tio n In the context o f two case study areas the o b je c tive s o f t h is chapter are: (1) to determine b l u f f losses during approximately the l a s t fo u r decades, (2) to i l l u s t r a t e the e ffe c ts shorezone p ro te c tio n s tru c tu re s can have on b l u f f r e tr e a t and lakeshore c o n d itio n s , and (3) to discuss and p re d ic t fu tu re b l u f f p o s itio n s and t h e i r consequences. The f i r s t case study segment consists o f the 1.4 mile long lakeshore o f the V illa g e o f Shoreham, Berrien County, Michigan. The second area encompasses the Lake Michigan shorezone in the northern two sections o f Kenosha County, Wisconsin (Figure 4 ). because: These l o c a l i t i e s were chosen (1) based on section lin e s i t e s , they represent shorelands experiencing above average long-term b l u f f recession; (2) numerous r e s id e n tia l and commercial stru ctu re s have been destroyed and many are threatened by b l u f f e ro sio n ; (3) b l u f f lin e s are g enerally w e ll- d e fin e d ; and (4) r e l a t i v e l y good q u a lit y ste re o -p a ire d a e ria l photos are a v a ila b le f o r several years since 1938 from which recession rates can be determined. Determination o f Recession Rates Modern recession values were determined photogrammetrically by comparing b l u f f lin e p o s itio n s on o ld e r panchromatic s te re o -p a ire d a e ria l photography w ith p o s itio n s on more recent imagery. The photos were p re c is e ly scaled by f i e l d measurements o f features found both on 91 92 the ground and on the a e ria l imagery. Retreat rates are ascertained f o r the fo llo w in g periods: Shoreham, Michigan N. Kenosha County, Wisconsin 1938 to 1977 1941 to 1975 1938 to 1967 1941 to 1969 1957 to 1977 1969 to 1975 The 1975 and 1977 photos represent a v a ila b le recent imagery whereas those o f 1938 and 1941 are among the e a r l ie s t taken o f the study areas. The 1967 and 1969 photos are those a v a ila b le w ith dates nearest the beginning o f the present high lake stage. Imagery covering o th e r years were also examined in order to study v is u a lly the sequential development o f the b l u f f zoneJ Table 10 l i s t s the photographs used. At 15 places in Shoreham and 22 in Kenosha County id e n tic a l features near the b l u f f edge were recognized on both the 1967 and 1977 o r 1969 and 1975 photos ( r e s p e c tiv e ly ) . For each o f the two years distances trending east-west from these landmarks to the b l u f f cre st were measured using e it h e r a 7X Alan Gordon Pocket Comparator w ith u n it increments o f 0.1 mm o r a 12-inch Gurley Rapid Comparator w ith d iv is io n a l u n its o f 0.005 inches. The d iffe r e n c e , converted to ground distance in f e e t , between the two measurements in d ica te d b l u f f l in e losses between the two dates. The margin o f e r r o r is c a lc u la te d to be w ith in 3.5 fe e t. Because few features id e n tic a l to both 1966 and 1938 or 1975 and 1941 photos are recognizable, a Bausch and Lomb Zoom Transfer Scope (ZTS) was u t i l i z e d to a sce rta in recession rates between these years. ^Recession rates were not e stablished based on these photos. Because o f t h e i r small scale and the r e l a t i v e l y few years between each photo s e t , any determined recession ra te could have been less than the margin o f e r r o r in h e re n t in the measurement technique. 93 Table 10. A e ria l photos u t i l i z e d fo r the Shoreham, Michigan, and northern Kenosha County, Wisconsin, case study in v e s tig a tio n s . Date Source3 Nominal Scale Photos Used For Measurements 4/27/77 9/11/67 6/ 5/38 MDSHT ASCS NARS 1 :12,000 1 :20,000 1:20,000 FEG-5 to 7, 15 to 17 AIT-4HH-2 to 5 AIT-4-31 to 34 Other Photos Examined 9/25/74 5/31/60 7/24/55 8/ 5/50 ASCS ASCS ASCS ASCS 1:40,000 1 :20,000 1 :20,000 1 :20,000 26021 174-238 to 240 AIT-3AA-126 to 128 AIT-5P-14 to 16 AIT-5G-110 to 113 Photos Used For Measurements 5/27/75 8/28/69 10/28/41 WDNR ASCS NARS 1 :12,000 1 :20,000 1 :20,000 BW28-36 to 39 XC-1KK-49 to 53 XD-2B-62 to 65 Other Photos Examined 6/24/63 8/14/56 9/ 6/50 8/12/37 ASCS ASCS ASCS NARS 1 :20,000 1:20,000 1:20,000 1 :20,000 Imagery Code and Frame Numbers Shoreham, Michiqan N. Kenosha Co., Wisconsin XD-1DD-42 XD-1R-30 XC-1G-24 XD-25-2296 to to to to 45 33 27 2298 aMDSHT - Michigan Department o f State Highways and Transportation ASCS - A g r ic u ltu r a l S t a b iliz a t io n and Conservation Service, United State Department o f A g ric u ltu re NARS - National Archives and Record Service WDNR - Wisconsin Department o f National Resources 94 By using the ZTS the o ld e r photos were superimposed on the la rg e r-s c a le d recent imagery. Then a t the aforementioned 15 and 22 s ite s b l u f f recession was determined by measuring the d iffe re n c e between c re s t p o s itio n s f o r the d i f f e r e n t years w ith a P ic k e tt Pocket Rule scaled in 0.01 inch increments. possib le . An estimated e r r o r o f less than 10 fe e t is I t was then a simple m atter to c a lc u la te recession values f o r the periods 1938 to 1967 and 1941 to 1969. The Shoreham Case Study Characteri s t i cs Evidenced by recent losses exceeding 100 fe e t in places, houses to p p lin g in to the la k e , and numerous shore p ro te c tio n devices, Shoreham is undergoing e s p e c ia lly severe b l u f f recession (Figure 17). F i f t y to 60 fe e t in h e ig h t, the b lu f f s are composed o f v a ria b le w a te r- la id sediments in c lu d in g loamy sand, sandy loam, and s i l t y loam; ground water seeps occur a t the top o f some o f the f i n e r sediment zones. Overall sh o re line o r ie n ta tio n is about N26°E; t h is trend may c o n trib u te to accelerated erosion as approximately twice as much y e a rly energy is derived from waves from the south-southwest through west (U.S. Army Corps o f Engineers, 1973b). B l u f f recession a t Shoreham has been accelerated by e ffe c ts o f the Federal harbor j e t t i e s three miles north o f the area a t the mouth o f the St. Joseph River (U.S. Army Corps o f Engineers, 1973; Linney, 1976). These two s tru c tu re s in t e r r u p t the southward l i t t o r a l movement 2 and lessen sand nourishment to beaches d o w n d rift. Constructed, 2 L i t t l e o r no beach b u ild in g m aterial prese n tly passes n a tu r a lly across the harbor entrance to the do w n d rift shore (U.S. Army Corps o f Engineers, 1958). 95 m 4*4 *••' — v H t k ?K r i® - ' 5 - « * •%- | € * - k T """'■&., % 1 /■ % ■ j ,J > ,1s*^& 1_i»1 \''jsfeS>, , ' ,, 1 ■‘ 'K„.. T> ‘‘V *‘ % - a ,^ ..x 1 "..W - '8 , *•*•> *> 7 £ft’ tv »4 . > < •S. w filial &" 4* v ^Vi- ^ S8 (A) A p r il 24, 1969 (B) March 27, 1973 Figure 17. Loss o f homes due to accelerated b l u f f recession, 1969 to 1978. This lo c a tio n is in the South h / Section 4 / T5S,R19W, Shoreham, Berrien County, Michigan. Between September, 1967, and A p r i l , 1977, the b l u f f a t s i t e S8 receded 166.5 f e e t ( 1 7 .2 9 '/ y r ; 50.75 m o r 5.27 m /y r). Long-term (1829-1977) r e t r e a t a t s i t e Ml is 278.13 fe e t ( 1 . 8 8 ' / y r ; 84.77 m o r 0.573 m /yr) and recent losses f o r fo u r years (1973-1977) amount to 55.13 fe e t (1 3 .7 8 '/ y r ; 16.8 m o r 4.2 m /y r ) ; see Table 14. 96 (C) A p r il o r May, 1975 (D) August 29, 1978 Figure 17 ( c o n t 'd . ) . 97 reconstructed, and repaired by segments since the 1930's, the j e t t i e s 3 reached t h e i r present lengths in 1903. P rio r to the 1830's most o f the shorezone f o r several miles south o f the St. Joseph River was apparently in a s ta te o f near e q u ilib riu m (H erbert, 1974). And u n t il the f i r s t high water period (1916 to 1920) fo llo w in g the 1903 completion o f the j e t t i e s the Shoreham b lu f f s experienced very l i t t l e re tre a t. A Corps o f Engineers' re p o rt (1958) reveals no recession a t one s it e and 4 a 23 fo o t loss a t another between 1830 and 1872. From an unpublished re p o r t, W illiam J. Gibbs, J r . , o f Shoreham w r ite s : Being f a m i l i a r , as a boy in 1916, w ith the beach and b l u f f along Lake Michigan from the harbor a t St. Joseph, south to the south end o f the Grand Mere area (10 to 12 m ile s ) , and having seen the lush growth and high trees on top o f , and on the b l u f f [ s lo p e ] , and the several old wagon t r a i l s down the b l u f f to the beach--these t r a i l s lin e d w ith 75 to 100 fo o t high white p in e s -- I am convinced th a t there had been no serious erosion o f the b l u f f in t h is area fo r many years p r io r to 1916, and as fa r back as 1872. Before 1903, but subsequent to the 1830's, some sand was probably bypassing the j e t t i e s and reaching d o w n d rift beaches. But in 1903 a c r i t i c a l length may have been reached w ith the f in a l extension whereby the s tru c tu re s cu t completely across the l i t t o r a l zone and e s s e n t ia lly blocked a l l sand movement to the south. B l u f f erosion was not an immediate problem because lake le v e ls were low and beaches wide. However, w ith the onset o f high water e le va tio n s in 1916 b l u f f recession Following the 1903 a d d itio n s o f 1,002 (n o rth ) and 1,802 (south) f e e t , the j e t t i e s reached t h e i r present lengths o f 3,152 (n o rth ) and 3,931 (south) fe e t. ^The survey l i n e f o r t h is measurement was not taken perpendicular to the b l u f f c re s t but was run along a north-south section l in e in te rs e c tin g the c re s t a t an acute angle; consequently, actual r e tr e a t would be less than t h i s 23 fe e t. 98 became a concern a t some lo c a tio n s south o f the j e t t i e s . Sites closer to these harbor s tru c tu re s were f i r s t to experience appreciable losses. In 1917 the C ity o f St. Joseph found i t necessary to i n s t a l l p ro te c tiv e devices to preserve i t s water intake and pumping f a c i l i t i e s . Although erosion apparently occurred along the Shoreham b l u f f s , accelerated r e tr e a t appeared lim it e d to the St. Joseph shoreland during t h is period. But during a l l subsequent high water episodes the Shoreham b lu f f s experienced s ig n if ic a n t recession. B lu f f Recession: 1938 to 1977 The 15 Shoreham s ite s analyzed in d e ta il are shown in Figure 18 and t h e i r recession rates are li s t e d in Table 11. For 12 o f the 15 lo c a tio n s recent (1967 to 1977) mean y e a rly r e t r e a t values are higher than f o r the periods 1938 to 1967 and 1938 to 1977. But two places (S12 and S13) underwent lower average rates between 1967 and 1977 than during the other time spans, whereas on ly one s it e ( SI4) displayed no b l u f f recession between 1938 and 1977. Furthermore, mean annual recession values f o r 12 o f 15 points were lower between 1938 and 1967 than between 1938 and 1977. The marked d iffe re n c e in average annual r e tr e a t rates fo r the three time in te rv a ls i l l u s t r a t e s the importance o f "period o f record" w ith regard to recession ra te data. Generally higher recession values are recorded f o r periods co n ta in in g g re a te r percentages o f years when water le v e ls are above normal. Between 1967 and 1977 Lake Michigan was above i t s modern long-term (1900-1977) mean annual e le v a tio n j u s t over 80% o f the tim e, and y e a rly r e tr e a t values f o r the 15 s ite s averaged a r e l a t i v e l y high 6.80 fe e t (2.073 m). However, when ca lculated f o r the period 1938 to 1967, the same s ite s l o s t an average o f 1.72 fe e t 99 / June 5, 1938, B luff Line / / A p ril 27, 1977, B luff Line : Predicted Bluff Line in 2 0 7 7 fc P s> : M IC H IG A N o rH 2 8 V - S i l t y Clay w ith s i l t & s i l t loam zones in lower p a rt P r o file 4 ____________ i 4 V - Sand w ith pebbles in lower part S i l t y Clay 8 ' - S i l t y Clay 6 V - Covered 12k'- Covered 4' - S i l t y Clay 4' - Clay Loam w ith pebbles & cobbles (T ill) 5' - Clay Loam w ith pebbles & cobbles (T ill) P r o file 1 P r o file 1 8 ' - Complex Lacustrine Sequence; interbedded zones o f sand, s i l t y loam, loam, & sandy loam 22' - Clay Loam w ith pebbles & cobbles ( T ill) 115 B l u f f Recession: 1941 to 1975 For s ix years (1969 to 1975) w ith in the present period o f high lake le v e ls 15 o f 22 Kenosha County s ite s experienced higher average annual recession rates than they did between e it h e r 1941 and 1969 or 1941 and 1975; mean r e tr e a t a t two lo c a tio n s was less (Figure 24 and Table 14). since 1941. B l u f f lin e s a t the other f iv e points have remained stable In a d d itio n , 15 s ite s sustained lower average annual r e tr e a t between 1941 and 1969 than during the time 1941 to 1975. As a whole, the study area's mean recession ra te f o r each o f the three periods i s : 1969 to 1975 2.11 fe e t/y e a r (0.643 m/yr) 1941 to 1969 0.34 fe e t/y e a r (0.256 m/yr) 1941 to 1975 1.04 fe e t/y e a r (0.317 m/yr) Although o v e ra ll r e tr e a t rates are notably le s s , the p attern o f these rates w ith respect to the three periods o f record is s im ila r to t h a t o f the Shoreham lakeside (Tables 11 and 14). The values d i f f e r depending on the period measured and the proportion o f years w ith in each time span when water le v e ls are above average. The mean annual lake e le va tio n was above the average each year between 1969 and 1975, and annual b l u f f lin e losses were the g rea te st during t h is period. Of the three in t e r v a ls , average annual losses were le a s t between 1941 and 1969, the period corresponding to the lowest percentage o f years w ith high lake le v e ls . W ithin each time in te rv a l b lu f f s a t in d iv id u a l s ite s receded a t varying ra te s , and g e n e ra lly those in the southern section less r a p id ly than those to the n o rth . Based on visual examination o f v e r tic a l and oblique a e ria l photographs the p o in t - to - p o in t d iffe re n c e s appear not only re la te d to the s p a tia l arrangement o f p ro te c tio n devices along the shore 116 ii ♦ ***y > ' ^ r t <** ‘ /• ^ Predicted Bluf? L in e i n 2 0 7 5 M a y 27, 1975, Bluff Line - r T„ ci\ I '* »*•;? H 'l : ' rJ' * * > 11-’. •** *'■„«■-«•, ^ r ■:-■ W >'-'X’K-.'.A’:-:-: ^ & **' 25- V ;. * «*-? ' I October 28, 1941, Bluff Line ' . ■.* a ^-xss^: Figure 24. t , v , '• « '* , m iles May, 1975, a e ria l photograph o f the northern Kenosha County, Wisconsin, case study area showing the 22 s it e lo c a tio n s , the October 28, 1941, and May 27, 1975, b l u f f li n e s , and the p redicted b l u f f c re s t p o s itio n in 2075. This area is located in Sections 5, 7, and 8 / T2N,R23E. 117 W IS C O N S IN Figure 24 ( c o n t ' d . ). Table 14. S ite No. B l u f f recession rates a t the northern Kenosha County, Wisconsin case study s it e s , 1969 to 1975, 1941 to 1969, and 1941 to 1975. Average Annual Average Annual Average Annual B lu f f Recession B l u f f Recession B l u f f Recession B l u f f Recession B l u f f Recession B l u f f Recession 10/28/41-5/27/75 10/28/41-6/28/69 6/28/69-5/27/75 6/28/69-5/27/75 10/28/41-6/28/69 10/28/41-5/27/75 3.6 fe e t (0.33 m) 0.61 fe e t (0.186 m) 11.5 fe e t (3.51 m) 0.42 fe e t (0.128 m) 15.1 fe e t (4.60 m) 0.45 fe e t (0.137 m) K2 39.8 fe e t (12.13 m) 6.72 fe e t (2.048 m) 55.9 fe e t (17.04 m) 2.02 fe e t (0.616 m) 95.7 fe e t (29.17 m) 2.85 fe e t (0.869 m) K3 19.9 fe e t (6.07 m) 3.36 fe e t (1.024 m) 40.6 fe e t (12.37 m) 1.47 fe e t (0.448 m) 60.5 fe e t (18.44 m) 1.80 fe e t (0.549 m) K4 23.2 fe e t (7.07 m) 3.92 fe e t (1.195 m) 27.2 fe e t (8.29 m) 0.98 fe e t (0.299 m) 50.4 fe e t (15.36 m) 1.50 fe e t (0.457 m) K5 30.0 fe e t (9.14 m) 5.06 fe e t (1.542 m) 25.4 fe e t (7.74 m) 0.92 fe e t (0.280 m) 55.4 fe e t (16.89 m) 1.65 fe e t (0.503 m) K6 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) K7 9.2 fe e t (2.80 m) 1.56 fe e t (0.475 m) 27.0 fe e t (8.23 m) 0.76 fe e t (0.232 m) 30.2 fe e t (9.20 m) 0.90 fe e t (0.274 m) K8 12.7 fe e t (3.87 m) 2.15 fe e t (0.655 m) 37.7 fe e t (11.49 m) 1.36 fe e t (0.415 m) 50.4 fe e t (15.36 m) 1.50 fe e t (0.457 m) K9 5.4 fe e t (1.65 m) 0.91 fe e t (0.277 m) 123.1 fe e t (37.52 m) 4.45 fe e t (1.356 m) 117.7 fe e t (35.87 m) 3.51 fe e t (1.070 m) 118 K1 (W7) Table 14 ( c o n t 'd . ). Site No. Average Annual B lu f f Recession Average Annual B lu f f Recession Average Annual B l u f f Recession B l u f f Recession B l u f f Recession B l u f f Recession 6/28/69-5/27/75 6/28/69-5/27/75 10/28/41-6/28/69 10/28/41-6/28/69 10/28/41-5/27/75 10/28/41-5/27/75 K10 48.3 fe e t (14.72 m) 8.16 fe e t (2.487 m) 44.4 fe e t (13.53 m) 1.60 fe e t (0.488 m) 92.7 fe e t (28.25 m) 2.76 fe e t (0.841 m) K ll 7.7 fe e t (2.35 m) 1.30 fe e t (0.396 m) 12.3 fe e t (3.75 m) 0.44 fe e t (0.134 m) 20.0 fe e t (6.10 m) 0.60 fe e t (0.183 m) K12 9.4 fe e t (2.87 m) 1.59 fe e t (0.484 m) 10.6 fe e t (3.23 m) 0.38 fe e t (0.116 m) 20.0 fe e t (6.10 m) 0.60 fe e t (0.183 m) K13 13.3 fe e t (4.05 m) 2.24 fe e t (0.683 m) 6.7 fe e t (2.04 m) 0.24 fe e t (0.073 m) 20.0 fe e t (6.10 m) 0.60 fe e t (0.183 m) K14 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) K15 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) K16 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) K17 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) 0.0 fe e t (0.00 m) 0.00 fe e t (0.000 m) K18 5.8 fe e t (1.77 m) 0.98 fe e t (0.299 m) 11.7 fe e t (3.57 m) 0.42 fe e t (0.128 m) 17.5 fe e t (5.33 m) 0.52 fe e t (0.158 m) ...... ........ .. .. Table 14 ( c o n t 'd . ). S ite No. Average Annual Average Annual Average Annual B l u f f Recession B l u f f Recession B l u f f Recession B l u f f Recession 10/28/41-6/28/69 B l u f f Recession 10/28/41-5/27/75 B l u f f Recession 6/28/69-5/27/75 6/28/69-5/27/75 10/28/41-6/28/69 10/28/41-5/27/75 K19 5.5 fe e t (1.68 m) 0.92 fe e t (0.280 m) 7.0 fe e t (2.13 m) 0.25 fe e t (0.076 m) 12.5 fe e t (3.81 m) 0.37 fe e t (0.113 m) K20 15.0 fe e t (4.57 m) 2.53 fe e t (0.771 m) 7.5 fe e t (2.29 m) 0.27 fe e t (0.082 m) 22.5 fe e t (6.86 m) 0.67 fe e t (0.204 m) K21 3.7 fe e t (1.13 m) 0.63 fe e t (0.192 m) 56.8 fe e t (17.31 m) 2.05 fe e t (0.625 m) 60.5 fe e t (18.44 m) 1.80 fe e t (0.549 m) K22 21.5 fe e t (6.55 m) 3.63 fe e t (1.106 m) 6.1 fe e t (1.86 m) 0.22 fe e t (0.067 m) 27.6 fe e t (8.41 m) 0.82 fe e t (0.250 m) MEAN 12.5 fe e t (3.81 m) 2.11 fe e t (0.643 m) 23.3 fe e t (7.10 m) 0.84 fe e t (0.256 m) 34.9 fe e t (10.64 m) 1.04 fe e t (0.317 m) Mean Average Annual Lake Level Percent o f Period When Average Annual Lake Level Was Above the Modern Long-Term (1900-1977) Mean 1969 to 1975: 579.65 fe e t 1969 to 1975: 100 % 1941 to 1969: 578.05 fe e t 1941 to 1969: 44.8% 1941 to 1975: 578.34 fe e t 1941 to 1975: 54.3% 121 but also to v a ria tio n s in the natural processes operating in the nearshore environment. Groins, the most common p ro te c tio n s tru c tu re in the .area, have not prevented b l u f f r e tr e a t but recession rates are ge n e ra lly less severe where they e x is t . In some places where a series o f groins occur the b l u f f edge has taken on a somewhat scalloped or serrated appearance (Figure 24). At s it e K6 (Table 14 and Figure 24) two g ro in s , in s t a lle d p r io r to 1941, have apparently elim inated b l u f f l in e r e tr e a t f o r the time being (Figure 25). And long-term (1835 to 1976) recession a t the Kenosha-Racine county l i n e ( s i t e W7 in the main study and K1 in the case study) is 343.8 fe e t (104.79 m), but between 1941 and 1975 losses only amounted to 15.1 fe e t (4.60 m); o b vio u sly, since before 1941, g ro in s, and other subsequent s tru c tu r e s , have been e f f e c t iv e in g re a tly reducing b l u f f lin e r e tr e a t in t h is area. Natural a c c re tio n a ry processes probably account f o r the stable b l u f f lin e p o s itio n s at fo u r adjacent s ite s (K14-K17, Figures 24 and 26) in the southern section o f the study area. Situated in the lee o f a small headland, a low but r e l a t i v e l y broad beach te rra c e has fro n te d the b l u f f since at le a s t 1937 (Figure 27). In 1941 the fe a tu re extended about 1,000 fe e t along the shore and reached a maximum width o f approximately 200 fe e t. T y p ic a lly undergoing erosion and narrowing during high lake stages, i t widened a t times o f lower water le v e ls , although i t s average width has grown p ro g re ssive ly sm aller. Goldthwait (1907) discussed a s im ila r fe a tu re found about a m ile f a r th e r south. He described the beach te rra ce as a cuspate foreland which probably b u i l t from l i t t o r a l d r i f t deposited in the q u ie te r water back o f a headland (Figure 28). U n til now the beach te rra c e has prevented storm waves from reaching the b l u f f slope in the area under present in v e s t ig a t io n ; u n fo rtu n a te ly , these cond itio n s may not l a s t much longer. Recent high lake le v e l storm 122 Figure 25. S ite K6 in the South ^ / Section 5 / T2N.R23E, Kenosha County, Wisconsin. The two groins in the center o f the photo, i n s t a ll e d p r io r to 1941, have apparently so in fluenced shore co n d itio n s th a t no b l u f f lin e r e tr e a t has occurred since th a t date. This photo was taken on May 19, 1976. 123 Figure 26. Generally protected against storm waves by a broad beach te rra c e , the b l u f f in t h is p o rtio n o f Section 8 / T2N,R23W, Kenosha County, Wisconsin has undergone no c re s t recession since a t le a s t 1941. This photo was taken on May 19, 1976. 124 (A) August 12, 1937 1 1 *||*1 P 1 1 1 1 S » (B) September 6, 1950 (C) June 24, 1963 Figure 27. A e ria l photos taken in 1937, 1950, and 1963 showing the r e l a t i v e l y broad beach te rra ce fr o n tin g the b l u f f segment encompassing s ite s K14-K17. 125 Figure 28. G o ld th w a it's (1907) sketch map o f a cuspate fo re la n d located about one m ile south o f the northern Kenosha County, Wisconsin, case study area, showing the supposed eddies in the shorezone c u rre n t. This sketch is s im ila r to the beach co n d itio n s which have existe d along the shore fr o n t in g b l u f f s ite s K14-K17. 126 waves have eroded most o f i t s breadth and p a rt o f the small headland to the n o rth . Furthermore, a re c e n tly in s t a lle d groin on i t s northern edge appears to in t e r r u p t the southward moving l i t t o r a l d r i f t supply to the beach. Photographic and f i e l d data from the Kenosha and Shoreham case study areas demonstrate the dynamic nature o f the Lake Michigan shorezone during the past fo u r decades. B l u f f recession is re la te d to normal lakeshore processes and i t s ra te a t any p o in t is influenced by lo ca l and regional environmental co n d itio n s and by shorezone p ro te c tio n stru c tu re s . These a r t i f i c i a l s tru c tu re s are t y p i c a l l y in e f f e c t iv e in the long-term and are u n a tt r a c tiv e , p o t e n t i a l ly hazardous to shore users (Figures 29 and 30) and expensive. Based on previous and present events, b l u f f r e tr e a t may be expected to continue in the fu tu re . Future Rates o f B l u f f Recession Geomorphic processes have and w i l l continue to modify the Lake Michigan margin. Wise use o f any portio n o f the in c re a s in g ly high value shore!and depends on an assessment o f i t s v u ln e r a b i l i t y to fu tu re erosion. But severe lim it a t io n s are placed on a ccu ra te ly fo re ca stin g t h is erosion because the v a ria b le s in flu e n c in g the erosion are many and t h e i r in t e r r e la t io n s h ip s are often not well understood. Nevertheless, t h is study provides a method o f p re d ic tin g fu tu re b l u f f c re s t positio n s which is a p p lic a b le to the two case study areas. The procedure requires d e ta ile d knowledge o f previous b l u f f recession rates f o r the area o f in t e r e s t and the h i s t o r i c record o f mean monthly lake le v e ls . From th is data a re pre s e n ta tiv e b l u f f r e tr e a t value is determined which is then m u lt ip lie d by a lake le v e l fa c to r to e s ta b lis h an estimate o f the fu tu re b l u f f c re s t p o s itio n . 127 Figure 29. B l u f f p ro te c tio n measures in the North % / Section 8 / T2N,R23E, Kenosha County, Wisconsin. This photo was taken on J u ly 30, 1978 128 Figure 30. Broken concrete slabs armoring the b l u f f slope in the South % / Section 8 / T2N,R23E, Kenosha County, Wisconsin. This photo was taken on Ju ly 30, 1978. 129 Methodology fo r P re d ictin g Future B l u f f Crest Positions Period o f Record and Data Base The period o f record on which fu tu re recession rates are based must be selected w ith care. As emphasized e a r l i e r (Tables 13, 14 and 16) average annual b l u f f lin e r e tr e a t may vary s i g n i f i c a n t l y depending on the in te r v a l between measurements. For example, mean recession rates f o r the Shoreham area are markedly higher between 1967 and 1977 than between 1938 and 1967, or 1938 and 1977. To p re d ic t the fu tu re c re s t lin e p o s itio n based s o le ly on the high rates o f the present period would be m isleading; th is time span is noted not on ly f o r i t s high lake elevations but also fo r the persistency o f those le v e ls , a co n d itio n which is s in g u la r to t h is century. An adequate data base period p re fe ra b ly should encompass a t le a s t two stages o f lower, and two episodes o f hig h e r, lake e le v a tio n s . Thus, t o t a l b l u f f recession and the derived mean y e a rly r e t r e a t ra te would r e f l e c t periods characterized by both low and high recession values. For a given b l u f f segment i t is also necessary f o r p re d ic tio n s o f fu tu re b l u f f lin e p o s itio n s to be based to a considerable e xtent on recession data from a modern period o f record. Retreat rates derived from comparison o f modern b l u f f lin e s to cre sts a t the time o f the o r ig in a l land surveys alone are inadequate f o r lo ca l p re d ic tio n s because p o te n tia l data s ite s are too w idely spaced f o r meaningful assessments to be made. More appropriate is to use o ld e r a e ria l photography as a base from which rates a t numerous points w ith in sh o rt distances can be determined by comparing the photos w ith recent imagery. Photography is g e n e ra lly a v a ila b le f o r the Lake Michigan shorezone since the la te 1930's and e a rly 1940's and since th a t period three low and three high lake 130 stages have occurred. Furthermore, modern rates o f r e tr e a t b e tte r r e f l e c t the in flu e n c e o f shorezone p ro te c tio n s tru c tu re s whose numbers have increased s u b s t a n tia lly during the l a s t 30 years. Representative B l u f f Retreat Value f o r the Period o f Record For each sho re line m ile i t is g e n e ra lly accepted th a t a minimum o f fo u r (M artin JannerethJ personal communication) or f iv e ( S ta ffo rd , 1971; Tanner, 1978) measurements a t s i m ila r ly spaced s ite s over an adequate period o f time is necessary to e s ta b lis h a repre se n ta tive recession value. For those lakeshore reaches where sample s ite s have s im ila r recession ra te s , a s in g u la r re p re se n ta tive value may be established by computing the mean value o f the in d iv id u a l s ite s . A more d i f f i c u l t problem a rises where recessional losses o f adjacent or nearby s ite s w ith in a zone vary co n siderably, as they commonly do where shore p ro te c tio n s tru c tu re s e x is t or have existe d during the period o f record. In such cases extreme in d iv id u a l s it e values can g re a tly in flu e n c e the mean and lead to erroneous conclusions (B la lo c k , 1972). A more r e lia b le in d ic a to r may be to rank the in d iv id u a l values and to use the median fig u re as the rate most " t y p i c a l" or re p re se n ta tive (B la lo c k , 1972) o f the lakeshore segment. In d iv id u a l s i t e values should be examined fo r consistency before e s ta b lis h in g a median r e tr e a t ra te . It may be advantageous to d iv id e the length in to two or more zones, each being assigned a d i f f e r e n t median value. This may occur i f o v e ra ll s i t e values s i g n i f i c a n t l y change from one shoreline reach to another. However, segments would not be divid e d i f adjacent s ite s repeatedly d is p la y ^Mr. Jannereth is responsible f o r the Michigan Department o f Natural Resources' program to determine b l u f f recession rates along the s t a t e 's Great Lakes shorezone. 131 s i g n i f i c a n t l y d i f f e r e n t values, as they may do where shore p ro te ctio n s tru c tu re s p a r t i a l l y p ro te c t the b l u f f . Because o f the p o in t - t o - p o in t v a r i a b i l i t y o f b l u f f r e tr e a t values, in t h is study the median r e tr e a t value (ascertained from a l l a v a ila b le recession rates w ith in the zone o f in t e r e s t ) is considered a more meaningful and re p re s e n ta tiv e fig u re in the p re d ic tio n procedure than the mean value. In areas in c o rp o ra tin g s ite s w ith s im ila r recessional rates the median would be very close to the mean but in those reaches where in d iv id u a l losses vary considerably the median fig u re may not be s im ila r (B la lo c k , 1972). Lake Level Factor and P re d ic tio n o f Future B l u f f Retreat Berg and C o llinson (1976) found th a t b l u f f erosion from wave a tta ck in I l l i n o i s becomes s i g n if ic a n t when water e le va tio n s r is e above 579 f e e t. Although a t some places b l u f f r e tr e a t may occur below th a t le v e l, and a t others erosion may not happen u n t il the lake is well above th a t measure, o v e r a ll , Berg and C o llin s o n 's estim ate seems reasonable f o r the case study areas. I f the 579 fo o t le v e l is a threshold above which most b l u f f l in e losses occur the duration o f time when the lake is above t h i s mark becomes e s p e c ia lly s i g n if ic a n t . In most studies e stim a tin g fu tu re b l u f f c re s t lo c a tio n s , the p o s itio n s are esta b lish e d by m u ltip ly in g the average annual b l u f f r e tr e a t value derived from the period o f record f o r the p a r t ic u la r lakeside segments by the number o f years in to the fu tu re the in v e s tig a to rs wished to fo re c a s t. As long as the period o f record spanned a t le a s t a high and low lake le v e l in te r v a l the s p e c if ic number o f months o r percentage o f time when the le v e ls were a c tu a lly high during the period was given little a t t e n tio n . I f long-term p re d ic tio n s are to be reasonable t h is fa c to r must be considered. 132 Two assumptions are made in order to incorporate a fu tu re lake le v e l f a c t o r in the p re d ic tio n procedure: (1) The h is t o r i c record o f lake le v e ls is a v a lid in d ic a to r o f fu tu re c o n d itio n s . For example, during the next hundred years lake le v e ls can be expected to be above the 579 fo o t mark a length o f time s im ila r the previous one hundred years. to the amount i t was during And ( 2 ) , during the period o f record (from which recessional values are established fo r a p a r t ic u la r shore segment) s ig n if i c a n t b l u f f l in e losses occurred only during those months when the lake was above the 579 fo o t e le v a tio n . On t h is basis a fu tu re r e tr e a t value, in co rp o ra tin g a lake level f a c t o r , can be devised f o r a shorezone segment by: (1) Determining the number o f months w ith in the period o f record (from which r e tr e a t values are derived) when water e le vations were above 579 fe e t. (2) D ivid in g the median r e tr e a t value f o r the period o f record by the number o f months established in (1 ). (3) Selecting the fu tu re reference date and determining the number o f years (X) between then and the end o f the period o f record. (4) Determining the number o f months during the p re d ic tio n period when, based on h i s t o r i c lake le ve l readings f o r X years, the lake could be expected to be above the 579 fo o t le v e l. (5) M u ltip ly in g the average monthly recessional value, derived in ( 2 ) , by the number o f months the lake is expected to surpass the 579 fo o t e le v a tio n , derived in (4 ). Thus, based on known recession data from a previous p e rio d , an average monthly r e tr e a t value is assigned o n ly to those months when Lake Michigan's 133 e le va tio n is above 579 f e e t. This fig u r e then becomes the projected monthly ra te o f r e tr e a t during each month in the fu tu re when the la k e 's average height is expected to ra is e above 579 f e e t ; below th is le v e l b l u f f recession is not a n tic ip a te d . Problem: For example: P re d ict the amount o f b l u f f li n e r e tr e a t th a t w i l l take place along a one m ile shoreland segment during the next one hundred years. Established: (1) Twelve sample s ite s fo r which the median r e tr e a t value f o r a 35 year period o f record is 70 fe e t ( 2 .0 0 '/ y r ) . (2) The lake le ve l was above 579 fe e t fo r 120 months during the 35 year period o f record. I f b l u f f recession only occurred during months when the mean lake le v e l was above 579 f e e t , the average ra te o f r e tr e a t during each o f these months would then be: 70‘ 120 months (3) = 0.583'/month For one hundred years p r io r to the end o f the period o f record, the mean monthly water e le va tio n was above the 579 fo o t mark during 360 months. Predicted Future R etreat: 0 .5 8 3 '/month x 360 months = 209.9 fe e t 134 B l u f f Crest Positions In the Next Century Two Case Study P red ictio n s Shoreham B l u f f r e tr e a t was determined a t 15 s ite s in Shoreham fo r the period o f record June 5, 1938 to A p r il 27, 1977 (Table 13). Median r e tr e a t f o r the area was 112.1 fe e t ( 2 . 8 8 '/ y r ; 34.17 m or 0.878 m /y r).^ During t h is time Lake Michigan's le v e l was above 579 fe e t fo r 141 o f the 467 months. And f o r a l l months during the 100 years p r io r to A p r i l , 1977, th is same mean monthly le ve l was exceeded on 413 occasions. D iv id in g 112.1 fe e t by 141 months, and m u ltip ly in g the r e s u ltin g q u o tie n t by 413 months, a r e tr e a t o f 328.3 (100.13 m) is a n tic ip a te d during the next century along the Shoreham b lu f f s (Figure 18). At only one s it e (Ml) in the area is a long-term recession value a v a ila b le and the a n tic ip a te d ra te o f r e tr e a t ( 3 . 2 9 '/ y r or 1.003 m /yr) is s u b s t a n tia lly g rea te r than the ra te experienced by the measured s it e ( 1 . 8 8 '/ y r or 0.573 m/yr between 1829 and 1977). Apparently the higher a n tic ip a te d ra te r e f le c t s the rapid increase in b l u f f recession during the l a s t fo u r decades due la r g e ly to the adverse e ffe c ts created by the St. Joseph harbor j e t t i e s and oth e r shore p ro te c tio n s tru c tu re s . The 1 . 8 8 '/ y r (0.573 m /yr) r e tr e a t value f o r s it e Ml, however, encompasses a la rg e time span in the 1800's and e a rly 1900's when the b l u f f l in e was unaffected by s tru c tu re s and remained r e l a t i v e l y sta b le (Table 14). Under present co n d itio n s b l u f f recession during the next 100 years may be expected to cause the d e s tru c tio n o f no fewer than 33 homes, nine o th e r b u ild in g s , three swimming pools, and a tennis c o u rt. ^Mean r e tr e a t f o r the 10 s ite s is 52.8 fe e t ( 1 . 5 7 '/ y r ; 15.09 m or 0.479 m /y r). 135 Furthermore, the i r r e g u l a r i t y o f the b l u f f lin e w i l l l i k e l y continue, and may increase, but because o f the temporal and d is ju n c t nature o f shore p ro te c tio n s tru c tu re s i t is not possible to p re d ic t a s p e c ific b l u f f 1ine p a tte rn . Northern Kenosha County In Kenosha County modern recession rates were based on the period o f record October 28, 1941 to May 27, 1975 (Table 15). During t h is time b lu f f s along the northern and southern portions o f the study area receded a t s i g n i f i c a n t l y d is s im ila r ra te s . Therefore, a d if f e r e n t re presentative b l u f f r e tr e a t value was established f o r each segment. Median r e tr e a t f o r the northern b l u f f l i n e , corresponding to s ite s K1 through K10, was 50.4 fe e t (1 .5 0 */ y r ; 15.36 m or 0.457 m /y r).^ Median recession f o r the southern segment, c o in c id in g w ith s ite s K ll through K22, was 20 fe e t ( 0 . 6 0 '/ y r ; 6.10 m or 0.183 m / y r ) . ^ The b l u f f lin e along the northern s tre tc h can be expected only to be about 167.9 fe e t hundred years. 11 (51.15 m) in land from i t s present p o s itio n in one At th a t time the southern c re s t l in e is expected only to have receded 66.6 fe e t 1? (20.30 m) (Figure 24). The d iffe re n c e in b l u f f r e tr e a t between +he northern and southern segments n ic e ly i l l u s t r a t e s the v a r i a b i l i t y o f recession along the Lake Michigan s h o re lin e . I f these v a ria b le co n d itio n s are widespread i t is important ^Mean r e tr e a t f o r the 10 s ite s is 52.8 fe e t ( 1 . 5 7 '/ y r ; 16.09 m or 0.479 m /yr). ^Mean r e tr e a t f o r the 12 s ite s is 21.2 fe e t ( 0 . 6 7 '/ y r ; 6.46 m o r 0.204 m /yr). ^ T h e value o f 167.9 fe e t is the r e s u lt o f d iv id in g 50.4 fe e t by 124 months, and m u lt ip ly in g the r e s u ltin g q u o tie n t by 413 months. ^ T h e value o f 66.6 fe e t is the r e s u lt o f d iv id in g 20 fe e t by 124 months, and m u ltip ly in g the r e s u ltin g q u o tie n t by 413 months. 136 fo r wise land use to i d e n t i f y those areas o f the shorezone th a t are e s p e c ia lly susce p tib le to erosion. The projected ra te o f r e tr e a t is less than the long-term recession rates established f o r three s ite s w ith in the study area ( s ite s W5, W6, and W7, p. 112). This is because modern r e tr e a t values have been less than previous periods, a c o n d itio n th a t may be p a r t ly due to p ro te c tiv e s tru c tu re s along the shore. I t is p o s s ib le , though, th a t b l u f f recession in the v i c i n i t y o f s ite s K13 through K17 may prove to be greater than projected based on the p re d ic tio n technique. During the modern period o f record t h is b l u f f segment was buffered against wave erosion by a r e l a t i v e l y wide beach te rra c e (Figure 25). This te rra c e , however, has been la r g e ly removed and co n d itio n s are such th a t i t may not reform. In such a case, fu tu re b l u f f r e tr e a t w i l l s u re ly be greater than the modern record would in d ic a te . Based on the estimated 100-year b l u f f l in e p o s itio n a t le a s t 41 e x is t in g b u ild in g s would be destroyed and the main highway between the c i t i e s o f Kenosha and Racine would be threatened. These stru ctu re s may not be saved but fu tu re damage can be lim it e d by preventing f u r th e r co n s tru ctio n w ith in the zone o f l i k e l y b l u f f top r e t r e a t . I t is only prudent to e s ta b lis h zoning setback requirements and p r o h ib it s itu a tio n s such as found in Figure 31. 137 Figure 31. Unwise c o n s tru c tio n along the Kenosha County, Wisconsin shorezone. Long-term b l u f f recession in t h i s v i c i n i t y has been about f i v e fe e t per year. This lo c a tio n is a t the C e n te rline / Section 17 / T1N.R23E. Chapter 5 SUMMARY AND CONCLUSIONS The conclusions o f t h is study are summarized below as they re la te to the three basic o b je c tive s o f the d is s e r ta tio n . The f i r s t purpose is "To determine long-term b l u f f c re s t recession at a number o f s ite s along the Michigan and Wisconsin lakeshores and to compare these fin d in g s w ith selected c h a r a c te r is tic s o f the shorezone." Long-term b l u f f l in e changes are determined at 118 lo c a tio n s , 62 in Wisconsin and 56 in Michigan. In d iv id u a l s ite s and extended reaches on both sides o f Lake Michigan d is p la y wide v a r i a b i l i t y in these changes. Long-term recession cannot be re la te d in a meaningful way w ith sediments or sediment arrangements f o r b lu f f s composed o f none o lia n m a te ria l. In c o n tra s t, dune b lu f f s are g e n e ra lly receding at s i g n i f i c a n t l y lower long-term rates than b l u f f s composed o f non-dune sediments. Although dune b lu f f s are probably no le s s , and may even be more, susceptible to r e t r e a t from wave erosion than are b lu f f s formed in non-dune m a te r ia l, t h e i r t y p i c a l l y lower long-term values are a t t r ib u t a b le to dune a ccretion during low lake le v e l episodes. Consequently, a t sand dune lo c a tio n s net long-term recession rates tend to be lower but gross long-term losses may be greater than a t non-dune s it e s . V a ria tio n s in rates o f long-term recession cannot be d i r e c t l y c o rre la te d to fa c to rs o f ground water a c t i v i t y and b l u f f h e ig h t. Ground water seepage, nonetheless, appears to be an im portant c o n tr ib u to r to 138 139 b l u f f slope i n s t a b i l i t y ; in general, t h is co n d itio n is probably more detrim ental to the Wisconsin than to the Michigan lakeshore b l u f f s . Because perched water tables are common in most high non-dune b lu f f s they may a t le a s t p a r t i a l l y account f o r the lack o f c o r r e la tio n between b l u f f heights and rates o f r e t r e a t . Shoreline o r ie n ta tio n and fe tch appear to in flu e n c e rates o f r e tr e a t but beach width cannot be m eaningfully re la te d to long-term b l u f f recession values. The second o b je c tiv e is "To t e s t the hypothesis th a t w ith in the segments examined b l u f f c re s t recession is greater on the eastern side o f the la k e ." S ite data, however, in d ic a te th a t long-term b l u f f recession along the opposite shores is s t a t i s t i c a l l y s im ila r . Although the Michigan lakeside may expect a higher incidence o f incoming deep water storm waves, the strong in flu e n c e o f foredune regeneration and b e tte r development o f energy d is s ip a tin g beaches and longshore sand bars on the eastern shorezone probably account fo r Michigan's rates resembling those o f Wisconsin. Findings also d isclo se th a t s ite s in the southern p o rtio n o f both lakeshores tend to e x h ib it higher than average r e tr e a t ra te s , and in Wisconsin recession values are s i g n i f i c a n t l y lower n o rth , than south, o f the c i t y o f Port Washington. The t h i r d o b je c tiv e is "To in v e s tig a te two areas in d e ta il and to p re d ic t fu tu re b l u f f c re s t p o s itio n s and suggest possible consequences r e s u ltin g from r e tr e a tin g b lu f f s a t these lo c a tio n s ." Modern rates o f b l u f f l in e change are determined f o r the Shoreham, Michigan, and northern Kenosha County, Wisconsin, case study areas where most s ite s experienced re tre a t. Average annual rates vary w ith the in te r v a l between measurements. Generally the highest rates correspond to periods which contain the 140 g rea te st percentage o f years when lake le v e ls are high. Furthermore, modern rates are found not to be s im ila r to long-term r e tr e a t values in the areas stu d ie d . This co n d itio n is la r g e ly a t t r ib u t a b le to the s u b s ta n tia l increase in shore p ro te c tio n s tru ctu re s during the modern era. The temporal and d is ju n c t p attern o f these stru ctu re s g re a tly in flu e n c e the p o in t - t o - p o in t v a r ia tio n in recession rates and account f o r the increasing i r r e g u l a r i t y in b l u f f appearance. O v e ra ll, data imply th a t b l u f f p ro te c tio n s tru c tu re s have an adverse e f f e c t on shorezone c o n d itio n s . A method o f p r e d ic tin g fu tu re b l u f f c re s t p o sitio n s is also suggested. Using a f a c t o r re la te d to the 579 fo o t lake l e v e l, b l u f f l in e p o s itio n s are fo re c a s t fo r the next century in the case study areas. Projected r e tr e a t fo r the Shoreham segment is greater than previous long-term rates esta b lish e d f o r the area but expected recession fo r the Kenosha County reach is less than past long-term records in d ic a te . The c o n f l i c t between past and projected rates o f r e tr e a t is la r g e ly cre d ite d to the in flu e n c e o f shore p ro te c tio n s tru c tu re s . Suggestions f o r Future Research During the study i t became apparent th a t c e rta in subjects deserve a d d itio n a l in v e s t ig a t io n . F i r s t , since foredune regeneration appears to re ta rd long-term b l u f f recession, the r e la tio n s h ip between modern foredunes and fa c to rs in flu e n c in g t h e i r development and uneven d i s t r i b u t i o n , and t h e i r a c cretio n and erosion ra te s , need to be b e tte r understood. Second, i t may be h e lp fu l to e s ta b lis h the r e la tio n s h ip between s h o rt-te rm recession (a c c re tio n ) rates and the length o f a given high (low) lake le v e l p e rio d , and the frequency o f change between episodes o f above and below average water e le v a tio n s . T h ird , although a few studies have 141 focused on a sc e rta in in g incoming deep water wave energy along the Michigan and Wisconsin shores, there is a need to determine, over wide areas and under varying c o n d itio n s , the amount o f incoming shallow water wave energy which a c tu a lly reaches the beach and b l u f f zone and to r e la te these data to rates o f r e tr e a t . And l a s t , i t would be advantageous to determine more p re c is e ly the accumulated e f f e c t which increasing numbers o f shorezone p ro te c tio n stru c tu re s have had, and w i l l continue to have, on l i t t o r a l processes and b l u f f lin e e v o lu tio n . APPENDICES APPENDIX A SHOREZONE TERMINOLOGY USED IN THIS STUDY Shorezone term inology used in t h is study is defined in Table A l. 142 143 Table A l. Shorezone terminology used in t h is study. Backshore The zone o f the shore or beach ly in g between the foreshore and the shoreland and acted upon by waves on ly during severe storms, e s p e c ia lly when combined w ith e x c e p tio n a lly high water (Veatch and Humphrys, 1964). Bank A landward-facing steep b l u f f o r sharp slope o f unconsolidated m aterial landward o f the s h o re lin e ; the b l u f f . Beach A shore o f unconsolidated m a te r ia l, usually sand and/or pebbles (U.S. Army Corps o f Engineers, 1973c). B lu ff A lakeward-facing steep bank or sharp slope o f unconsolidated m aterial landward o f the s h o re lin e ; the bank. B l u f f Base The p o in t o r l i n e o f abrupt change in slope a t the bottom o f the b l u f f ; the b l u f f toe. B l u f f Crest The p o in t o r l i n e o f abrupt change in slope a t the top o f the b l u f f ; the b l u f f li n e . B l u f f Face The lakeward facing in c lin e d surface o f the b l u f f ; the b l u f f slope. B l u f f Line The p o in t or l in e o f abrupt change in slope at the top o f the b l u f f ; the b l u f f c re s t. B l u f f Toe The p o in t o r l in e o f abrupt change in slope a t the bottom o f the b l u f f ; the b l u f f base. B l u f f Slope The lakeward-facing in c lin e d surface o f the b l u f f ; the b l u f f face. Breaker Zone The area o f water bounded by the beach and the plunge l i n e ; the plunge l in e is the l in e along which the highest waves break (Russell and MacMillan, 1970). Breakwater A s tru c tu re p ro te c tin g a shore area, harbor, anchorage, o r basin from waves; i t is u s u a lly p a r a lle l to the shore and b u i l t in the nearshore zone (U.S. Army Corps o f Engineers, 1973c). 144 Table Al ( c o n t 1d . ). Foredune The f r o n t sand dune im nediately behind the backshore (U.S. Army Corps o f Engineers, 1972c). Foreshore The p a rt o f the shore, o r beach, norm ally covered by the uprush and backrush o f waves (Veatch and Humphrys, 1965). Groin A shore p ro te c tio n s tru c tu re b u i l t u s u a lly perpendicular to the sho re line in order to tra p l i t t o r a l d r i f t or re ta rd erosion o f the shore (U.S. Army Corps o f Engineers, 1973c). Inshore (Zone) The zone o f v a ria b le width extending from the sho re line through the breakwater (Gray, McAfee, and Wolf, 1972); e s s e n t ia lly the same as the l i t t o r a l zone. J e tty A s tru c tu r e extending in to a body o f water designed to prevent shoaling o f a channel by l i t t o r a l m aterial and to d ir e c t and confine stream flo w (U.S. Army Corps o f Engineers, 1973c). Lakeshore A general term used to denote the margin o f the lake or a p a r t ic u la r side o f the lake. I t does not r e fe r to a s p e c ific area w ith in the shorezone; the lakeside. Lakeside A general term used to denote the margin o f the lake or a p a r t ic u la r side o f the lake. I t does not r e fe r to a s p e c ific area w ith in the shorezone; the lakeshore. L i t t o r a l Current Any c u rre n t in the l i t t o r a l zone (inshore zone) caused p r im a r ily by wave a c tio n , e . g . , a longshore or r i p c u rre n t (U.S. Army Corps o f Engineers, 1973c). L itto ra l D r ift The sedimentary m aterial moved in the l i t t o r a l zone under the in flu e n c e o f waves and currents (U.S. Army Corps o f Engineers, 1973c). 145 Table Al ( c o n t ' d . ). L i t t o r a l Zone An in d e f in it e zone extending lakeward from the shoreline to j u s t beyond the breaker zone (U.S. Army Corps o f Engineers, 1973c); e s s e n tia lly the inshore zone. Longshore Sand Bar A low, elongate submerged sand r id g e ( s ) , b u i l t c h ie f ly by wave a c tio n , occurring at some distance from, and extending ge n e ra lly p a r a lle l w ith , the s h o re lin e , and t y p i c a l l y separated from the beach by an inte rve n in g tro u g h (s) (Gary, McAfee, and Wolf, 1972). Longshore Current The l i t t o r a l current in the breaker zone moving e s s e n tia lly p a r a lle l to the shore, u su a lly generated by waves breaking a t an angle to the shoreline (U.S. Army Corps o f Engineers, 1973c). Longshore D r i f t The m aterial transported by a longshore cu rre n t (American Geological I n s t i t u t e , 1974). Nearshore (Zone) The in d e f i n i t e zone extending from the shoreline well beyond the breaker zone d e fin in g the area o f nearshore c u rre n ts , and in clu d in g the inshore zone and part o f the o ffshore zone (Gary, McAfee, and Wolf, 1974). Nearshore Current System The cu rre n t system caused p r im a r ily by wave a ction in and near the breaker zone; fo u r main components comprise the system: the shoreward mass tra n s p o rt o f water, longshore c u rre n ts , lakeward re tu rn flo w , in clu d in g r i p c u rre n ts , and the longshore movement o f the expanding heads o f r i p currents (U.S. Army Corps o f Engineers, 1973c). Offshore (Zone) The shallow bottom lakeward o f the breaking waves (Bloom, 1978); t h is zone is o f v a ria b le width and is lakeward o f the inshore zone (Gary, McAfee, and Wolf, 1972; U.S. Army Corps o f Engineers, 1973c). Revetment A facing o f stone, concrete sla b s, e tc. b u i l t to p ro te c t a scarp, embankment, o r shore s tru c tu re against erosion by wave a ction or currents (U.S. Army Corps o f Engineers, 1973c). 146 Table Al ( c o n t1d . ). Rip Current A strong cu rre n t flo w in g lakeward from the shore (U.S. Army Corps o f Engineers, 1973c). Riprap A la y e r , fa c in g , o r p ro te c tiv e mound o f stones randomly placed to prevent erosion, scour, or sloughing o f a s tru c tu re or embankment; also the stone so used (U.S. Army Corps o f Engineers, 1973c). Seawall A s tru c tu re separating land and water areas, p r im a r ily designed to prevent erosion and other damage due to wave a ction (U.S. Army Corps o f Engineers, 1973c). Shore The zone lakeward o f the shoreland over which the ground is a l t e r n a t iv e ly exposed and covered by waves; the shore's upper boundary is the lakeward l i m i t o f e ff e c t iv e wave a c tio n at the base o f the b lu f f s and i t s lakeward l i m i t is the water l i n e . It may be subdivided in to a foreshore and a backshore (Gary, McAfee, and Wolf, 1972). Shoreland The zone o f land o f i n d e f in it e width th a t extends from the base o f the b lu f f s inland to the f i r s t major change in t e r r a in fe a tu re ; the b l u f f is the lakeward margin o f the shoreland (Gary, McAfee, and Wolf, 1972). In essence, i t is the lake margin e q uivalent o f "c o a s t," which is an ocean o r sea margin term (Veatch and Humphyrs, 1964). Shoreline The l in e separating water and the land; the water li n e . Shorezone The combined nearshore zone, shore, and shoreland. Water Line The lin e separating water and the land; the sh o re lin e . APPENDIX B SELECTED CHARACTERISTICS OF THE WISCONSIN AND MICHIGAN STUDY SITES Selected c h a r a c te r is tic s o f the Wisconsin study s ite s are described in Table B1 and those o f the Michigan s ite s are displayed in Table B2. 147 Table Bl. Selected c h a ra c te ris tic s o f the Wisconsin study s ite s . Key To The Table B l u f f S tratigraphy ds: Dune sand; eolian deposits o f sand size p a r tic le s . ws: W ater-laid sand; water-deposited sand size p a r t ic le s , w ith and w ithout pebbles, and to include th in interbedded zones w ith high percentage o f clay or s i l t - s i z e p a r tic le s . c l: Clay; water-deposited sediments o f a clay or s i l t y - c l a y te x tu re . t: T i l l ; n o n - s t r a t if ie d , non-sorted g l a c i a l l y deposited sediments which at the study s ite s are normally o f a clay loam te xtu re and which u su a lly include pebbles and/or cobbles. cov: Covered; the b l u f f s tra tig ra p h y is obscured by overburden. "Recent Erosion" "Recent" re fe rs to any time during the present high lake stage (since 1968). 00 Table B1 S ite No. (cont'd.). Generalized B lu ff S tra tig ra p h y Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 B lu ff Height MassShore- "Recent" "Recent" V is ib le Erosion Erosion Ground Movement 1ine O rienta­ At B lu f f At B l u f f Water On Slope Below Seepage Crest tio n Base Crest KENOSHA COUNTY W1 -7 .5 6 ' 2 ' -ws 2' N17%°W Yes Yes No Yes W2 -6 .9 7 ' l'- w s 1' N7%°W Yes Yes No Yes W3 -6 .3 3 ' 5'-ws 5‘ N2%°W Yes Yes No Yes W4 -2 .4 5 ' 5 '-d s / 14'-ws 19' N4°W Yes Yes No Yes W 5° -2 .7 4 ' 4V-ws / 2 8 V - c l 33' N8°E Yes Yes Yes Yes W 6b -2 .4 3 ' 6V -w s / 10%'- c l / 6 V -c o v / 4 '-cl / 4 '- 1 31%' N15°E Yes Yes Yes Yes RACINE COUNTY* W/ -2 .4 4 ' 8 '-ws / 2 2 '- t 30' N8°E Yes Yes Yes Yes W 8* -0 .8 5 ' 3'-ws / 2 8 '- t 31' N12%°E Yes Yes No Yes W9 -0 .9 4 ' 20' - 1 20' N35%°E Minor No No No W10 -1 .8 7 ' 1 5 '-ws / 9 ' - t 24' N48°W Yes Yes No Yes Table B1 ( c o n t ' d . ) . B lu ff Height Generalized B lu ff S tratigraphy MassShore­ "Recent" "Recent" V is ib le Movement Ground Erosion Erosion lin e O rienta­ At B l u f f At B l u f f Water On Slope Below Seepage Crest Base tio n Crest S ite No. Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 Wll -1 .2 4 ' 31' - 1 31' N45°W Yes Yes No Yes W12 -1.77' 2*- c l / 5 2 '- t 54' N34°W Yes Yes No Yes 90' N17°W Yes Yes Yes Yes MILWAUKEE COUNTY W13 -3 .2 9 ' 7 7 '- t / 6 ' - c l / 7 ' - t W14 -1 .0 4 ' 8 ' - t / 17%'-ws / 7 ' - c l / 57%'-cov 90' N: N6 °E S: N7%°E Yes Yes Yes Yes W15 -0 .6 5 ' 1 5 '- t / 2 3 '-ws / l l ' - c l / 3'-ws / 6 ' - c l / 27'-cov 85' N: N3°E S: N8 °W Yes Yes Yes Yes W16# -0 .8 1 ' 701-1 g ly cov (prob. complex) 70' N1°W No Minor No Yes OZAUKEE COUNTY W17 -0 .1 3 ' 30*- t / 2 8 '-ws / 2 2 '- c l 80' N30%°W Yes No Yes Yes W18* -1.97' 15 '- t / 80'-cov 95' N28%°W Yes Yes Yes Yes W19 -2 .3 4 ' 1 0 0 '-cov (prob. complex) 100' N14°W Yes No No Yes Table B1 ( c o n t ' d . ). B lu ff Height MassShore­ "Recent" "Recent" V is ib le Movement Ground Erosion Erosion lin e O rienta­ At B lu f f At B lu f f Water On Slope Below Seepage Base Crest tio n Crest Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 Generali zed B lu ff S t r a ti graphy W20 -2 .5 7 ' 6 0 '- t / 15'-ws / 8 ' -cov / 3 ' - c l / 24'-cov (prob. mostly c l) 110' N7°E Yes Yes Yes Yes W21 -2 .5 5 ' 1 1 0 '-cov (prob. complex) 110' N11°E Yes Mi no Yes Yes W22 -2 .9 0 ' 1 1 0 '-cov (prob. complex) 1 10 ' N13°E Yes Yes Yes Yes W23 -2 .5 8 ' ? ' -cov / ? ' - t / 2 2 '-ws / 2 1 ' - c l / 7 ' -cov 120' N25°E Yes N: Minor S: Yes Yes Yes W24 -2 .9 4 ' llO '- c o v (prob. complex) 110' N4°E Yes Yes Yes Yes W25 -1 .4 4 ' poorly exposed: 4 7 '- t / 2'-ws / 1 2 '- t / 5'-ws / 1 9 '- t 85' N10°E Yes Yes Yes Yes W26h -0 .4 1 ' 2 5 ' - 1 / 20'-cov / 5 ' - c l / 1 5 V -w s / 1 1 ' - c l / 2 ' - t / 1 2 '-cov 90' N: N15°E S: N6V E Yes Yes Yes Yes W27 - 0 . 12' 2 ' -ws 2' N14VE Yes Yes No Yes W28 - 0 .2 0 ' 3'-ws 3' N13%°W Yes Yes No Yes 3' N: N16°W S: N8 °E Yes Yes No Yes S ite No. SHEBOYGAN COUNTY W29 -0 .2 3 ' V - d s / 2V-ws Table B1 ( c o n t1d . ). S ite No. Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 Generalized B lu ff S tr a t i graphy B lu f f Height MassShore­ "Recent" "Recent" V is ib le Ground Movement Erosion Erosion lin e O rienta­ At B lu f f At B lu f f Water On Slope Below Crest Seepage tio n Base Crest N9°E Yes Yes No Yes 4-5' N29°E Yes Yes No Yes V - d s / 2V-ws 3' N25%°E Yes Yes No Yes -0 .7 2 ' l ' - d s / 4'-ws 4* N32°E Yes Yes No Yes W34 +0.05* 2 '-d s / 4'-ws 6' N28°E Yes Yes No Yes W35 +0.06' 3'-ds / 3'-ws 6' N30°E Yes Yes No Yes W36 -1 .0 9 ' 51-ds / 4'-ws 9' N: N3°W S: N12°E Yes Yes No Yes W37 -1 .0 7 ' 1 0 ' -ws / 2 8 '- c l 38' N24°W Yes Yes Yes Yes W38 -1 .0 3 ' 7V-ws / 5 1- c l / 2 V - t / 8 ' - ws & cl / 1 0 ' -cov 33' N: N7%°W S: N22°W Yes Yes Yes Yes W39 -0 .9 2 ' 221- t / 4'-ws / 101- c l / 8 ' -cov (prob. c l ) 44' n^ ow Yes Yes Yes Yes W40* - 1. 10' 4'-ws / 9 1- t 13' Hh°E Yes Yes No Yes W41 -1 .0 7 ' 6 '-ws / 5 ' - t / 7'-ws / 46' N13°W Yes Yes Yes Yes W30 +0.37' 5 '-ds W31 -0 .4 1 ' 4 -5 '-d s W32 -0 .4 0 ' W33 28'-cov (prob. lg l y t ) 5' Table B1 ( c o n t ' d . ) . S ite No. W42 -1 .5 9 ' MassShore­ "Recent" "Recent" V is ib le lin e Erosion Erosion Ground Movement O rienta­ At B l u f f At B l u f f Water On Slope Below Seepage Crest tio n Base Crest Generalized B lu f f S tra tig ra p h y B lu ff Height l O ' - t / 3'-ws / 2 ' - c l / 23V-cov / 1 7 V -t 56' N3%°W Yes Yes Yes Yes Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 MANITOWOC COUNTY W43 -1 .3 3 ' 2 V - t / 2V -w s / 5 ' - c l / 35'-cov 45' N4%°E Yes Yes Yes Yes W44 -0 .7 6 ' 17'-ws / 1 3 '- t / 14'-cov 44' N12°E Yes Yes Yes Yes W45 -0 .7 4 ' 14'-cov ( p a r t ly ws) / l O ' - t / 16'-ws 40' N35°E No No No Yes (o ld ) W46 -0 .4 0 ' 3 '- c l / lO'-ws / 15'- c l / 17'-cov (prob. l g l y t ) 45' N5°E Yes Yes Yes Yes W47 -0.27' 17'-ws / 10 ' - c l / 2 0 '-cov (prob. l g l y t ) 47' N15°E Yes Yes Yes Yes W48 -0 .1 7 ' 5V-ws / 6 '-ws w/ abun. pebbles & cobbles / 1 6 '- t 27%' N23%°E Yes Yes Yes Yes W49 -0 .7 3 ' 6 '-ws / 8 ' - t / 6 '-ws w/ abun. pebbles & cobbles / 2 0 ' -ws / 55' N: N18°E S: N37°E Yes Yes Yes Yes 15'-cov Table B1 S ite No. (cont'd.). Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 Generalized B lu ff S t r a t i graphy B lu ff Height MassShore­ "Recent" "Recent" V is ib le Ground Movement Erosion Erosion lin e O rienta­ At B lu f f At B l u f f Water On Slope Below Seepage Base Crest t io n Crest N: N17°W S: N%°W Yes Yes No Yes 8' N48%°E Yes Yes No Yes 3 '- c l / lO '-cov 13' N22°W Yes Yes No Yes -1 .7 7 ' 20' - t 20' N3°W Yes Yes No Yes -0 .8 0 ' 4'-ws / 5 ' - t / 9'-ws / 3*- c l / 8 ' -cov (prob. c l) 29' N15^°E Yes Yes Yes Yes W50 -1 .0 6 ' 9'-ws / 7'-cov (prob. ws) W51 -1 .6 7 ' 7'-ws / l ' - t W52 -2 .6 3 ' W53 W54 16' KEWAUNEE COUNTY U55 -0 .9 0 ' 9 ' - t / 15'-ws / lO '-cov / 9 ' - t / 14'-cov 57' N17°E Yes Yes Yes Yes W56 -1 .2 9 ' 5 ' - t / 20'-ws / 30'-cov (prob. ws w/ abun. pebbles) 55' N23°E Yes Yes Yes Yes W57 -0 .7 7 ' 7*- t / 4'-ws / 2 0 '- t / 9 '-cov 40' N11°E Yes Yes Yes Yes W58 -0 .2 5 ' 5 ' - t / 33'-cov / lO'-ws 48' N19°E Yes Minor No Yes W59 -0 .2 4 ' 9 ' - t / 1 '- c l / 35'-ws ( l g l y pebbles & cobbles 45' N: N5°E S: N19°E Yes No No Yes Table B1 ( e o n t ' d . ). S ite No. Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 Generalized B lu ff S tra tig ra p h y W60 - 0 .22' 5 ' - 1 / 17' -ws / 4 0 '-cov W61 +0.08' 2 ' -ws B lu ff Height MassShore­ "Recent" "Recent" V is ib le Erosion Erosion Ground Movement lin e O rienta­ At B lu f f At B l u f f Water On Slope Below Seepage Crest tio n Base Crest 62' N15°E Yes No No Yes 2' N23°E Minor Minor No Yes N: N25^°E Minor S: N12^°E Minor No Yes DOOR COUNTY W62 -0 .1 7 ' l ' - d s / 3 -ws 4' Table B1 ( c o n t ' d . ). Footnotes " F i l l m aterial had re c e n tly been deposited lakeward o f the natural b l u f f l i n e , a r t i f i c i a l l y extending the b l u f f c re s t by 4.5 fe e t as o f August 16, 1976. The resurvey was terminated a t a point co in cid in g w ith the natural b l u f f lin e p o s itio n . bF i l l m aterial had been deposited lakeward o f the natural b l u f f l i n e , a r t i f i c i a l l y extending the b l u f f cre st by 15 fe e t as o f Ju ly 3, 1976. In d ica tio n s are th a t t h is f i l l i n g process w i l l continue. The resurvey was terminated at a p o in t c o in c id in g w ith the natural b l u f f lin e p o s itio n . ‘ Recession values f o r most s ite s in Racine County are in c o n s is te n t w ith those published by Powers (1958) and the U.S. Corps o f Engineers (1953); t o t a l long-term losses c ite d in these old e r references were g enerally greater than the to t a l b l u f f lin e r e tr e a t determined in t h is study. Upon examination o f the techniques and data employed by Powers and the Corps i t is believed th a t the values in th is present study are the c o rre c t ones. Resurveys during t h is in v e s tig a tio n u t i l i z e d R.L.S. survey maps, dossiers on section and q u a rte r-se ctio n loca tio n s and p u b lica tio n s generated by a recent and ongoing land survey remonumentation program (Southeastern Wisconsin Regional Planning Commission, 1968). dDuring the present high lake stage but subsequent to "recent" erosion at the b l u f f cre st a seawall had been constructed at the b l u f f base. “Although there was minor or no "recent" erosion a t the b l u f f base and cre st at the section lin e the b l u f f has been s i g n if ic a n t l y eroding a short distance to the north. *A municipal groin system extends approximately o n e - f if t h o f a m ile north and south o f the section lin e and appears to be p ro te ctin g the b l u f f very w e ll; the beach zone is r e l a t i v e l y wide here. Adjacent and south o f the groin system the b l u f f has been experiencing severe erosion. 9Erosion a t the b l u f f crest at the section lin e was caused by lo c a liz e d slumping a short time p r io r to the resurvey. Table B1 ( c o n t ' d . ) . hB l u f f erosion and recession appear more severe at t h i s s it e than the low recession rate in d ic a te s . Because the monument at the SW Corner / Section 33 / T11N,R22E could not be located the resurvey to the b l u f f c re s t was run from the more d is ta n t NW Corner / Section 3 / T10N,R22E. This d eviation from the normal procedure may have introduced some e rro r in to the calculated r e tr e a t value. ‘ The section lin e coincides w ith the north fa c in g , southern v a lle y slope o f Sevenmile Creek. Several yards south o f the section lin e the lake b l u f f ris e s to a height o f 37 fe e t. Table B2. Selected c h a ra c te ris tic s o f the Michigan study s ite s . Key To The Table B l u f f S tratigraphy ds: Dune sand; eolian deposits o f sand size p a r tic le s . ws: W ate r-la id sand; water-deposited sand size p a r t ic le s , w ith and w ithout pebbles, and to include t h in interbedded zones w ith high percentage o f cla y o r s i l t size p a r t ic le s . c l: Clay; water-deposited sediments o f a clay or s i l t y - c l a y te x tu re . t: fd : Covered; the b l u f f s tra tig ra p h y is obscured by overburden. Foredune; the sand dune immediately behind the backshore and fro n tin g the primary b l u f f . This feature tends to be ephemeral; during higher water periods i t g enerally undergoes erosion while during lower lake elevations i t tends to undergo a ccretion. prev. fd : Previous foredune; a foredune was present at the beginning o f the present high water period in 1968 but had eroded completely by 1976-77. remn. fd : Remnant o f a foredune; only the very la s t p o rtio n o f a foredune remains and t h is may be spaced in t e r m it t a n t ly along the lakeshore segment between points where b l u f f toe erosion has begun. "Recent Erosion" "Recent" r e fe r s to any time during the present high lake stage (since 1968). 158 cov: T i l l ; n o n - s t r a t if ie d , non-sorted g l a c i a l l y deposited sediments which at the study s ite s are normally o f a cla y loam te x tu re and which usually include pebbles and/or cobbles. Table B2 ( c o n t ' d . ) . S ite No. Generalized B lu ff S tra tig ra p h y Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 B lu ff Height MassShore­ "Recent" "Recent" V is ib le Erosion Erosion Ground Movement lin e O rienta­ At B lu f f At B l u f f Water On Slope Below Seepage Crest Base tio n Crest BERRIEN COUNTY M1 - 1. 88' 58'-ws 58' N25°E Yes Yes No Yes M 2° -2 .1 6 ' 7V-ws / 12%'- t / 5'-ws / 4 1- 1 / 31 '-ws / 15'-cov 73' N24%°E Yes Yes Yes Yes M3 -1 .2 4 ' lO'-ws / 3 6 '- t / 62'-ws 108' N38°E Yes Yes Yes Yes M 4b -4 .3 0 ' 1 2 -1 5 '-t / 85-95'-ws 1 10 ' N35°E Yes Yes Yes Yes M5 -2 .9 2 ' 5'-ws / 5 4 '- t / 5 1 '-ws 110' N37°E Yes No Yes Yes M6 -2 .3 9 ' 7'-ws / +33'- t / +31'-ws / w/ remn. fd 71' N35°E Yes No Yes Yes VAN BUREN COUNTY M7 -1 .5 3 ' 19'-ws / 16'- c l 35' N: N13°E S: N22°E Yes Yes Yes Yes M8 -2 .6 9 ' 6 '-ws / 41' N: N15°E S: N28°E Yes Yes Yes Yes 3 5 '- t T able B2 ( c o n t ' d . ). S ite No. Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 Generalized B lu ff S tra tig ra p h y B lu ff Height MassShore- "Recent" "Recent" V is ib le Ground Movement lin e Erosion Erosion O rienta­ At B l u f f At B l u f f Water On Slope Below Seepage Crest Base tio n Crest ALLEGAN COUNTY M9 -1 .3 4 ' 9'-ws / 1 2 1- c l / 51'-ws 72' N: N9°E S: N15°E Yes Yes Yes Yes M10 -1 .5 4 ' 2 0 '-ws / 9 ' - t / 15'-ws / 2 5 '- t 69' N6 °E Yes No Yes Yes M il -0 .9 3 ' 7' -ws / 4 8 '- t ‘ 55' N5°E Yes Yes Yes Yes M12d -0 .9 2 ' 7 '-d s 7' N11°E Yes Yes No Yes M13 -0 .9 4 ' 7 ' -ws / 2 8 '- t / lO'-ws 45' N6 °W Yes Yes Yes Yes M14 -0 .9 3 ' 19'-ws / 4 8 ' - t / prev. fd 67' N: N11°E_ S: N3Jg°E Yes No Yes Yes Yes Yes No Yes OTTAWA COUNTY M15 -0 .8 0 ' 2 '-ds / 28'-ws 30' Due N prev. fd M16 - 0 .22' 10-15'-ds / 10-15'-ws prev. fd 28' N1%°W Yes Yes No Yes M17 -1 .0 3 ' 29 '-ds 29' N2°E Yes Yes No Yes Table B2 ( c o n t ' d . ) . S ite No. Generalized B lu ff S tra tig ra p h y Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 B lu ff Height MassShore­ "Recent" "Recent" V is ib le Erosion Erosion Ground Movement lin e O rienta­ At B lu f f At B l u f f Water On Slope Below Seepage Crest tio n Base Crest M18 -0 .6 9 ' 3 ' - ds / 4 0 '-ws / prev. fd 43' N2°E Yes Yes No Yes M19* -0 .7 9 ' 3 6 '-ds / 24'-ws / w/ 2 fd 60' N9°W Yes No No Yes M20 -0 .3 8 ' 50'-ds / prev. fd 50' N6 °W Yes Yes No Yes M21* +0.27' 17'-ds / prev. fd 17' N6 °W Yes Yes No Yes M229 - 1.00' 5 '-d s / lO '-ds or ws? / 8 '-ws / / prev. fd 29' N7°W Yes Yes No Yes 42'-ds 23%'-ds 42' 23%' N13°W Yes No Yes No No Yes 75' N26%°W Yes Yes No Yes 6'- t M23h -0 .3 6 ' +0.06' MUSKEGON COUNTY M24 -2 .1 7 ' lO '-ds / 40'-cov (prob. ds & ws) / 2 5 '-ws / prev. fd Table B2 ( c o n t ' d . ). S ite No. Aver. Ann. B l u f f Crest Change 6L0 Date To 1976-77 Generalized B lu ff S tratigraphy B lu ff Height Shore­ "Recent" "Recent" V is ib le MassGround Movement lin e Erosion Erosion O rienta­ At B l u f f At B l u f f Water On Slope Crest tio n Base Seepage Below Crest M25 -0 .7 4 ' 3'-ds / 2 9 '-ws 32' N24VW Yes Yes No Yes M26* -1 .0 6 ' ?'-ds / ?1-ws / w/ remn. fd 40' N26°W Yes No No No M27 -1 .3 9 ' 40'-ws / prev. fd 40' N24°W Minor No' No No M28 -1 .5 9 ' 481-ds / 58'-ws / prev. fd 106' N20°W Yes No No Yes M29 -1 .4 5 ' 16'-ws / 2 ' - t / 6 5 '-ws 83' N15°W Yes Yes No Yes M30 -1 .3 5 ' 2 0 '-ds / 20' N13?s0W Yes Yes No Yes prev. fd OCEANA COUNTY M31h -0 .4 7 ' 0 .00' 36 '-ds 18'-ds 36' 18' N13°W Yes No Yes No No Yes M32 +0.31' 25'-ds / prev. fd 25' N20°W Yes Yes No Yes M33 -2 .2 4 ' 16'-ds / prev. fd 16' N13°W Yes Yes No Yes Table B2 ( c o n t ' d . ). S ite No. M34 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 - 0 . 11 ' Generalized B lu ff S tra tig ra p h y 1 2 '-ds / B lu f f Height MassShore- "Recent" "Recent" V is ib le Ground Movement Erosion Erosion lin e O rienta­ At B lu f f At B l u f f Water On Slope Below Crest Seepage Base t io n Crest 12' N2°W Yes Yes No Yes prev. fd M35 -1 .9 9 ' 15'-ds / prev. fd 15' N5°W Yes Yes No Yes M36h -0 .3 4 ' +0.77' 37'-ds 1 5 '- ds 37' 15' N7°E Yes No Yes No No Yes 65'-ws / 100 ' - t 165' N14°W Yes No Yes Yes 114'-ws / 2 3 '- cl / 1 2 '-cov / 170' N2°W Yes Yes Yes Yes MASON COUNTY M37 -0 .8 0 ' M38 -0 .6 5 ' 1 2 '-ws M39 +0.70' 16’ -ds 16' N30°W Yes Yes No Yes M40 +0.76' 15'-ds 15' N: N35°E S: N27J#E Yes Yes No Yes N35°E Yes Yes No Yes MANISTEE COUNTY M41 -0 .9 7 ' 8 '-ds / prev. fd 8' Table B2 ( c o n t ' d . ). Generalized B lu ff S tra tig ra p h y B lu ff Height MassShore- "Recent" "Recent" V is ib le Ground Movement Erosion Erosion lin e O rienta­ At B lu f f At B l u f f Water On Slope Below Seepage Crest tio n Base Crest S ite No. Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 M42 -0 .5 2 ' 29'-ds / w/ fd 29' N16°E Yes No No Yes M43 -1 .9 1 ' 15'- t / 27'-cov (prob. ws) / 26'-ws 68' M20°E Yes Yes No Yes M44 -2.61* 16'- t / 4 6 '-ws 62' N16%°E Yes Yes No Yes M45 -0 .9 9 ' 2 - 1 0 '- t / 10-40'-ws / 1 0 -4 0 '-t / w/ remn. fd 78' N18^°E No to S Ii ght No No No M46 -0 .8 0 ' lO '-ds / prev. fd 10' N22^°E Yes Yes No Yes M47 - 1. 10' 16'-ds / prev. fd 16' N27°E Yes Yes No Yes M48 -1 .7 4 ' 6 '-ds 6' N35°E Yes Yes No Yes M49 -0 .8 5 ' 2 6 '- ds / prev. fd 26' N17°E Yes No No Yes (poss. ws) Table B2 ( c o n t ' d . ). S ite No. Generalized B lu ff S tra tig ra p h y Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 B lu ff Height MassShore­ "Recent" "Recent" V is ib le Ground Movement lin e Erosion Erosion O rienta­ At B l u f f At B l u f f Water On Slope Below Seepage Crest tio n Base Crest BENZIE COUNTY M50 -2 .6 2 ' 1 0 -1 5 '-ds / 6 - 1 0 '- t / 125-1501-ws/ l O ' - t / 2V-ws / l V - t / 3 '- c l / 6 '-ws / 2 ' - c l / 151- t / 3 5 '-ws / 1 8 '- t / 2 *- c l / 6 ' -cov / 16'-ws / 2 5 '- t 310' n i i °w Yes No Yes Yes LEELANAU COUNTY M51 -0 .0 6 ' 1 3 '-ds / prev. fd 13' N4°E Yes Yes No Yes M52 -0 .3 4 ' 1 5 '-ds / w/ remn. fd 15' N4°W Yes No No Yes M53h -0 .2 7 ' +0.29' 14'-ds 7' -ds 14' 7' N17°E Yes Yes No Yes No No Yes M54 -0 .3 9 ' 30' - t / w/ remn. fd & ds veneering slope 30' No No No M55 -1 .5 2 ' 4 1 '- t / 6 3 '-ws M56 -0 .0 3 ' 8 '-ds / prev. fd 104' 8' Yes N: niWE S: N22°E (on fd) N5°E Yes No No Yes W: N37°W E: N87°W Minor Minor No Yes Table B2 ( c o n t ' d . ). Footnotes "The b l u f f was receding r a p id ly u n t il 1971 at which time a m u lt i- m illio n d o lla r steel p i le and limestone block revetment and groin system was constructed northward from a p o in t j u s t south o f th is section l in e in order to p rote ct highway and r a ilr o a d rig h ts -o f-w a y . B l u f f recession has been minimal since 1971. bThe section lin e in te rs e c ts the b l u f f cre st at an acute angle and at a point where a very large slump and some g u lly in g have occurred. Although b l u f f erosion and recession have been s ig n if ic a n t along t h is reach o f the shorezone the long-term recession rate f o r t h is s it e is probably somewhat higher than is representative o f the reach as a whole. eThis t i l l includes large pockets and zones o f sand and/or gravel in the lower 20 fe e t. dThe section lin e coincides w ith the northern slope o f a ravine through which in te r m it t a n t grainage flow s. Except fo r a small cut the ravine mouth is blocked by low dunes; the resurvey measurement terminated at the lakeward cre st o f these dunes. To the north and south b lu f f s r is e 43 to 50 fe e t and are composed o f sand o v e rlyin g t i l l . *Because o f the rounded nature o f the cre st and pedestrian t r a f f i c , the p o s itio n o f the b l u f f li n e is somewhat ambiguous. Although re s u lts o f t h is resurvey in d ica te d long-term net accertion comparison w ith a R.L.S. property survey in d ica te d a b l u f f c re s t loss o f 8 .8 fe e t between 1974 and 1976. 9The resurvey measurement was c a rrie d to a li n e connecting the b l u f f cre st on e ith e r side o f the section lin e easement. The b l u f f at the easement was notched in 1973 when a drainage pipe was in s ta lle d . hAt four dune s ite s (M23, M31, M36, and M53) two d i s t i n c t b l u f f crests lakeward cre st is a b l u f f li n e o f a lo w e r - r e lie f dune te rra ce which fro n ts the somewhat h i g h e r - r e l ie f dune fe a tu re . Because o f the s itu a tio n and the lack o f i t was not possible p o s it iv e ly to ascertain to which p o in t the GLO measurement t h is study's measurements were ca rrie d to each o f the two possible cre st lin e s are recognized. The more landward cre st o f a c l a r i t y in the GLO notes terminated; consequently, and corresponding recession Table B2 ( c o n t 1d . ). rates then determined. In the ta b le the upper fig u re pertains to measurements to the cre st l in e o f the somewhat h i g h e r - r e l ie f landward dune form and the lower fig u re to measurements to the b l u f f l in e o f the lo w e r - r e lie f lakeward dune fe a tu re . In three o f the four cases measurements to e ith e r cre st indicated r e l a t i v e l y small changes in b l u f f lin e p o sitio n r e la t iv e to the GLO surveys. The recession or accretion rates determined fo r the four s ite s are not included in any o f the q u a n tita tiv e analysis performed in th is study. In no way does t h is exclusion a f f e c t any o f the conclusions reached and, in f a c t , t h e i r in clu sio n would only increase support f o r the fin d in g s reported. 'During the high lake period o f the e a rly 1950's the water level was up present b l u f f . However, during the low lake stage in the la te 1950's and e a rly three to nine fe e t in height and a t le a s t 65 to 75 fe e t in width had formed in t h is foredune has la r g e ly been removed by wave erosion during the present high against the base o f the 1960's a foredune terrace f r o n t o f the present b l u f f ; water period. A lthough there has been only minor "recent" erosion at the b l u f f cre st at the section lin e lo c a tio n erosion has reached the cre st several hundred fe e t to the north and south. APPENDIX C LONG-TERM BLUFF LINE CHANGES AND LOCATIONS OF THE WISCONSIN AND MICHIGAN STUDY SITES Long-term b l u f f l in e changes and lo ca tio n s o f the Wisconsin study s ite s are described in Table Cl and those o f the Michigan s ite s are displayed in Table C2. 168 Table Cl. Long-term b l u f f l in e changes and lo c a tio n s o f the Wisconsin study s ite s . S ite No. Section Line Location Year Resur­ vey: of This GLO Survey Study Poi nt of Survey O rigin GLO Distance To "Meander Line" B l u f f Crest 1976-77 Change Distance GLO Date To B l u f f Crest To 1976-77 Aver. Ann. B lu f f Crest Change GLO Date To 1976-77 KENOSHA COUNTY W1 South Line/Sec 29/T1N.R23E 1835 1976 SW Cor 2591,82' (789.99 m) 1525.50' (464.97 m) -1066.32' (-325.01 m) -7 .5 6 ' (-2.304 m) W2 South Line/Sec 20/T1N.R23E 1835 1976 SW Cor 1639.44' (499.70 m) 657.00' (200.25 m) - 982.44' (-299.45 m) -6 .9 7 ' (-2.124 m) W3 South Line/Sec 17/T1N,R23E 1835 1976 SW Cor 1268.52' (386.64 m) 376.00' (114.60 m) - 892.52' (-272.04 m) -6 .3 3 ' (-1.929 m) W4 South Line/Sec 8/TlN»R23E 1835 1976 SW Cor 975.48' (297.33 m) 630.00' (192.02 m) - 345.58' (-105.33 m) -2 45 1 (-0.747 m) W5 South Line/Sec 7/T2NsR23E 1836 1976 Sk Cor 2950.86' (899.42 m) 2566.94' (782.40 m) - 383.92' (-117.02 m) -2 .7 4 ' (-0.835 m) W 6b South Line/Sec 5/T2N,R23E 1836 1976 SW Cor 1581.36' (482.00 m) 1241.67' (378.46 m) - 339.69' (-103.54 m) -2 43' (-0.741 m) 1835 1976 S% Cor 435.60' (132.77 m) 91.80' ( 27.98 m) - 343.80' (-104.79 m) -2 .4 4 ' (-0.744 m) RACINE COUNTY* W 7d South Line/Sec 32/T3N.R23E Table Cl ( c o n t 1d . ). S ite No. Section Line Location Year Resur­ of vey: This GLO Survey Study Point of Survey O rigin GLO Distance To "Meander Line" B l u f f Crest 1976-77 Change Distance GLO Date To B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 W8 North Line/Sec 4/T3N»R23E 1835 1976 N% Cor 1849.98' (563.87 m) 1729.48' (527.15 m) - 120.50' ( - 36.73 m) -0 .8 5 ' (-0.259 m) W9 South Line/Sec 27/T4N,R23E 1836 1976 SW Cor 1058.64' (322.67 m) 926.50' (282.40 m) - 132.14' (- 40.28 m) -0 .9 4 ' (-0.287 m) W10 South Line/Sec 16/T4NSR23E 1836 1976 S% Cor 1028.28' (313.42 m) 766.12' (233.51 m) - 262.16' ( - 81.13 m) -1 .8 7 ' (-0.570 m) WU South Line/Sec 8/T4N.R23E 1836 1976 S% Cor 1081.08' (329.51 m ) 907.20' (276.51 m) - 173.88' ( - 53.00 m) -1 .2 4 ' (-0.378 m) W12 South Line/Sec 6/T4N,R23E 1836 1976 Sk Cor 2288.88' (697.65 m) 2041.17' (622.15 m) - 247.71' ( - 75.50 m) -1 .7 7 ' (-0.539 m) MILWAUKEE COUNTY W13 South Line/Sec 25/T5N,R22E 1836 1976 S% Cor 2747.25' (837.36 m) 2286.54' (696.94 m) - 460.71' (-140.42 m) -3 .2 9 ' (-1.003 m) W14 South Line/Sec 36/T6NsR22E 1836 1976 SW Cor 1049.40' (319.86 m) 904.30' (275.63 m) - 145.10' (- 44.23 m) -1 .0 4 ' (-0.317 m) W15 South Line/Sec 25/T6N,R22E 1836 1976 SW Cor 1822.92' (555.63 m) 1732.30' (528.01 m) - 90.62' ( - 27.62 m) -0 .6 5 ' (-0.198 m) Table Cl ( c o n t ' d . ). S ite No. Section Line Location W16* South Line/Sec 24/T6N.R22E Year Resur­ of vey: This GLO Survey Study Point of Survey O rigin GLO Distance To "Meander Line" 1836 1976 SW Cor 1273.14' (388.05 m) 1976-77 B l u f f Crest Di stance Change GLO Date To B lu f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 1160.40' (353.69 m) - 112.74' (- 34.36 m) -0 .8 1 ' (-0.247 m) OZAUKEE COUNTY W17 South Line/Sec 33/T9N.R22E 1833 1976 Sk Cor 462.00' (140.82 m) 443.66' (135.23 m) (- 18.34' 5.59 m) -0 .1 3 ' (-0.040 m) W18 South Line/Sec 21/T9N,R22E 1835 1977 SW Cor 686.40' (209.21 m) 406.00' (123.75 m) - 280.40' (- 85.47 m) -1 .9 7 ' (-0.600 m) W19 South Line/Sec 17/T9N,R22E 1835 1977 S% Cor 1132.56' (345.20 ra) 800.80' (244.08 m) - 331.76' ( - 101.12 m) -2 34' (-0.713 m) W20 South Line/Sec 8/T9N.R22E 1835 1976 Sh Cor 775.50' (236.37 m) 413.00' (125.88 m) - 362.50' (-110.49 m) -2 .5 7 ' (-0.783 m) W21 South Line/Sec 5/T9N,R22E 1835 1976 S% Cor 1912.68' (582.98 m) 1552.43' (473.18 m) - 360.25' (-109.80 m) -2 .5 5 ' (-0.777 m) W22 South Line/Sec 33/T10N,R22E 1833 1976 SW Cor 550.44' (167.77 m) 135.50' ( 41.30 m) - 414.94' (-126.47 m) -2 .9 0 ' (-0.884 m) W23 South Line/Sec 28/T10N,R22E 1835 1977 SW Cor 2524.50' (769.47 m) 2157.55' (657.62 m) - 366.95' (-111.85 tn) -2 .5 8 ' (-0.786 m) Table Cl ( c o n t ' d . ) . 1976-77 B l u f f Crest Change Distance To GLO Date B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 Point of Survey O rigin GLO Distance To "Meander Line" 1977 Sk Cor 2640.00' (804.67 m) 2222.41' (677.39 m) - 417.59' (-127.28 m) -2 .9 4 ' (-0.896 m) 1835 1976 SW Cor 429.00' (130.76 m) 225.50' ( 68.73 m) - 203.50' ( - 62.03 m) -1.44' (-0.439 m) 1833 1977 NW Cor 2315.28' (705.70 m) 2256.40' (687.75 m) - 58.88' (- 17.95 m) -0 .4 1 ' (-0.125 m) South Line/Sec 25/T12N,R22E 1835 1976 Sk Cor 2188.56' (667.07 m) 2171.23' (661.79 m) (- 17.33' 5.28 m) - 0 . 12' (-0.037 m) W28 South Line/Sec 18/T12N.R23E 1835 1976 SW Cor 1942.38' (592.04 m) 1913.78' (583.32 m) (- 28.60' 8.72 m) - 0.20' (-0.061 m) Year Resur­ vey: of This GLO Survey Study S ite No. Section Line Location W24 South Line/Sec 16/T10N,R22E 1835 W25 South Line/Sec 10/T10NSR22E W26f North Line/Sec 3/T10N.R22E W27 SHEBOYGAN COUNTY W29 South Line/Sec 31/T13N,R23E 1834 1976 SW Cor 2409.00' (734.26 m) 2376.35' (724.31 m) (- 32.65' 9.95 m) -0 .2 3 ' (-0.070 m) W30 South Line/Sec 30/T13N.R23E 1835 1976 SW Cor 2230.14' (679.75 m) 2282.41' (695.68 m) + 52.27' (+ 15.93 m) +0.37' (+0.113 m) W31 South Line/Sec 17/T13NSR23E 1835 1976 SW Cor 1261.92' (384.63 m) 1203.69' (366.88 m) - 58.23' ( - 17.75 m) -0 .4 1 ' (-0.125 m) Table Cl ( c o n t ' d . ) . S ite No. Section Line Location W32 South Line/Sec 8/T13N,R23E Year Resur­ vey: of This GLO Survey Study 1835 1976 1976-77 B l u f f Crest Change Distance GLO Date To B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 Poi nt of Survey O rigin GLO Distance To "Meander Li ne" SW Cor 1397.22' (425.87 m) 1340.89' (408.70 m) - 56.33' ( - 17.17 m) ( - 0 .1 2 2 m) -0 .4 0 ' W33 South Line/Sec 4/T13N,R23E 1835 1976 SW Cor 1712.70' (522.03 m) 1610.85' (490.99 m) - 101.85' (- 31.04 m) -0 .7 2 ' (-0.219 m) W34 South Line/Sec 27/T14N,R23E 1835 1976 SW Cor 2022.90' (616.58 m) 2029.21' (618.50 m) + (+ 6.45' 1.97 m) +0.05' (+0.015 m) W35 South Line/Sec 14/T14N,R23E 1835 1976 SW Cor 2279.64' (694.83 m) 2287.76' (697.31 m) + (+ 8. 12' 2.47 m) +0.06' (+0.018 m) W36 South Line/Sec 2/T14N.R23E 1835 1976 Sk Cor 2072.40' (631.67 m) 1918.93' (584.89 m) - 153.47' (- 46.78 m) -1 .0 9 ' (-0.332 m) W37 North Line/Sec 3/T15N.R23E 1834 1977 N% Cor 1687.62' (514.39 m) 1535.00' (467.87 m) - 152.65’ (- 46.53 m) -1 .0 7 ' (-0.326 m) W38 South Line/Sec 27/T16N.R23E 1835 1976 SW Cor 3379.20s (1029.98 m) 3233.50' (985.57 m) - 145.70' ( - 44.41 m) -1 .0 3 ' (-0.314 m) W39 South Line/Sec 22/T16N,R23E 1835 1976 SW Cor 2942.28' (896.81 m) 2813.20' (857.46 m) - 129.08' ( - 39.34 m) -0 .9 2 ' (-0.280 m) W40 South Line/Sec 15/T16N,R23E 1835 1976 SW Cor 3411.54' (1039.84 m) 3255.74' (992.35 m) - 155.80' (- 47.49 m) - 1 . 10' (-0.335 m) Table Cl ( c o n t ' d . ). B l u f f Crest 1976-77 Change Distance GLO Date To B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 1979.50' (603.35 m) - 150.98' (- 46.02 m) -1 .0 7 ' (-0.326 m) 1469.16' (447.80 m) 1243.50' (379.12 m) - 225.66' ( - 68.78 m) -1 .5 9 ' (-0.485 m) S% Cor 1370.82' (417.83 m) 1181.90' (360.24 m) - 188.92' (- 57.58 m) -1 33' (-0.405 m) 1976 SW Cor 646.14' (196.94 m) 538.27' (164.06 m) - 107.87' ( - 32.88 m) -0 .7 6 ' (-0.232 m) 1834 1976 S% Cor 660.00' (201.17 m ) 555.22' (169.23 m) - 104.78' ( - 31.94 m) -0 .7 4 ' (-0.226 m) 1834 1977 SW Cor 891.00' (271.58 m) 834.20' (254.26 m) - 56.80' (- 17.31 m) -0 .4 0 ' ( - 0 .1 2 1 m) Point of Survey O rigin GLO Distance To "Meander Line" 1976 SW Cor 2130.48' (649.37 m) 1835 1977 SW Cor South Line/Sec 27/T17N.R23E 1834 1976 W449 South Line/Sec 14/T17N,R23E 1834 W459 South Line/Sec 11/T17N,R23E South Line/Sec 36/T18N,R23E Year Resur­ vey: of This GLO Survey Stidy S ite No. Section Line Location W41 South Line/Sec 10/T16N,R23E 1835 W42 South Line/Sec 3/T16N,R23E MANITOWOC COUNTY W43 W46 W47 South Line/Sec 24/T18N,R23E 1834 1976 Wl/16 Cor 2170.74' (661.64 m) 2132.68' (650.04 m) - 38.06' ( - 11.60 m) -0 .2 7 ' (-0.082 m) W48 South Line/Sec 13/T18N.R23E 1834 1976 El/16 Cor 1234.20' (376.18 m) 1209.67' (368.71 m) (- -0 .1 7 ' (-0.052 m) 24.53' 7.48 m) Table Cl ( c o n t ' d . ) . Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 1064.50' (324.46 m) - 103.70' (- 31.61 m) -0 .7 3 ' (-0.223 m) 1907.40' (581.38 m) 1756.58' (535.41 m) - 150.82' ( - 45.97 m) -1 .0 6 ' (-0.323 m) SW Cor 891.00' (271.58 m) 655.30' (199.74 m) - 235.70' (- 71.84 m) -1 .6 7 ' (-0.509 m) 1976 SW Cor 1905.42' (580.77 m) 1532.18' (467.01 m) - 373.24' (-113.76 m) -2 .6 3 ' (-0.802 m) GLO Distance To "Meander Line" 1976 SW Cor 1168.20' (356.07 m) 1834 1976 SW Cor 1835 1976 1834 Section Line Location W49 South Line/Sec 5/T18N,R24E 1834 W50 South Line/Sec 32/T19N,R24E W51 West Line/Sec 10/T19N,R24E W52h South Line/Sec 13/T21n,R24E 1976-77 B l u f f Crest Change Di stance To GLO Date B l u f f Crest To 1976-77 Point of Survey O rigin Year Resur­ vey: of This GLO Survey Study S ite No. W53 South Line/Sec 2/T21N,R24E 1834 1976 S% Cor 2188.56’ (567.07 m) 1937.55' (590.57 m) - 251.01' ( - 76.51 m) -1 .7 7 ' (-0.539 m) W54 North Line/Sec 2/T21N,R24E 1834 1976 N% Cor 2502.06' (762.63 m) 2387.96' (727.85 m) - 114.10' (- 34.78 m) -0 .8 0 ' (-0.244 m) 1835 1976 SW Cor 660.00' (201.17 m) 533.44' (162.59 m) - 126.56' ( - 38.58 m) -0 .9 0 ' (-0.274 m) 1834 1976 SW Cor 2377.32' (724.61 m) 2194.26' (668.81 m) - 183.06' (- 55.80 m) -1 .2 9 ' (-0.393 m) KEWAUNEE COUNTY W55 South Line/Sec 18/T22N,R25E W5(f South Line/Sec 8/T23N,R25E Table Cl ( c o n t ' d . ) . S ite No. Section Line Location Year Resur­ vey: of This GLO Survey Study Point of Survey O rigin GLO Distance To "Meander Line" 1976-77 B l u f f Crest Di stance Change GLO Date To B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 1834 1976 Sk Cor 827.64' (252.26 m) 718.38' (218.96 m) - 109.26' (- 33.30 m) -0 .7 7 ' (-0.235 m) South Line/Sec 29/T24N,R25E 1834 1976 SW Cor 4884.00' (1488.64 m) 4884.00' (1477.91 m) - 35.21' ( - 10.73 m) -0 .2 5 ' (-0.076 m) W59h South Line/Sec 21/T24N,R25E 1834 1976 SW Cor 1653.30' (503.93 m) 1618.96' (493.46 m) - 34.34' ( - 10.47 m) -0 .2 4 ' (-0.073 m) W60h South Line/Sec 16/T24N.R25E 1834 1976 SW Cor 2373.36' (723.40 m) 2342.00' (713.84 m) (- 31.36' 9.56 m) - 0 .22' (-0.067 m) 1834 1976 Wl/16 Cor 2319.90' (707.11 m) 2331.34' (710.59 m) + (+ 11.40' 3.47 m) +0.08' (+0.024 m) 1835 1976 Sk Cor 2593.80' (790.59 m) 2570.30' (783.43 m) (- 23.50' 7.16 m) -0 .1 7 ' (-0.052 m) W57h South Line/Sec 5/T23N.R25E W58 W61 North Line/Sec 3/T24N,R25E DOOR COUNTY W62 South Line/Sec 4/T26N,R26E Table Cl ( c o n t ' d . ) . Footnotes “ F i l l m aterial had re c e n tly been deposited lakeward o f the natural b l u f f l i n e , a r t i f i c i a l l y extending the b l u f f c re s t by 4.5 fe e t as o f August 16, 1976. The resurvey was terminated at a point co in cid in g w ith the natural b l u f f lin e p o s itio n . bF i11 m aterial had been deposited lakeward o f the natural b l u f f l i n e , a r t i f i c i a l l y extending the b l u f f cre st by 15 fe e t as o f July 3, 1976. In d ica tio n s are th a t t h is f i l l i n g process w i l l continue. The resurvey was terminated at a p o in t co in cid in g w ith the natural b l u f f lin e p o s itio n . ‘ Recession values f o r most s ite s in Racine County are in c o n s is te n t w ith those published by Powers (1958) and the U.S. Army Corps o f Engineers(1953); t o t a l long-term losses c ite d in these o ld e r references were g e nerally greater than the t o t a l b l u f f lin e re tre a t determined in th is study. Upon examination o f the techniques and data employed by Powers and the Corps i t is believed th a t the values in th is present study are the co rre ct ones. Resurveys during t h is in v e s tig a tio n u t i l i z e d R.L.S. survey maps, dossiers on section and q u a rte r-s e c tio n lo ca tio n s and p u b lic a tio n s generated by a recent and ongoing land survey remonumentation program (Southeastern Wisconsin Regional Planning Commission, 1968). dDuring the present high lake stage but subsequent to "recent" erosion at the b l u f f cre s t a seawall had been constructed at the b l u f f base. eA municipal groin system extends approximately o n e - f if t h o f a m ile north and south o f the section lin e and appears to be p ro te c tin g the b l u f f very w e ll; the beach zone is r e l a t i v e l y wide here. Adjacent and south o f the groin system the b l u f f is experiencing severe erosion. * B lu f f erosion and recession appear more severe at t h is s it e than the low recession rate in d ic a te s . Because the monument at the SW Corner / Section 33 / T11N,R22E could not be located the resurvey to the b l u f f cre st was run from the more d is ta n t NW Corner / Section 3 / T10N,R22E. This d eviation from the normal procedure may have introduced some e rro r in to the calculated re tre a t value. s The section lin e from the monumented section corner to the b l u f f cre st was determined by a due east magnetic compass bearing. Table Cl ( c o n t ' d . ) . hAlthough the section or q u a rte r-se ctio n corner was not v is u a lly monumented the resurvey most l i k e l y o rig in a te d from a p o in t w ith in plus or minus three fe e t o f the actual corner. The section lin e from the assumed corner to tbe b l u f f was determined by a due east magnetic compass bearing. Table C2. Long-term b l u f f l i n e changes and lo ca tio n s o f the Michigan study s ite s . S ite No. Section Line Location Year Resur­ of vey: GLO This Survey Study Point of Survey O rigin GLO Distance To "Meander Line" 1976-77 B l u f f Crest Distance Change GLO Date To B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 BERRIEN COUNTY M1 South Line/Sec 4/T5S,R19W 1829 1977 SE Cor 957.00' (291.69 m) 678.87' (206.92 m) - 278.13' ( - 84.77 m) -1 .8 8 ' (-0.573 m) M 2° North Line/Sec 3/T5S,R19W 1829 1977 W k Cor 1225.62' (373.57 m) 906.10' (276.18 m) - 319.52' ( - 97.39 m) -2 .1 6 ' (-0.658 m) M3 South Line/Sec 6/T4S,R18W 1830 1977 S% Cor 2013.00' (613.56 m) 1830.65' (557.98 m) - 182.35' ( - 55.58 m) -1 .2 4 ' (-0.378 m) M 4b North Line/Sec 6/T4S,R18W 1830 1977 NE Cor 1788.60' (545.17 m) 1156.78' (352.59 m) - 631.82' (-192.58 m) -4 .3 0 ' (-1.311 m) M5 South Line/Sec 29/T3S,R18W 1830 1977 SE Cor 2937.00' (895.20 m) 2507.10' (764.16 m) - 429.90' (-131.03 m) -2 .9 2 ' (-0.890 m) M6 South Line/Sec 21/T3S.R18W 1830 1977 Sk Cor 1650.00' (502.92 m) 1303.71' (397.37 m) - 346.29' (-105.55 m) -2 39' (-0.728 m) 1830 1977 Sk Cor 1188.00' (362.10 m) 962.79' (293.46 m) - 225.21' ( - 68.64 m) -1 53' (-0.466 m) VAN BUREN COUNTY M7 South Line/Sec 21/T1N.R17W Table C2 ( c o n t ' d . ) . S ite No. Section Line Location M8 South Line/Sec 9/T1S.R17W Year Resur­ vey: of This GLO Survey Study Point of Survey O rigin GLO Distance To "Meander Line" B l u f f Crest 1976-77 Change Di stance To GLO Date B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 1830 1977 SE Cor 995.94' (303.56 m) 600.90' (183.15 m) - 395.04' (-120.41 m) -2 .6 9 ' (-0.820 m) ALLEGAN COUNTY M9 South Line/Sec 12/T1N,R17W 1831 1977 SE Cor 1059.96' (323.08 m) 864.00' (263.35 m) - 195.96' (- 59.73 m) - 1 .34' (-0.408 m) M10 North Line/Sec 6/T1N.R16W 1831 1977 NE Cor 5040.42' (1536.32 m) 4816.17' (1467.97 m) - 224.25' (- 68.35 m) -1 54' (-0.469 m) M il South Line/Sec 19/T2N,R16W 1831 1977 Sk Cor 1051.38’ (320.46 m) 915.30' (278.98 m) - 136.08' ( - 41.48 m) -0 .9 3 ' (-0.283 m) M12* South Line/Sec 18/T2N,R16W 1831 1977 SE Cor 2742.30' (835.85 m) 2608.58' (795.10 m) - 133.72' ( - 40.76 m) -0.92* (-0.280 m) M13 South Line/Sec 29/T2N,R16W 1831 1977 Sk Cor 1618.32' (493.26 m) 1481.45' (451.55 tn) - 136.87' ( - 41.72 m) -0 .9 4 ' (-0.287 m) M14 South Line/Sec 17/T3N,R16W 1831 1977 S% Cor 2006.40' (611.55 m) 1871.28' (570.37 m) - 135.12' ( - 41.18 m) -0.93* (-0.283 m) Table C2 ( c o n t ' d . ). S ite No. Section Line Location Year Resur­ vey: of GLO This Survey Study Point of Survey O rigin GLO Distance To "Meander Line" 1976-77 B l u f f Crest Distance Change To GLO Date B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 OTTAWA COUNTY M15 South Line/Sec 16/T5N,R16W 1832 1977 Sk Cor 924.00' (281.64 m) 808.00' (246.28 m) - 116.00' ( - 35.36 m) -0 .8 0 ' (-0.243 m) M16 South Line/Sec 9/T5N,R16W ‘ 1832 1977 S% Cor 891.00' (271.58 m) 858.40' (261.64 m) (- 32.60' 9.94 m) -0 .2 2 ' (-0.067 m) M17 South Line/Sec 4/T5N,R16W 1832 1977 Sk Cor 778.80' (237.38 m) 629.50' (191.87 m) - 149.30' (- 45.51 m) -1 .0 3 ' (-0.314 m ) M18 South Line/Sec 33/T6N,R16W 1832 1977 Sk Cor 754.38' (229.94 m) 653.90' (199.31 m) - 100.48' ( - 30.63 m) -0 .6 9 ' (-0.210 m) MlSf1 South Line/Sec 28/T6N,R16W 1832 1977 Sk Cor 831.60' (253.47 m) 717.68' (218.75 m) - 113.92' (- 34.72 m) -0 .7 9 ' (-0.241 m) South Line/Sec 33/T7N,R16W 1832 1977 Sk Cor 1716.00' (523.04 m) 1660.22' (506.04 m) - 55.78' (- 17.00 m) -0 .3 8 ' (-0.116 m) M21* South Line/Sec 28/T7N,R16W 1832 1976 Sk Cor 2046.00' (623.62 m) 2084.41' (635.33 m) + 38.41' (+ 11.71 m) +0.27' (+0.082 m) M22* South Line/Sec 17/T7N.R16W 1832 1977 SE Cor 429.00' (130.76 m) 283.30' ( 86.35 m) - 145.70 ( . 44.41 m ) -1 .0 0 ' (-0.305 m) M20 Table C2 ( c o n t ' d . ). S ite No. Section Line Location M239 South Line/Sec 32/T8N,R16W Year Resur­ vey: of This GLO Survey Study 1832 1977 Point of Survey O rigin GLO Distance To "Meander Line" S% Cor 462.00' (140. 82 m) B l u f f Crest 1976-77 Change Di stance GLO Date To B l u f f Crest To 1976-77 470.00* 410.20' + - 8.00* 51.80' Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 +0.06* -0.36* 143.26 m 125.03 m + 2.44 m - 15.79 m +0.018 m -0.110 m MUSKEGON COUNTY M24 South Line/Sec 8/T10N,R17W 1837 1977 S% Cor 2593.80' (790.59 m) 2289.57' (697.86 m) - 304.23' ( - 92.73 m) -2 .1 7 ' (-0.661 m) M25 South Line/Sec 6/T10N,R17W 1837 1977 SE Cor 2393.82' (729.64 m) 2289.60' (697.87 m) - 104.22' (- 31.77 m) -0 .7 4 ' (-0.226 m) M26h North Line/Sec 1/T10N,R18W 1836 1977 NE Cor 943.80' (287.67 m) 794.00' (242.01 m) - 149.80' ( - 45.66 m) -1 .0 6 ' (-0.323 m) South Line/Sec 30/TllN,R17VJ 1837 1977 S% Cor 1848.00' (563.27 m) 1653.59' (504.01 m) - 194.41' (- 59.26 m) -1 .3 9 ' (-0.424 m) M28s South Line/Sec 35/T12N,R18Vv 1837 1977 S% Cor 1089.00' (331.93 m) 865.75' (263.88 m) - 223.25' (- 68.05 m) -1 .5 9 ' (-0.485 m) M27 Table C2 ( c o n t ' d . ). Site No. Section Line Location M29 South Line/Sec 27/T12N.R18W M30 South Line/Sec 15/T12N,R18W Year Resur­ vey: of This GLO Survey Study 1837 1977 Point of Survey O rigin SE Cor GLO Distance To "Meander Line" B l u f f Crest 1976-77 Change Distance G LO Date To B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 224.40' ( 68.40 m) ( 21.50' 6.55 m) - 202.90' ( - 61.84 in) -1 45' (-0.442 m) 1837 1977 S% Cor 458.70' (139.81 m) 269.50' ( 82.14 m) - 189.20' (- 57.67 m) -1 .3 5 ' (-0.411 m) 1837 1977 SE Cor 1155.00' (“352.04 m) 1155.00' 1089.00* 0.00' - 66.00* 0 .00' -0.47* 352.04 m 331.93 m 0.00 m - 20.17 m 0.000 m -0.143 m OCEANA COUNTY M319 South Line/Sec 33/T13N,R18W M32 South Line/Sec 24/T14N,R18W 1837 1977 SE Cor 2057.88' (627.24 m) 2100.76' (640.31 m) + 42.88' (+ 13.07 m) +0.31' (+0.094 m) M33 South Line/Sec 13/T14N.R19W 1837 1977 SE Cor 4125.00' (1257.30 m) 3810.80' (1161.53 m) - 314.20' (- 95.77 m) -2 .2 4 ' (-0.683 m) M34 South Line/Sec 2/T14N.R19W 1837 1977 SE Cor 627.00' (191.11 m) 612.25' (186.61 m) (- 14.75' 4.50 m) -0 .1 1 ' (-0.034 m) M35 South Line/Sec 35/T15N.R19W 1838 1977 SE Cor 726.00' (221.28 m) 448.80' (136.79 m) - 277.20' (- 84.49 m) -1 .9 9 ' (-0.607 m) Table C2 ( c o n t ' d . ). S ite No. Section Line Location M36® South Line/Sec 2/T16N,R18W Year Resur­ of vey: This GLO Survey Study Point of Survey O rigin GLO Distance To "Meander Line" 1977 S% Cor 810.00' (247.03 m) 1838 1976-77 B l u f f Crest Distance Change GLO Date To B l u f f Crest To 1976-77 916.90' 762.63* + 106.42' - 47.85' Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 +0.77' -0.34* 279.47 m 232.45 m + 32.44 m - 14.58 m +0.235 m -0.104 m MASON COUNTY M37 South Line/Sec 10/T17N,R18W 1838 1977 SE Cor 541.20' (164.96 m) 429.80' (131.00 m) - 111.40' (- 33.95 m) -0 .8 0 ' (-0.244 m) M38 South Line/Sec 34:/T18N,R18W 1838 1977 SE Cor 1801.80' (549.19 m) 1715.10' (522.76 m) - 86.70' ( - 26.43 m) -0 .6 2 ' (-0.189 m) M39 South Line/Sec 19/T19NSR18W 1838 1977 SE Cor 350.46' (106.82 m) 448.10' (136.58 m) + 97.64' (+ 29.76 m) +0.70' (+0.213 m) M40 South Line/Sec 14/T20N,R18W 1839 1977 SE Cor 1108.80' (337.96 m) 1213.05' (369.74 m) + 104.25' (+ 31.78 m) +0.76' (+0.232 m) South Line/Sec 28/T21NsR17W 1839 1977 S% Cor 245.52' ( 74.83 m) 111.00' ( 33.83 m) - 134.52' ( - 41.00 m) -0 .9 7 ' (-0.296 m) MANISTEE COUNTY M41 Table C2 ( c o n t ' d . ). 1976-77 B l u f f Crest Change Distance To GLO Date B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 2657.52' (810.01 m) - 72.24' ( - 22.02 m) -0 .5 2 ' (-0.158 m) 1923.24' (586.20 m) 1674.33' (510.34 m) - 248.91' ( - 75.87 m) -1 .9 1 ' (-0.582 m) SE Cor 1345.08' (409.98 m) 1000.50' (304.95 m) - 344.58' (-105.03 m) -2 .6 5 ' (-0.808 m ) 1977 Sk Cor 1650.00' (502.92 m) 1521.00' (463.60 m) - 129.00' (- 39.32 m) -0 .9 9 ' (-0.302 m) 1847 1977 SE Cor 2215.62' (675.32 m) 2151.21' (655.69 m) - 64.41' ( - 19.63 m) -0 .5 0 ' (-0.152 m) Centerline/Sec 24/T22N.R17W (N. Indian Reserve Line) 1847 1977 Ek Cor 1048.08' (319.45 m) 905.10' (275.87 m) - 142.98' ( - 43.58 m) - 1 .1 0 ’ (-0.335 m) M48 South Line/Sec 5/T22N,R16W 1839 1977 Sk Cor 1658.58' (505.54 m) 1418.90' (432.48 m) - 239.68' (- 73.05 m) -1 .7 4 ' (-0.530 m) M49 South Line/Sec 16/T23N,R16W 1839 1977 S% Cor 986.70' (300.75 m) 869.67' (265.08 m) - 117.03' (- 35.67 m) -0 .8 5 ' (-0.259 m) Point of Survey O rigin GLO Distance To "Meander Line" 1977 SE Cor 2729.76' (832.03 m) 1847 1977 E% Cor South Line/Sec !0/T21N,R17W 1847 1977 M45 South Line/Sec 25/T22N,R17W 1847 M46 South Line/Sec 24/T22N.R17W M47 Year Resur­ vey: of This GLO Survey Study S ite No. Section Line Location M42 South Line/Sec 15/T21N,R17W 1839 M43 Centerline/Sec 15/T21N,R17W (S. Indian Reserve Line) M44 Table C2 ( c o n t ' d . ) . S ite No. Section Line Location Year Resur­ of vey: This GLO Survey Study Poi nt of Survey O rigin GLO Distance To "Meander Line" B l u f f Crest 1976-77 Change Distance GLO Date To B l u f f Crest To 1976-77 Aver. Ann. B l u f f Crest Change GLO Date To 1976-77 BENZIE COUNTY M50 South Line/Sec 3/T25N,R16W 1838 1977 SE Cor 924.00' (281.64 m) 560.32' (170.79 m) - 363.68' (-110.85 m) -2 .6 2 ' (-0.799 m) LEELANAU COUNTY M51 South Line/Sec 13/T28N.R15W 1850 1977 SE Cor 1865.16' (568.50 m) 1857.82' (566.26 m) (- 7.34' 2.24 m) -0 .0 6 ' (-0.018 m) M52 South Line/Sec 12/T28N,R15W 1850 1977 SE Cor 1955.58' (596.06 m) 1911.83' (582.73 m) - 43.75' (- 13.34 m) -0 .3 4 ' (-0.104 m) M538 South Line/Sec 11/T29N,R14W 1850 1977 S% Cor 313.50' ( 95.55 m) 349.89' 278.89' + - 36.39' 34.611 +0.29' -0 .2 7 ' 106.65 m 85.01 m + 11.09 m - 10.55 m +0.088 m -0.082 m M54 South Line/Sec 36/T30N.R14W 1850 1977 SE Cor 1353.00' (412.39 m) 1302.90' (397.12 m) - 50.10' ( - 15.27 m) -0 .3 9 ' (-0.119 m) M55 South Line/Sec 17/T30N.R12W 1851 1977 SE Cor 258.06 ( 78.66 m) 66.00' ( 20.17 m) - 192.06' (- 58.54 m) -1 .5 2 ' (-0.463 m) M56 East Line/Sec 15/T32N,R11W 1855 1977 SE Cor 1452.00' (442.57 m) 1448.36' (441.46 m) (- -0.03* (-0.009 m) 3.64' 1.11 m) Table C2 ( c o n t ' d . ) . Footnotes °The b l u f f was receding r a p id ly u n t il 1971 at which time a m u lt i- m illio n d o lla r steel p ile and limestone block revetment and groin system was constructed northward from a p o in t j u s t south o f th is section lin e in order to p ro te ct highway and r a ilro a d rig h t-o f-w a y s . B l u f f recession has been minimal since 1971. The section lin e in te rs e c ts the b l u f f crest at an acute angle and at a po in t where a very large slump and some g u lly in g have occurred. Although b l u f f erosion and recession have been s ig n if ic a n t along t h is reach o f the shorezone the long-term recession rate f o r t h is s it e is probably somewhat higher than is representative o f the reach as a whole. *The section lin e coincides w ith the northern slope o f a ravine through which in te r m itta n t drainage flows. Except f o r a small cut the ravine mouth is blocked by low dunes; the resurvey measurement terminated a t the lakeward cre st o f these dunes. To the north and south b lu ff s ris e 43 to 50 fe e t and are composed o f sand o v e rlyin g t i l l . dBecause o f the rounded nature o f the crest and pedestrian t r a f f i c the p o s itio n o f the b l u f f lin e is somewhat ambiguous. 'Although re s u lts o f t h is property survey in d ica te d a b l u f f survey in d ica te d long-term net accretion comparison w ith a R.L.S. crest loss o f 8.8 fe e t between 1974 and 1976. f The resurvey measurement was c a rrie d to a lin e connecting the b l u f f cre st on e ith e r side o f the section li n e easement. The b l u f f at the easement was notched in 1973 when a drainage pipe was in s t a lle d . sAt four dune s ite s (M23, M31, M36, and M53) two d i s t i n c t b l u f f crests are recognized. The lakeward cre st is a b l u f f lin e o f a lo w e r - r e lie f dune terrace which fro n ts the more landward cre s t o f a somewhat h i g h e r - r e l ie f dune fe a tu re . Because o f the s itu a tio n and the lack o f c l a r i t y in the GLO notes i t is not possible to p o s it iv e ly ascertain to which p o in t the GLO measurement term inated; consequently, t h is stu d y's measurements were c a rrie d to each o f the two possible cre st lin e s and corresponding recession rates then determined. In the ta b le the upper fig u re pertains to measurements to the crest lin e o f the somewhat h ig h e r - r e l ie f landward dune form and the lower fig u re to measurements to the b l u f f Table C2 ( c o n t1d . ). lin e o f the lo w e r - r e lie f lakeward dune fe a tu re . In three o f the fo u r cases measurements to e it h e r crest in d ic a te d r e l a t i v e l y small change in b l u f f l in e p o s itio n r e la ti v e to the GLO surveys. The recession or accretion rates determined f o r the fo u r s ite s are not included in any o f the q u a n tita tiv e analysis performed in t h is study. In no way does t h is exclusion a f f e c t any o f the conclusions reached and, in f a c t , t h e i r in c lu s io n would only increase support f o r the fin d in g s reported. hDuring the high lake period o f the e a rly 1950's the water le ve l was up against the base o f the present b l u f f . However, during the low lake stage in the la te 1950's and e a rly 1960's a foredune terrace three to nine fe e t in height and at le a s t 65 to 75 fe e t in width had formed in fr o n t o f the present b l u f f ; t h is foredune has la r g e ly been removed by wave erosion during the present high water period. ‘Although there has been only minor "recent" erosion at the b l u f f cre st a t the section lin e lo c a tio n , erosion has reached the cre st several hundred fe e t to the north and south. LIST OF REFERENCES LIST OF REFERENCES Acres Consulting Services. 1976. The vegetation cover o f the Great Lakes Canadian s h o re lin e : i t s ro le in c o n t r o llin g rates o f erosion. Technical re p o rt to the Canadian Centre fo r Inland Waters, B u rlin g to n , O n ta rio , 78 pp. Alden, W.C. 1918. The Quaternary geology o f southeastern Wisconsin. U.S. Geological Survey Professional Paper No. 106, U.S. Government P r in tin g O ffic e , Washington, D.C., 356 pp. American Geological I n s t i t u t e . 1974. D ic tio n a ry o f geological terms. Anchor Books, Anchor/Doubleday, Garden C it y , N .Y., 545 pp. Andrews, E. 1870. The North American lakes considered as chronmeters o f p o s t-g la c ia l tim e. Chicago Academy o f Science Transactions, 2:1-23. B a ll , J.R. 1920. The in t e r c is io n o f Pike R ive r, near Kenosha, Wisconsin. I l l i n o i s Academy o f Science Transactions, 13:323-326. 1938. Wave erosion along the west shore o f Lake Michigan. The Chicago N a t u r a li s t , l ( l ) : l l - 2 0 . ________ and Powers, W.E. 1930. Shore recession in southeastern Wisconsin. I l l i n o i s Academy o f Science Transactions, 22:435-441. Berg, R.C. and C o llin is o n , C. 1976. B l u f f e rosion , recession rates and volum etric losses on the Lake Michigan shore in I l l i n o i s . I l l i n o i s State Geological Survey Environmental Note No. 76, Urbana, I l l i n o i s , 33 pp. B la lo c k , H.M., J r . 1972. Social S t a t i s t i c s . New York, N .Y ., 583 pp. McGraw-Hill Book Company, Bloom, A.L. 1978. Geomorphology: a systematic analysis o f la t e Cenozoic landforms. Prentice H a ll, I n c . , Englewood C l i f f s , N . J . , 510 pp. B ra te r, E.F. 1950a. Beach erosion in Michigan. Lake Hydraulics Laboratory Research P u b lica tio n No. 2, U n iv e rs ity o f Michigan, Ann A rb o r, Michigan, 39 pp. ________ 1950b. B ib lio g ra p h y o f beach erosion and re la te d su b je cts. Lake Hydraulics Laboratory Research P u b lica tio n No. 1, U n iv e r s ity o f Michigan, Ann A rb o r, Michigan, 86 pp. 189 190 ________ 1954. Low cost shore p ro te c tio n used on the Great Lakes. Proceedings o f the Fourth Conference on Coastal Engineering, pp. 214-226. ________ 1975. Beach erosion in Michigan: an h i s t o r i c a l review. Water Development Services D iv is io n , Bureau o f Water Manage­ ment, Michigan Department o f Natural Resources, Lansing, Michigan, 22 pp. ________ , Armstrong, J.M ., and M c G ill, M.R. 1974. M ichigan's demonstration erosion con tro l program: evaluation re p o rt. Michigan Department o f Natural Resources, Lansing, Michigan, 97 pp. ________ 1975. Michigan's demonstration erosion co n tro l program: update evaluation re p o rt. Michigan Department o f Natural Resources, Lansing, Michigan, 53 pp. ________ and Hyma, N.D. 1977. The Michigan demonstration erosion co n tro l program in 1976. Michigan Sea Grant Program Technical Report No. 55, prepared by the Coastal Zone Laboratory, U n iv e rs ity o f Michigan, Ann A rbor, Michigan, 71 pp. B ra te r, E .F ., B i l l i n g s , N. and Granger, D.W. 1952. Low-cost shore p ro te c tio n f o r the Great Lakes. Lake Hydraulics Laboratory P u b lic a tio n No. 3, U n iv e rs ity o f Michigan, Ann A rb o r, Michigan, 22 pp. B ra te r, E.F. and S e ib e l, E. 1973. An engineering study o f Great Lakes shore erosion in the lower peninsula o f Michigan. Water Resources Commission, Michigan Department o f Natural Resources, Lansing, Michigan, 47 pp. Breed, C .B., Hosmer, C.L. and Bone, A.J. 1970. The p r in c ip le s and p ra c tice s o f surveying: volume 1. elementary surveying. John Wiley and Sons, I n c . , New York, N .Y., 717 pp. B rin k e r, R.C. 1969. Elementary surveying. In te rn a tio n a l Textbook Company, Scranton, Pennsylvania, 620 pp. Brunk, I.W. 1960. P r e c ip ita tio n and the le v e ls o f Lakes Michigan and Huron. Proceedings o f the Third Conference on Great Lakes Research, Great Lakes Research D iv is io n , U n iv e r s ity o f Michigan, Ann Arbor, Michigan, pp. 145-150. Brunn, P. 1962. Sea-level r is e as a cause o f shore e ro s io n . Journal o f the Waterways and Harbors D iv is io n , Proceedings o f the American Society o f C iv il Engineers, 88(WW1):117-130. B u ckle r, W.R. 1973a. B l u f f erosion a t selected s ite s along the southeastern shore o f Lake Michigan. Unpublished M.A. research paper, Michigan State U n iv e r s ity , East Lansing, Michigan, 68 pp. 191 ________ 1973b. V a ria tio n s in water le v e l and p r e c ip it a t io n in the Lake Michigan basin. Unpublished M.A. research paper, Michigan State U n iv e r s it y , East Lansing, Michigan, 53 pp. ________and W inters, H.A. 1975. Rates o f b l u f f recession a t selected s ite s along the southeastern shore o f Lake Michigan. Michigan Academician, 8 (2 ):1 7 9 -18G. Buddecke, R. 1973. Help y o u r s e lf - a discussion o f the c r i t i c a l erosion problem on the Great Lakes. Shore and Beach, 41(2):15-17. ________ 1974. Erosion and recession ra te a n a ly s is . In Michigan L e g is la tu re , Proceedings o f the Great Lakes Shore!ands Conference, Lansing, Michigan, pp. 5-7. C a rte r, C.H. 1975. Recession ra te measurement techniques. In Great Lakes Basin Commission, Proceedings o f the Recession Rate Workshop, Ann A rb o r, Michigan, pp. 159-167. Chamberlin, T.C. 1877. Geology o f eastern Wisconsin. Geology o f Wisconsin: Survey o f 1873-1877. Wisconsin Geological and Natural H is to ry Survey, Madison, Wisconsin, pp. 93-405. C h ie ru z zi, R. and Baker, R.F. 1958. A study o f Lake Michigan b l u f f recession. Engineering S ta tio n B u lle t in No. 172, Ohio State U n iv e r s ity , Columbus, Ohio, 100 pp. ________ 1959. In v e s tig a tio n o f b l u f f recession along Lake E rie . Journal o f the Waterways and Harbors D iv is io n , Proceedings o f the American Society o f C iv i l Engineers, 85(WW4):109-132. Coastal Measurement Workshop. Coastal 1976. Coastal Research, 4 ( 9 ) :1 -4 . Zone Laboratory, U n iv e rs ity o f Michigan. 1975. Great Lakes s h o re line damage survey: Muskegon County, Manistee County, Chippewa County and Alcona County, Michigan. Prepared f o r the U.S. Army Corps o f Engineers, North Central D iv is io n , Chicago, Illin o is . C o llin s o n , C. and Berg, R.C. 1976. B l u f f erosion processes, recession rates and v o lu m e tric losses o f the Lake Michigan shore in I l l i n o i s ( a b s .) . N orth-Central Section, Geological Society o f America A b s tra c t With Program, 8(4):473. C o llin s o n , C ., Lineback, J . A . , DuMontelle, B. and Brown, D.C. 1974. Coastal geology, sedimentology, and management - Chicago and the Northshore. I l l i n o i s State Geological Survey Guidebook Series No. 12, Urbana, I l l i n o i s , 55 pp. Consoer, Townsend and Associates. 1973. V illa g e o f Fox P o in t, Wisconsin. Shoreline erosion study fo r Chicago, I l l i n o i s , 74 pp. 192 Cowles, H.C. 1899. Ecological r e la tio n s o f the vegetation o f the sand dunes o f Lake Michigan. Botanical Gazette, 27:95-117, 167-202, 281-308, 361-391. Dai, T .S ., H i l l , I. K . and Smith, D.W. 1977. The ro le o f vegetation in s t a b i l i z i n g the lower Great Lakes Canadian s h o re lin e . Journal o f Great Lakes Research, 3(1-2 ):4 6 -5 6 . Davis, R.A., J r. ( e d .) . 1970. Coastal sedimentation o f southeastern Lake Michigan. Studies in Geology No. 1, Department o f Geology, Western Michigan U n iv e r s ity , Kalamazoo, Michigan, 50 pp. ________ 1971. Systematic beach p r o f i l e study o f eastern Lake Michigan (1970-1971). Annual status re p o rt o f c o n tra c t DACW72-70-C-0037, Coastal Engineering Research Center, U.S. Army Corps o f Engineers; mimeographed r e p o r t , Department o f Geology, Western Michigan U n iv e r s ity , Kalamazoo, Michigan, 49 pp. ________ 1972. Systematic beach p r o f i l e study o f eastern Lake Michigan. Final re p o rt o f c o n tra c t DACW72-70-C-0037, Coastal Engineering Research Center, U.S. Army Corps o f Engineers; mimeographed r e p o r t, Department o f Geology, Western Michigan U n iv e rs ity , Kalamazoo, Michigan, 34 pp. ______ _ 1973a. Coastal ic e formation and i t s e f f e c t on beach sedimentation. Shore and Beach, 4 1 (1 ):3 -9 . ________ 1973b. Systematic beach p r o f i l e study: eastern Lake Michigan beaches. Unpublished re p o rt to Coastal Engineering Research Center, U.S. Army Corps o f Engineers, Fort Bel v o i r , V ir g in ia . ________ 1976. Coastal changes, eastern Lake Michigan, 1970-73. Coastal Engineering Research Center Technical Paper No. 76-16, U.S. Army Corps o f Engineers, Fort B e lv o ir , V i r g in ia , 64 pp. ________ and F in g le to n , W.G. 1972. Systematic beach p r o f i l e study o f eastern Lake Michigan (1971-1972). Annual status re p o rt o f c o n tra c t DACW72-70-C-0037, Coastal Engineering Research Center, U.S. Army Corps o f Engineers; mimeographed r e p o r t, Department o f Geology, Western Michigan U n iv e r s ity , Kalamazoo, Michigan, 40 pp. ________ 1973. Recent erosion rates along eastern Lake Michigan (a b s .). Proceedings o f the Sixteenth Conference on Great Lakes Research, In te rn a tio n a l A ssociation f o r Great Lakes Research, U n iv e rs ity o f Michigan, Ann A rb o r, Michigan, pp. 58-59. ________ and P r it c h e t t , P.C. 1975. Beach p r o f i l e changes: east coast o f Lake Michigan, 1970-72. Coastal Engineering Research Center Miscellaneous Paper No. 10-75, U.S. Army Corps o f Engineers, Fort B e lv o ir , V i r g in i a , 97 pp. 193 Davis, R .A., J r . and Fox, W.T. 1971. Beach and nearshore dynamics in eastern Lake Michigan. Technical Report No. 4, ONR c o n tra c t 388-092, O ffic e o f Naval Research, Washington, D.C., 145 pp. ________ 1972a. Coastal processes and nearshore sand bars. o f Sedimentary Petrology, 4 2 (2 ):401-412. Journal ________ 1972b. Four-dimensional model fo r beach and nearshore sedimentation. Journal o f Geology, 80:483-493. ________ 1974. Simulation process-response study on the east and west coasts o f Lake Michigan. Technical Report No. 13, ONR c o n tra c t 388-092, O ffic e o f Naval Research, Washington, D.C., 61 pp. Davis, R.A., J r . and McGeary, D.F.R. 1965. S t a b i l i t y in nearshore bottom topography and sediment d i s t r i b u t i o n , southeastern Lake Michigan. Proceedings o f the Eighth Conference on Great Lakes Research, Great Lakes Research D iv is io n , U n iv e rs ity o f Michigan, Ann Arbor, Michigan, pp. 222-231. Davis, R.A., J r . , S e ib e l, E. and Fox, W.T. 1973. Coastal erosion in eastern Lake Michigan - causes and e f f e c t s . Proceedings o f the Sixteenth Conference on Great Lakes Research, In te rn a tio n a l A ssociation f o r Great Lakes Research, U n iv e rs ity o f Michigan, Ann Arbor, Michigan, pp. 404-412. Davis, R.E., Foote, F.S. and K e lle y, J.W. 1966. Surveying: theory and p r a c tic e . McGraw-Hill Book Company, New York, N .Y ., 1096 pp. Day, P.C. 1926. P r e c ip ita tio n in the grainage area o f the Great Lakes, 1875-1924. Monthly Weather Review, 5 4 (3 ):85-106. DeGroot, R. 1977. B l u f f recession o f Racine County, Wisconsin: p re lim in a ry r e s u lts . Unpublished r e p o r t, Sea Grant Advisory Services, U n iv e rs ity o f Wisconsin-Extension, Madison, Wisconsin, 9 pp. Dolan, R. and Basserman, K. 1972. Shoreline erosion and the l o s t colony. A ssociation o f American Geographers Annals, 62(3): 424-426. Dooley, J .P ., C lin to n , F.A. and Jannereth, M.R. 1975. Shorelands management using remote sensing techniques. Proceedings o f the Tenth In te rn a tio n a l Symposium On Remote Sensing o f Environment, Volume 11, Center f o r Remote Sensing Inform ation and A n a ly sis , Environmental Research I n s t i t u t e o f Michigan, Ann A rb o r, Michigan, pp. 1447-1450. DuBois, R.N. 1976. Nearshore evidence in support o f the Brunn ru le on shore erosion. Journal o f Geology, 8 4 (4 ) :485-491. 194 E d il, T.B. and V a lle jo , L.E. 1977. Shoreline erosion and la n d slid e s in the Great Lakes. Sea Grant College Program Advisory Report No. 15, U n iv e r s ity o f Wisconsin, Madison, Wisconsin, 7 pp. E d il, T .B ., Mickelson, D.M. and Acomb, L .J . 1977. R e lationship o f geotechnical p ro p e rtie s to g la c ia l s t r a t ig r a p h ic u n its along Wisconsin's Lake Michigan s h o re lin e . Department o f C i v il and Environmental Engineering and Engineering Mechanics and Geology, U n iv e rs ity o f Wisconsin, Madison, Wisconsin, 30 pp. Evans, O.F. 1940. The low and b a ll o f the eastern shore o f Lake Michigan. Journal o f Geology, 48:476-511. Evenson, E.B. 1973. The ic e - f o o t complex: i t s morphology, c la s s i f i c a t i o n , mode o f fo rm a tio n , and importance as a sediment tra n s p o rtin g agent. The Michigan Academician, 5 1 (l):4 3 -5 8 . Farrand, W.R. 1969. Geological re p o rt on the Ludington pumped storage p r o je c t. Unpublished r e p o r t, purchased co n tra ct E-10052, EBASCO S ervices, I n c . , 23 pp. _________ 1970. Rate o f recession o f the Lake Michigan b l u f f along the Ludington pumped storage p r o je c t. Unpublished re p o r t, purchased c o n tra c t E-10052, EBASCO Services, I n c . , 21 pp. F in gleto n , W.G. 1973. A study o f shore erosion a t seventeen s ite s along eastern Lake Michigan. Unpublished M.A. th e s is , Western Michigan U n iv e r s ity , Kalamazoo, Michigan. F l i n t , F.F. 1971. G lacial and Quaternary geology. Sons, I n c . , New York, N.Y., 892 pp. John Wiley and Fox, W.T. and Davis, R.A., J r . 1970a. Fourier a n a lysis o f weather and wave data from Lake Michigan. Technical Report No. 1, ONR co n tra c t 388-092, O ffic e o f Naval Research, Washington, D.C., 47 pp. _________ 1970b. P r o f ile o f a storm - wind, waves and erosion on the southeastern shore o f Lake Michigan. Proceedings o f the Thirteen Conference f o r Great Lakes Research, In te rn a tio n a l A ssociation f o r Great Lakes Research, U n iv e rs ity o f Michigan, Ann Arbor, Michigan, pp. 233-241. _________ 1971a. Computer sim u la tio n model o f coastal processes in eastern Lake Michigan. Technical Report No. 5, ONR c o n tra c t 388-092, O ffic e o f Naval Research, Washington, D.C., 114 pp. _________ 1971b. F o u rie r a n a lys is o f weather and wave data from Holland, Michigan, Ju ly 1970. Technical Report No. 3, ONR c o n tra ct 388-092, O ffic e o f Naval Research, Washington, D.C., 79 pp. 1973a. Coastal processes and beach dynamics a t Sheboygan, Wisconsin, J u ly 1972. Technical Report No. 10, ONR c o n tra ct 388-092, O ffic e o f Naval Research, Washington, D.C., 94 pp. 195 1973b. Sim ulation model f o r storm cycles and beach erosion on Lake Michigan. Geological Society o f America B u ll e t in , 84: 1769-1790. Frankovic, E.A. 1975. An a e ria l photographic in t e r p r e t a t io n and physical model study o f Lake Michigan s h o re lin e erosion in the v illa g e s o f W hitefish Bay, Fox P o in t, and Shorewood, Wisconsin. Unpublished M.S. th e s is , U n iv e rs ity o f Wisconsin, Milwaukee, Wisconsin, 55 pp. Gary, M., McAfee, R., J r . , and Wolf, C.L. ( e d it o r s ) . 1972. Glossary o f geology. American Geological I n s t i t u t e , Washington, D.C., 805 pp. Gelinas, P.J. and Quigley, R.M. 1973. The in flu e n ce o f geology rates along the north shore o f Lake E rie . Proceedings o f the Sixteenth Conference on Great Lakes Research, In te rn a tio n a l Association f o r Great Lakes Research, U n iv e rs ity o f Michigan, Ann Arbor, Michigan, pp. 421-430. G iffo r d , A.R. and Humphrys, C.R. 1966. Lake shore c l a s s i f ic a t i o n : southern peninsula o f Michigan. Department o f Resource Development and A g r ic u ltu r a l Experiment S ta tio n , Michigan State U n iv e r s ity , East Lansing, Michigan, 2 sheets. G oldthw ait, J.W. 1907. The abandoned shorelines o f eastern Wisconsin. Wisconsin Geological and Natural H is to ry Survey B u lle t in No. 17, Madison, Wisconsin, 134 pp. ________ 1908. I n t e r c is io n , a p e c u lia r m o d ific a tio n o f drainage. Science and Mathematics, 8(2):129-139. School Gorder, L. 1975. The coastal zone in northeastern Wisconsin. In Zakrzewska-Borowiecki, B. ( e d .) , Landscapes o f Wisconsin: A F ie ld Guide, prepared f o r the annual meeting o f the Association o f American Geographers, Milwaukee, Wisconsin, pp. 52-68. Gove Engineers, Inc. 1970. Beach and b l u f f erosion on Lake Michigan between the c i t y o f S t. Joseph and Grand Mere Lakes, Berrien County, Michigan. Report prepared f o r the Lakeshore Chamber o f Commerce. Granger, D.W. 1957. Beach erosion in Michigan. 2 5 (1 ):20-23. Shore and Beach, Gray, D.H. 1975. The r o le and use o f vegetation f o r the p ro te c tio n o f backshore slopes in the coastal zone. Mimeographed re p o rt, Department o f C iv il Engineering, U n iv e rs ity o f Michigan, Ann Arbor, Michigan, 30 pp. ________ 1977. The in flu e n c e o f vegetation on slope processes in the Great Lakes re gion . In Great Lakes Basin Commission, Proceedings o f the Workshop on the Role o f Vegetation in S t a b iliz in g o f the Great Lakes S h o re lin e , Ann Arbor, Michigan, pp. 5-29. 196 Great Lakes Basin Commission. 1974, Proceedings o f the recession ra te workshop. Ann Arbor, Michigan, 234 pp. ________ 1975. Shore use and erosion. Great Lakes Basin Framework Study, Appendix No. 12, Ann Arbor, Michigan, 111 pp. ________ 1977. The ro le o f vegetation in s h o re lin e management: a guide fo r Great Lakes sho re line property owners. Ann A rbor, Michigan, 32 pp. ________ and U.S.D.A. Soil Conservation Service. 1977. Great Lakes vegetation workshop proceedings. Great Lakes Basin Commission, Ann Arbor, Michigan, 113 pp. Hadley, D.W. 1974. A geological reconnaissance o f Bender County Park, Milwaukee County, Wisconsin. U n iv e rs ity o f Wisconsin-Extension Open F ile Report, Wisconsin Geological and Natural H is to ry Survey, Madison, Wisconsin, 7 pp. ________ 1975. Proposal f o r a geological and geotechnical in v e s tig a tio n f o r erosion problem areas along Wisconsin's Great Lakes sh o re line ( d r a f t ) . Wisconsin Geological and Natural H isto ry Survey, Madison, Wisconsin, 9 pp. ________ 1976. Shoreline erosion in southeastern Wisconsin. Wisconsin Geological and Natural H isto ry Survey Special Report No. 5, Madison, Wisconsin, 33 pp. H a ll, V.L. and Ludwig, J.D. 1975. Evaluation o f p o te n tia l use o f vegetation f o r erosion abatement along the Great Lakes s h o re lin e . Coastal Engineering Research Center Miscellaneous Paper No. 7-75, U.S. Army Corps o f Engineers, Fort B e lv o ir , V i r g in ia . Hands, E.B. 1970. A geomorphic map o f Lake Michigan s h o re lin e . Proceedings o f the T h irte e n th Conference on Great Lakes Research, In te rn a tio n a l Association f o r Great Lakes Research, U n iv e rs ity o f Michigan, Ann A rbor, Michigan, pp. 250-265. ________ 1976. Observations o f barred coastal p r o f il e s under the in flu e n c e o f r i s i n g water le v e ls , eastern Lake Michigan, 1967-71. Coastal Engineering Research Center Technical Report No. 76-1, U.S. Army Corps o f Engineers, Fort B e lv o ir , V i r g in ia , 113 pp. Hanson, S.N., Perry, J.S. and Wallace, W. 1977. Great Lakes shore erosion p ro te c tio n : a general review w ith case s tu d ie s . Wisconsin Coastal Management Program, Madison, Wisconsin, 106 pp. Haras, W.S. 1975. Recession ra te measurement techniques: a c r i t i q u e . In Great Lakes Basin Commission, Proceedings o f the Recession Rate Workshop, Ann Arbor, Michigan, pp. 169-179. 197 ________ 1977. The r o le o f vegetation in re ta rd in g shore erosion on the Canadian Great Lakes s h o re lin e . In Great Lakes Basin Commission and U.S.D.A. S o il Conservation Service, Proceedings o f the Workshop on the Role o f Vegetation in S t a b iliz in g o f the Great Lakes S h o re lin e , Great Lakes Basin Commission, Ann Arbor, Michigan, pp. 69-75. Harman, J .R ., Rosen, R. and Corcoran, W. 1980. Winter cyclones and c ir c u la t io n p atterns on the western Great Lakes. Physical Geography, 1 (1):2 8 -4 1 . H a rtfo rd , F. and Tanner, W.F. 1976. Current Great Lakes shore damage. Shore and Beach, 44(1):16-19. Hawley, E.F. and Judge, C.W. 1969. C h a ra c te ris tic s o f Lake Michigan bottom p r o f il e s and sediments from Lakeside, Michigan to Gary, Indiana. Proceedings o f the Tw elfth Conference on Great Lakes Research, In te rn a tio n a l A ssociation f o r Great Lakes Research, U n iv e rs ity o f Michigan, Ann Arbor, Michigan, pp. 198-209. Herbert, T.A. 1974. An a n a lysis o f the physical and legal aspects o f erosion on Lake Michigan, a case study a t St. Joseph, Michigan. Unpublished Ph.D. d is s e r t a t io n , Michigan State U n iv e r s ity , East Lansing, Michigan, 244 pp. Hulsey, J.D. 1963. Beach sediments o f eastern Lake Michigan. Unpublished Ph.d. d is s e r t a t io n , U n iv e rs ity o f I l l i n o i s , Champaign-Urbana, I l l i n o i s , 155 pp. Humphrys, C.R., Horner, R.N. and Rogers, J.H. 1958. Shoreline c l a s s i f i c a t i o n o f . . . County, Michigan. Shoretype B u lle tin s Nos. 1-29, Department o f Resource Development and A g r ic u ltu r a l Experiment S ta tio n , Michigan State U n iv e r s ity , East Lansing, M ichigan. I l l i n o i s Coastal Zone Management Program. 1978. Harmony w ith the la ke : guide to b l u f f s t a b i l i z a t i o n . D iv is io n o f Water Resources, I l l i n o i s Department o f T ra n s p o rta tio n , Chicago, I l l i n o i s . I l l i n o i s Department o f Public Works and B u ild in g s . 1958. In te rim re p o rt f o r erosion c o n tr o l: I l l i n o i s shore o f Lake Michigan. D iv is io n o f Waterways, S p r in g fie ld , I l l i n o i s , 108 pp. In te rn a tio n a l Great Lakes Levels Board. 1973. Regulation o f Great Lakes water le v e ls . Report to the In te rn a tio n a l J o in t Commission, Ottawa, O ntario and Chicago, I l l i n o i s , 294 pp. Jannereth, M.R. 1975. State recession ra te program: Michigan. In Great Lakes Basin Commission, Proceedings o f the Recession Rate Workshop, Ann A rb o r, Michigan, pp. 13-29. 198 K e i l l o r , J.P. and DeGroot, R. 1978. Recent recession o f Lake Michigan shorelines in Racine County, Wisconsin. U n iv e rs ity o f Wisconsin Sea Grant College Program Special Report No. 507, Madison, Wisconsin, 42 pp. + appendix. King, C.A.M. 1972. Beaches and coasts. N.Y., 570 pp. Kingery, R. 1944. 1 2 (1 ):7. S t. M a rtin 's Press, New York, Recent Great Lakes s h o re lin e damage. Shore and Beach, K le in , W.H. 1957. P rin c ip a l tra cks and mean frequencies o f cyclones and anticyclones in the northern hemisphere. U.S. Weather Bureau Research Paper No. 40, U.S. Government P r in tin g O f f ic e , Washington, D.C., 60 pp. Knutson, P.L. 1977. Federal la b o ra to ry begins d une-building experiment. Communicator, 7 (1 4 ):5 -6 , Great Lakes Basin Commission, Ann Arbor, Michi gan. Krumbein, W.C. 1950. L i t t o r a l processes in lakes. Proceedings o f the F i r s t Conference on Coastal Engineering, pp. 155-160. Lake Michigan Federation. 1973. Papers from Lake Michigan sho re line planning conference, May 24 & 25, 1973. Chicago, I l l i n o i s , 198 pp. ________ 1978. Waves a gainst the shore: an erosion manual f o r the Great Lakes re g io n , Chicago, I l l i n o i s , 31 pp. Lapham, I.A . 1847. On the existence o f c e r ta in la c u s trin e deposits in the v i c i n i t y o f the Great Lakes u s u a lly confounded w ith the " d r i f t . " American Journal o f Science (2nd S e rie s ), 3-,90-94. Larsen, C.E. 1972. The c u lt u r a l v a ria b le in shore erosion along the I l l i n o i s shore o f Lake Michigan. The Lake Michigan Federation, Chicago, I l l i n o i s , 20 pp. ________ 1973. V a ria tio n in b l u f f recession in r e la t io n to lake le ve l f lu c tu a t io n along the high b l u f f I l l i n o i s shore. I l l i n o i s I n s t i t u t e o f Environmental Q u a lity Document No. 73-14, Chicago, I l l i n o i s , 73 pp. Lasca, N.P. n .d . Annotated b ib lio g ra p h y o f Lake Michigan shore erosion and nearshore process s tu d ie s . Mimeographed r e p o r t, Department o f Geological Sciences, U n iv e r s ity o f Wisconsin, Milwaukee, Wisconsin. League o f Women Voters. 1974. Shoreline e rosion . Lake Michigan Inter-League Group, Glenview, I l l i n o i s , 12 pp. 199 Lee, K.K. 1975. B l u f f recession in Lake Michigan sh o re line erosion . Journal o f S oil and Water Conservation, 30(3):138-139. L e v e re tt, F. 1899. The I l l i n o i s g la c ia l lobe. U.S. Geological Survey Monograph No. 38, U.S. Government P rin tin g O f fic e , Washington, D .C ., 817 pp. Maresca, J.W., J r . 1975. B l u f f l i n e recession, beach change, and nearshore change re la te d to storm passages along southeastern Lake Michigan. Unpublished Ph.D. d is s e r ta t io n , U n iv e rs ity o f Michigan, Ann Arbor, Michigan, 481 pp. Marks, W.D. 1977. A fiv e - y e a r review o f the Michigan demonstration erosion con tro l program. Shore and Beach, 45(4):13-17. ________ and C lin to n , F.A. 1974. Michigan demonstration erosion co n tro l program. Shore and Beach, 4 2 (2 ) :11-17. Marsh, W. 1977. Hard water coast guard. Magazine, 46(2):12-16. The Michigan Natural Resources M a rtin , H.M. 1955. Map o f the surface formations o f the southern peninsula o f Michigan. Michigan Geological Survey D iv is io n P u b lica tio n No. 49, Department o f Conservation, Lansing, Michigan. M a rtin , L. 1965. The physical geography o f Wisconsin. The U n iv e rs ity o f Wisconsin Press, Madison, Wisconsin, 608 pp. (Reproduction o f the 1932 e d i t i o n . ) Maxwell, H. 1919. Lake Michigan's encroachment on i t s coasts. S c i e n t i f i c American, 120:699-700. Michigan Department o f Natural Resources. 1973. shoreland. Lansing, Michigan, 135 pp. A plan fo r M ichigan's Michigan D iv is io n o f Land Resource Programs. 1979a. Great Lakes shoreland e rosion. Department o f Natural Resources, Lansing, Michigan, 10 pp. ________ 1979b. Local zoning f o r high r i s k erosion areas. o f Natural Resources, Lansing, Michigan, 63 pp. Department Michigan L e g is la tu re . 1974. Proceedings o f the Great Lakes shorelands conference, September 4 -6 , 1974. Lansing, Michigan, 91 pp. Michigan Water Resources Commission. 1970. Great Lakes s h o re lin e management and erosion control f o r Michigan. Department o f Natural Resources, Lansing, Michigan. ________ 1972a. Erosion o f the Michigan Great Lakes coastal lands. Department o f Natural Resources, Lansing, Michigan, 18 pp. 200 ________ 1972b. A special re p o rt on Great Lakes shore erosion. prepared a t the request o f the members o f the Michigan le g is l a t u r e , Department o f Natural Resources, Lansing, Michigan, 43 pp. Report ________ 1972c. Summary: a plan f o r Michigan's shorelines ( d r a f t ) . Department o f Natural Resources, Lansing, Michigan, 12 pp. Mickelson, D.M., Acomb, L . , Brouwer, N., E d il , T ., F rick e , C., Haas, B., Hadley, D., Hess, C., Klauk, R., Lasca, N. and Schneider, A. 1977. Shoreline erosion and b l u f f s t a b i l i t y along Lake Michigan and Lake Superior shorelines o f Wisconsin. Shore Erosion Study Technical Report, Wisconsin Coastal Management Program, O ffic e o f State Planning and Energy, Madison, Wisconsin, 199 pp. + 8 county appendices. M it c h e ll, J.K. 1974. Community response to coastal erosion: in d iv id u a l and c o lle c t iv e adjustments to hazards on the A t la n t ic shore. Department o f Geography Research Paper No. 156, U n iv e rs ity o f Chicago, Chicago, I l l i n o i s , 209 pp. M onteith, T .J . 1977. Shoreline erosion: the la rg e s t source o f sediment to the Great Lakes. Communicator, 8 ( 1 ) :5 - 6 , Great Lakes Basin Commission, Ann Arbor, Michigan. ________ and Sonzogni, W.C. 1976. U.S. Great Lakes sho re line erosion lo a d in g . In te rn a tio n a l Reference Group on Great Lakes P o llu tio n From Land Use A c t i v i t i e s , In te rn a tio n a l J o in t Commission, Windsor, O n ta rio , 211 pp. M u lle r, F .B ., Gervais, J.C. and Shaw, R.W. 1965. The e ffe c ts o f p r e c i p it a t io n on the le v e ls o f Lake Michigan-Huron. CIR-4264, TEC-576, Meteorological Branch, Canada Department o f Transport. Murphy, W.G. and Heim, G.E., J r . 1968. Slope s t a b i l i t y problems, Lake Michigan b l u f f , Milwaukee, Wisconsin (abs. ) . Geological Society o f America Special Paper No. 101, p. 148. N a p o li, J. 1975. The coasts o f Wisconsin. Wisconsin Sea Grant College Program, U n iv e rs ity o f Wisconsin, Madison, Wisconsin, 33 pp. N iendorf, D.W., O'Connell, W.S., e t a l . ( e d it o r s ) . 1967. Manitowoc County outdoors. Conservation Education, Inc. o f Manitowoc County and Manitowoc County Soil and Water Conservation D i s t i c t , Manitoowoc, Wisconsin, 129 pp. O'Hara, N.W. and Ayers, J.C. 1972. Stages o f shore ice development. Proceedings o f the F ifte e n th Conference on Great Lakes Research, In te rn a tio n a l A sso cia tio n f o r Great Lakes Research, U n iv e rs ity o f Michigan, Ann A rbor, Michigan, pp. 521-535. 201 Olson, C.E. 1974. Determining s h o re lin e recession rates from e x is tin g a e ria l photography. In Michigan L e g is la tu re , Proceedings o f the Great Lakes Shoreland Conference, Setember 4-6, 1974, Lansing, Michigan, pp. 8-11. Olson, J.S. 1958a. Lake Michigan dune development: 1. w in d -v e lo c ity p r o f il e s . Journal o f Geology, 6 6 (3 ) :254-263. ________ 1958b. Lake Michigan dune development: 2. plants as agents and to o ls in geomorphology. Journal o f Geology, 66(4):245-351. ________ 1958c. Lake Michigan dune development: 3. la k e - le v e l, beach, and dune o s c i l l a t i o n s . Journal o f Geology, 6 6 (5 ) :473-483. Omohundro, W. 1973. High water and s h o re lin e erosion on the Great Lakes. Shore and Beach, 41(1):14-18. Parker, R.W. 1971 Non l i n e a r i t y in coastal geomorphic processes. In Yatsu, E . , Dahms, F .A ., Falconer, A ., Ward, A .J . and Wolfe, J.S. ( e d i t o r s ) , Research Methods In Geomorphology, Proceedings, F i r s t Symposium on Geomorphology, 1969, Geographical P u b lic a tio n No. 1, Department o f Geography, U n iv e rs ity o f Guelph, Science Research Associates L t d . , Don M i l l s , O n ta rio , pp. 117-126. P a u li, R.K. and P a u li, R.A. 1977. Geology o f Wisconsin and upper Michigan in c lu d in g parts o f adjacent s ta te s . Kendall/Hunt P ublishing Company, Dubuque, Iowa, 232 pp. Pincus, H.J. 1962. Recession o f Great Lakes s h o re lin e s . In Pincus, H . J . ( e d . ) , Great Lakes Basin, American A ssociation f o r the Advancement o f Science P u b lic a tio n No. 71, Washington, D.C., pp. 123-137. 1964. Retreat o f lakeshore b l u f f s . Journal o f Waterways and Harbor D iv is io n , Proceedings o f the American Society o f C iv il Engineers, 90(WW1):115-134. P l a t t , R.H. 1978. Coastal hazards and n a tio n a l p o lic y : a j u r y - r i g approach. Journal o f the American I n s t i t u t e o f Planners, 4 4 (2 ) :170-180. Powers, W.E. 1958. Geomorphology o f the Lake Michigan s h o re lin e . Final re p o rt o f p r o je c t NR387-015, c o n tra c t Nonr-1228(07), Geography Branch, Earth Science D iv is io n , O ffic e o f Naval Reserach, Washington, D.C., 103 pp. P r it c h e t t , P.C. 1974. B l u f f recession on east coast o f Lake Michigan (a b s .). Seventeenth Conference on Great Lakes Research, 1974, A b s tra c t, In te rn a tio n a l A ssociation f o r Great Lakes Research, U n iv e rs ity o f Michigan, Ann Arbor, Michigan, p. 215. 202 Rosen, R.G. 1978. A c lim a to lo g ic a l examination o f November cyclones on the western Great Lakes. Unpublished M.A. research paper, Michigan State U n iv e r s ity , East Lansing, Michigan, 23 pp. Rukavina, N.A. ( e d .) . 1978. Proceedings o f the second workshop on Great Lakes coastal erosion and sedimentation. Hosted by the Hydraulics Research D iv is io n o f the National Water Research I n s t i t u t e and held a t the Canada Centre f o r Inland Waters, B u rlin g to n , O n ta rio , 118 pp. R ussell, R.C.H. and MacMillan, D.H. 1970. Waves and t id e s . Press, Westport, Connecticut, 348 pp. Greenwood S a v ille , T. J r . 1953. Wave and lake le v e l s t a t i s t i c s f o r Lake Michigan. Beach Erosion Board Tecnical Memorandum No. 36, U.S. Army Corps o f Engineers, 94 pp. S aylor, J.H. and Hand, E.B. 1970. Properties o f longshore bars in the Great Lakes. Proceedings o f the Tw elfth Conference on Coastal Engineering, pp. 839-853. S c o tt, I.D . 1942. The dunes o f Lake Michigan and c o rre la te d problems. Michigan Academy o f Science, A rts and L e tte rs 44th Annual Report, pp. 53-61. ________ n .d . U nfinished and incomplete study on sand dunes along Lake Michigan. Unpublished manuscript in f i l e s o f the Michigan Geological Survey, Department o f Natural Resources, Lansing, Mi chi gan. Secretary o f War. 1900. Report o f the board o f engineers on deep waterways. Document No. 149, Part I , 56th Congress, 2nd Session, p. 37. S e ib e l, E. 1972. Shore erosion a t selected s ite s on Lake Michigan and Lake Huron. Unpublished Ph.D. d is s e r ta tio n , U n iv e rs ity o f Michigan, Ann A rb o r, Michigan, 175 pp. ________ , Armstrong, J.M. and Alexander, C.L. 1976. Technical re p o rt on the determ ination o f q u a n tity and q u a lit y o f Great Lakes U.S. s h o re lin e eroded m a te ria l. In te rn a tio n a l Reference Group on Great Lakes P o llu tio n from Land Use A c t i v i t i e s , In te rn a tio n a l J o in t Commission, Windsor, O n ta rio , 292 pp. S e ib e l, E . , Carlson, C.T. and Maresca, J.W ., J r . 1976. Ice ridge form ation: probable co n tro l by nearshore bars. Journal o f Great Lakes Research, 2(2):384-392. S e ib e l, E. and Maresca, J.W., J r . 1975. Recession ra te measurement techniques: user o rie n te d discussion o f the r e l i a b i l i t y o f recession ra te measurements. In Great Lakes Basin Commission, Proceedings o f the Recession Rate Workshop, December 5-6, 1974, Ann A rbor, Michigan, pp. 137-158. 203 Soil Survey S t a f f . 1951. Soil survey manual. U.S. Department o f A g r ic u ltu re Handbook No. 18, U.S. Government P r in tin g O f f ic e , Washington, D.C., 503 pp. Sonzogni, W.C., M onteith, T .J. and S e ib e l, E. 1978. Great Lakes sho re line erosion: a d if f e r e n t p e rsp e ctive . Shore and Beach, 46(1):18-20. Southeastern Wisconsin Regional Planning Commission. 1968. Horizontal and v e r tic a l survey co n tro l in southeastern Wisconsin. Technical Report No. 7, Waukesha, Wisconsin, 155 pp. S ta ffo r d , D.B. 1971. An a e ria l photographic technique fo r beach erosion surveys in North Carolina. Coastal Engineering Research Center Memorandum No. 36, U.S. Army Corps o f Engineers, Fort B e lv o ir , V i r g in ia , 115 pp. S tark, J. 1975. Annotated b ib lio g ra p h y o f g e o lo g ic a l, h y d ro lo g ic a l, s o i l s , and c lim a to lo g ic a l in fo rm a tio n fo r Wisconsin's Great Lakes coastal zone counties ( d r a f t ) . U n iv e rs ity o f WisconsinExtension, Wisconsin Geological and Natural H is to ry Survey, Madison, Wisconsin, 116 pp. S t r ie g l, A.R. 1968. Shoreline and flo o d p la in zoning along the Wisconsin shore o f Lake Michigan. Wisconsin Department o f Natural Resources, D iv is io n o f Resource Development, Madison, Wisconsin, 75 pp. Tanner, W.F. 1975. Beach processes, Berrien County, Michigan. o f Great Lakes Research, 1(1):171-178. Journal ________ ( e d i t o r ) . 1978. Standards f o r measuring s h o re lin e changes. Coastal Research and Department o f Geology, F lo rid a State U n iv e r s ity , Tallahassee, F lo rid a , 89 pp. Thwaites, A.M. 1931. 39:653-654. Recent stream in t e r c i s i o n . Journal o f Geology, _ 1953a. I l l i n o i s shore o f Lake Michigan beach erosion co n tro l study. House Document No. 28, 83rd Congress, 1st Session, U.S. Government P r in tin g O f fic e , Washington, D.C. _ U.S. Army Corps o f Engineers. 1946. Beach erosion study: Lake Michigan shorelines o f Milwaukee County, Wisconsin. House Document No. 526, 79th Congress, 2nd Session, U.S. Government P r in tin g O f fic e , Washington, D.C. 1953b. Racine County, Wisconsin, beach erosion c o n tro l study. House Document No. 88, 83rd Congress, 1st Session, U.S. Government P r in tin g O f fic e , Washington, D.C. 204 1955. C ity o f Kenosha, Wisconsin, beach erosion con tro l study. House Document No. 273, 84th Congress, 2nd Session, U.S. Government P r in tin g O ffic e , Washington, D.C. 1957. Manitowoc County from Two Rivers to Manitowoc, Wisconsin, beach erosion co n tro l study. House Document No. 348, 84th Congress, 2nd Session, U.S. Government P r in tin g O ffic e , Washington, D.C. 1958. Berrien County, Michigan, beach erosion co n tro l study. House Document No. 336, 85th Congress, 2nd Session, U.S. Government P r in tin g O f f ic e , Washington, D.C. 1965. C ity o f Evanston, I l l i n o i s , beach erosion co n tro l study. House Document No. 159, 89th Congress, 1st Session, U.S. Government P r in tin g O f f ic e , Washington, D.C. 1971a. Great Lakes region inve n to ry re p o r t. National Shoreline Study, North Central D iv is io n , Chicago, I l l i n o i s , 221 pp. 1971b. Shore management g u id e lin e s . Study, Washington, D.C., 56 pp. National Shoreline 1971c. Shore p ro te c tio n g u id e lin e s . Study, Washington, D.C., 59 pp. National Shoreline 1972. Great Lakes s h o re lin e damage: causes and p ro te c tiv e "measures. North Central D iv is io n , Chicago, I l l i n o i s , 22 pp. 1973a. Help y o u rs e lf: a discussion o f the c r i t i c a l erosion problem on the Great Lakes and a lt e r n a t iv e methods o f shore p r o te c tio n . North Central D iv is io n , Chicago, I l l i n o i s . 1973b. Section 111 d e ta ile d p ro je c t re p o rt on shore damage a t St. Joseph harbor, Michigan. D e tr o it D i s t r i c t , D e t r o it , Michigan. 1973c. Shore p ro te c tio n manual (3 volume s e t ) . Coastal Engineering Research Center, U.S. Government P r in tin g O f fic e , Washington, D.C. 1974. Section 111 d e ta ile d p ro je c t re p o rt on shore damage a t South Haven harbor, Michigan. D e tr o it D i s t r i c t , D e t r o it , Michigan. 1975a. In te rim re p o rt on Indiana sh o re lin e e rosion: d e ta ile d f e a s i b i l i t y re p o r t. Chicago D i s t r i c t , Chicago, I l l i n o i s . 1975b. P re lim in a ry f e a s i b i l i t y re p o rt on Lake Michigan "shoreline e rosion , Milwaukee County, Wisconsin. Chicago D i s t r i c t , Chicago, I l l i n o i s . 205 ________ 1975c. Guidelines f o r m onitoring shore p ro te c tio n s tru c tu re s in the Great Lakes. Coastal Engineering Research Center Miscellaneous Paper No. 2-75, Fort B e lv o ir , V i r g in ia , 38 pp. ________ 1976. Great Lakes shoreland damage study. D iv is io n , Chicago, I l l i n o i s . ________ 1977. Water resources development by the U.S. Army Corps o f Engineers in Michigan. North Central D iv is io n , Chicago, I l l i n o i s , 118 pp. North Central Upchurch, S.B. 1973. Lake Michigan coastal processes: Leland to Manistee, Michigan. In Michigan Basin Geological Society, Geology and the Environment, Annual F ie ld Conference, pp. 54-66, 204-220. U y l, R.B.D. 1974. The causes and s o lu tio n s to s h o re lin e erosion on Lake Michigan. Honor's th e s is , Lawrence U n iv e r s ity , Appleton, Wisconsin, 73 pp. V a lle jo , L.E. 1977. Mechanics o f s t a b i l i t y and development o f the Great Lakes coastal b l u f f s . Unpublished Ph.D. d is s e r ta tio n , U n iv e rs ity o f Wisconsin, Madison, Wisconsin, 242 pp. Veatch, J.O. and Humphrys, C.R. 1964. Lake term inology. Water B u lle t in No. 14, A g r ic u lt u r a l Experiment S ta tio n and Department o f Resource Development, Michigan State U n iv e r s ity , East Lansing, Michigan, 271 pp. Water Resources S c i e n t i f i c Inform ation Center. 1972. Lake Michigan: a b ib lio g ra p h y . U.S. Department o f the I n t e r i o r , O ffic e o f Water Resource Research, Washington, D.C., 264 pp. Whitney, C.S. 1936. S t a b il iz i n g a Lake Michigan b l u f f . C iv il Engineering, 6(5):309-313; 6 ( 7 ) :469-470 (comment). W h ittle s e y , C. 1867. Fresh-water g la c ia l d r i f t o f the northwestern s ta te s . Smithsonian C o n trib u tio n to Knowledge No. 197, Volume No. 15, Washington, D.C. W ilkin so n , B.H. and Gray, D.H. 1978. The e f f e c t o f changes in b lu ff - f a c e li t h o l o g y on la t e r a l v a r ia tio n s in coastal recession rates (a b s .). Geological S ociety o f America Abstracts w i t h Programs, 1 0 (6 ):287; paper presented a t the North-Central Section, 12th Annual Meeting, Ann A rbor, Michigan. Wisconsin Department o f Natural Resources. 1975. Shore erosion study: coastal zone management development program. Madison, Wisconsin, 12 pp. 206 ________ 1977. Some n o n -s tru c tu ra l a lte rn a tiv e s f o r the reduction o f shore damage. Wisconsin Coastal Management Development Program, Madison, Wisconsin, 11 pp. Wisconsin Sea Grant Program. 1973. Our Great Lakes. Wisconsin, Madison, Wisconsin, 48 pp. ________ U n iv e r s ity o f n .d . High wafer and erosion on the Great Lakes shores. U n iv e rs ity o f Wisconsin, Madison, Wisconsin, 12 pp. Wojta, J.F. 1945. A h is to r y o f the town o f Two Creeks, Manitowoc County, Wisconsin. L i t t l e P r in tin g Company, Madison, Wisconsin, 72 pp. Wooldridge, C.W. 1884. Recent geological changes 1n western Michigan. Popular Science Monthly, 24:826-830. Zumberge, J.H. and Wilson, J.T. 1953. E ffe c ts o f 1ce on shore development. Proceedings o f the Fourth Conference on Coastal Engineering, pp. 201-205.