A}! AERIAL PHOTOGRAPHIC STUDY
OF THE

(31.55% LAKE - SLEEFERG BEAR PGINT AREA
LEELANAU COUNTY, MICHIGAN

Thesis for ”19 Degree OI M. 5.
MICHIGAN STATE UNIVERSITY
Kenneth G. Johnson

1957

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AN AERIAL PHOTOGRAPHIC STUDY
OF THE
GLEN LAKE - SLEEPING BEAR POINT AREA

LEELANAU COUNTY, MICHIGAN

By

KENKETH G. JOHNSON

A THESIS

Submitted to the School of Science and Arts of Michigan
State University of Agriculture and Applied Science
in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE

Department of Geology

1957

ABSTRACT

An aerial photographic study of the Glen Lake-
Sleeping Bear Point area in Leelanau County, Michigan
shows that the area includes a horseshoe-shaped depres-
sion flanked on the west by a large dune complex.

The depression is divided into four parts on the
.basis of t0pographic configuration and origin of the
features present. The divisions are:

l. The portion of the depression occupied by
Glen Lake.

2. The Day Hills which dominate the west cen-
tral portion of the depression.

3. A low, flat area at the northern edge of
the depression.

4. Morainic hills which rim the depression on
the east, south, and southwest.

The southern third of the dune complex is a plateau
which has develOped on the northwestern end of the mor-
aine extending northwest from the southwestern side of
Glen Lake. Sand, which forms a high percentage of the
material in the moraine, is swept northeast into an area
of accumulation. The lee lepe of the dune complex is

encroaching on the Glen Lake depression.

11

ACKNOWLEDGMENTS

The writer wishes to express his thanks to Miss
Helen M. Martin of the Geological Survey Division, Mich-
igan Conservation Department, for suggesting the problem;
to Mr. William L. Daoust, State Geologist, for his cooper-
ation in making the aerial photos available; to Mrs. Jane
E. Smith, Michigan State University, for her guidance
. and helpful criticisms during the pursuance of the study;
to Dr. H. B. Stonehouse, Dr. W. A. Kelly, and Dr. J. W.
Trow, all of Michigan State University, for reading the
manuscript and suggesting suitable changes; to Mr. Richard
Ernst for aid in obtaining field elevations; and to D.

Nancy Johnson for typing the manuscript.

111

TABLE OF CONTENTS

INTRODUCTION

THE

Nature and Purpose of Study
Location and Extent of Area

Methods

GLEN LAKE DEIRESSION
Glen Lake

The Day Hills

The Bar Area

The Moraine Surrounding the Depression

SLEEPING BEAR DUNES

General

The Plateau and Associated Dunes
The Area of Lecumulation

Origin of the Unnes

RECOMMENDATIONS FOR FURTHER STUDY

BIBLIOGRAPHY>

iv

11
14

15
15
17
22
26

29

32

Figure

1.

FIGURES

Index map showing location of the thesis

area 0

Photograph of the west arm of Glen Lake.

Photograph of the west end of the bar area.

Photograph of the Crystal River.

Photograph of the lee slope of the Sleep-

ing Bear dunes.

Photograph of the Sleeping Bear and the

southern portion of the plateau.

Photograph of a large blowout on the east

side of the plateau.

Photograph of exhumed cedars in a blowout
on the east slope of the area of accumula-

tion.

Photograph of blowout in area of accumula-

tion.

Page

10

12

14

16'

2O

25

26.

PLATES

Plate
I Form line map showing the topography of the
Glen Lake depression.
II Map showing vegetation cover and road system
of the Glen Lake depression.
III Tepographic map of the Sleeping Bear sand dunes.

vi

INTRODUCTION
Nature and Purpose of the Study

Extensive areas of sand dunes are found along the
south and east coasts of Lake Michigan. As far north
as Manistee these dunes are in the form of long fore-
dune ridges backed by blowouts in dunes built previous
to the present stage of dune formation. The older dunes
evolved during the various glacial and early post-
glacial lake stages of the Lake Michigan Basin. They
were subsequently anchored by vegetation and are now
being dissected by wind erosion. The foredune ridges
are a result of the action of waves and currents which
deposit sand on the beaches, and onshore winds which
sweep the sand from the beach and deposit it in long
ridges paralleling the coast.

Sand deposits along the northeast shore of Lake
Michigan are, in general, not found in the forms which
are characteristic of those on the southeast shore.
According to Leverett (1915), the Manistee moraine of
the Port Huron morainic system wraps around the western
end of prominent ridges which are oriented transverse

to the shore, and appear as headlands along the north-

east shore of Lake Michigan. Glacial ice readvanced
into the lowlands between these transverse ridges and
consequently the moraine makes a series of loops as it
crosses the lowlands between the ridges. The alterna-
tion of lowlands separated by morainic ridges gives this
part of the Lake Michigan coast an interrupted character
which prevents extensive linear development of sand
dunes parallel to the coast.

An interesting aeolian depositional feature of
the northeastern Lake Michigan coast is the perched dune.
Some of these dunes rest on Nipissing and Algonquin
beaches and are in an elevated position relative to the
present lake level. Others are "perched" on high mor-
ainic bluffs adjacent to the shore. Fuller (1918) des-
cribed the perched dunes of the Beaver Islands and South
Fox Island. Dow(l938) investigated the origin of the
perched dunes of the Manistee Moraine. Both writers
briefly described the dunes of Sleeping Bear Point in
southwest Leelanau County. In 1926 Waterman described
the Sleeping Bear dunes in his discussion of the ecology
of the Glen Lake region.

The primary purpose of the present study is to map
and describe the Sleeping Bear dunes and to discuss their
origin and evolution. In addition, the Glen Lake depres-
sion is described because of its close association with

the dunes.

Location and Extent of
the Area

The Glen Lake-Sleeping Bear Point area is located
in southwest Leelanau County of Michigan's lower penin-
sula. It is approximately five miles north-northeast
of the town of Empire and twenty miles northwest of Tra-
verse City.

The area is bordered on the west by Lake Michigan,
on the north by Sleeping Bear Bay and Manitou Passage,
and on the east and south by morainic hills which rise

abruptly from the shores of Glen Lake.

1"
NORTHPORT

0 1 /
/

EUPIRE

EELANATG' 66.-

MICHIGAN
LOCATION MAP

FIG. I

Methods

In the pursuance of this study, an emphasis was
placed on laboratory work in the form of aerial photo-
graphic interpretation of the area and reliance on aerial
photogrammetry for all mapping.

The photographs used were provided by the Conser-
vation Department of the State of Michigan. They were
taken with an 8.25 inch focal length camera at a flying
height of 10,788 feet; the resulting scale being 4 inches
to the mile.

At the beginning of the study a thorough interpre-
tation of the photography was made. By this means, the
physiography of the area was studied and specific loca-
tions were outlined where field reconnaissance would be
necessary for an understanding of their relation to the
gross physiography.

Since no large scale base maps of the Glen Lake-
Sleeping Bear Point area were available, the next step
was the compilation of a planimetric base map from aerial
photography. Abrams mechanical triangulators were used
to provide horizontal control by radial line plot. A
vertical sketchmaster was used to transfer planimetric
detail from the photos to the base sheet. The resulting
map was compiled at the same scale as the photographs.

One week was devoted to a field reconnaissance of

the area. At this time elevations were taken with a

Wallace and Tiernan barometric altimeter.

After the reconnaissance was completed, a Fairchild
Stereocomparagraph was used to sketch formlines on the
base map of the Glen Lake area. Although the formlines
are not accurate enough to be considered contours, it
is felt that they give a realistic picture of the topo—
graphy of the Glen Lake depression. The same base was
used to compile a map showing the road system and vege-
tation cover of the Glen Lake area.

The Sleeping Bear dune area was contoured with the
stereocomparagraph after the effects of tip and tilt
were removed from the vertical control point parallax
readings by means of correction graphs. McNeil (1950)
states that the smallest contour interval which can be
used in contouring with the stereocomparagraph is l/ZSOth
of the flying height of the aircraft which took the
photography. The smallest usable contour interval in
the case of the photography used in this study was As

feet.

THE GLEN LAKE DEPRESSION

During the Wisconsin stage of the Pleistocene epoch
the Lake Michigan Basin was occupied by glacial ice.
Changes in climate and hence nourishment for the ice

sheet caused the lobe alternately to extend southward

and retreat northward in the basin.

Beach lines above the present shore of Lake Michi-
gan mark the levels of the ice-marginal lakes which oc—
cupied the basin at this time. The earliest of these lakes
has been called Lake Chicago. The level of Lake Chicago
rose and fell with advance and retreat of the tongue of
ice and the consequent uncovering or covering of drain-
age outlets of higher or lower elevation. Although in
its later stages Lake Chicago extended northward nearly
to the Straits of Mackinac, the beaches which it built
have been preserved only in the southern half of the
basin.

The ice eventually retreated north far enough to
allow the union of the waters of the Michigan, Superior,
and Huron Basins. The extensive lake which resulted
has been called Lake Algonquin.

The history of the Glen Lake depression prior to
the formation of Lake Algonquin is obscure. The hills
enclosing the depression and the Day Hills in the west
central portion of the depression are part of the Menis-
tee moraine. Bough (1953) correlates the Manistee mor-
aine with the Mankato till of northeastern Wisconsin.
Radiocarbon dating indicates that Mankato maximum glacia-
tion occurred 11,000 years ago (Flint and Deevey, 1951).

During Algonquin time, the waters of this large ice—

marginal lake invaded the Glen Lake depression. The

entire depression, with the exception of the hill mass
in the west central portion, was covered by the waters
of a bay. "The highest Lake Algonquin stage was term-
inated either by a downcutting of one of its southern
outlets or by diversion of its discharge to a new, low-
er outlet made available by recession of the glacial

ice dam (Hough, 1953)." A beach below that of Lake Al-
gonquin marks the level of Lake Nipissing in the north-
ern Lake Michigan Basin.

The Glen Lake depression may be divided into four
distinct parts on the basis of both topographic config-
uration and origin of the features found there. The
divisions are:

l. The portion of the depression occupied by
the waters of Glen Lake.

2. The Day Hills which dominate the west cen-
tral portion of the depression.

3. The low, generally flat area which fringes
Sleeping Bear Bay at the north edge of the
depression.

4. The morainic hills which rim the depression

on the east, south, and southwest.
Glen Lake

Two thirds of the area within the depression is

occupied by Glen Lake. The lake is divided into an east

arm and a west arm by a narrows where the moraine which
borders the lake on the south lies in close proximity

to the Day Hills in the west central portion of the de-
pression. The east arm, the larger of the two, is near-
ly circular in outline and has an area of approximately
seven square miles. The west arm extends northwest
from the narrows for a distance of two and one quarter
miles and measures one mile across at its widest point.

The only stream flowing into the lake is a small
creek which rises on the slepe of the moraine one half
mile south of the east arm. The waters of Glen Lake
drain north through Fisher's Lake and then to Sleeping
Bear Bay via the Crystal River.

The level of Glen Lake, while field work was being
conducted in August of 1957, was 594 feet above sea level.
The level of Lake Michigan is variable around 578 feet
above sea level, depending on the season and amount of
precipitation. Scott (1920) found the Glen Lake level
to be 17 feet above that of Lake Michigan.

The waters of Glen Lake are held in this elevated
position by a succession of Algonquin baymouth bars
which occupy the northeast fringe of the depression.

The Lake Algonquin level is represented in the de-
pression, at an elevation of 615 feet above sea level,
by a beach which closely follows the present shore of

Glen Lake. The beach is best develOped around the east

arm of the lake where wave action was undoubtedly more
vigorous than in the smaller, more protected, west arm,
and when viewed on photography or in the field is obvious
on the northeast and southeast shores. Roads have been
built on the beach along the northwest, northeast and
southeast shores of the east arm of Glen Lake, and along
the north and west shores of the west arm. One mile

south of Glen Arbor, State Highway 22 crosses a triangular

shaped remnant of the beach.
The Day Hills

A high, densely forested hill mass is situated in *
the west central portion of the depression. The hills
rise to an elevation of 953 feet above sea level three-
quarters of a mile southwest of Glen Arbor. The mass
is highest along its northern edge where a bluff slopes
precipitously to the low area bordering Sleeping Bear
Bay. The south side slopes less steeply to the west.
arm of Glen Lake. A spur projects west from the north—
west side of the mass, decreasing in width as it approach-
es the lee side of the Sleeping Bear dune complex. The
bluff which characterizes the north slope of the Day
Hills extends west along the north side of the spur.

The bluff is the result of the erosive action of

the waves of Lake Algonquin. The lower slope was sub—

jected to the full force of waves which developed in
catchment areas far out in the lake. The wave—cut bluff
which resulted was probably not much steeper than that
which we find today because a dense vegetation cover
has prevented erosion and consequent destruction of its
face. I

When the waters of Lake Algonquin invaded the Glen
Lake depression, the Day Hills became an island. At
this time two channels provided access to the depres-
sion, one, approximately two miles wide, east of the
hill mass and one west of the spur. The western chan-
el is now covered by the Sleeping Bear dune complex.

Its extent, therefore, is unknown.

 

 

Figure 2. View of the west arm of Glen Lake from the
area of accumulation.

10

The Day Hills are covered by a dense deciduous for-
est. The only open areas in this forest are the grass—
covered remains of a golf course which was constructed
on the D. H. Day estate some years ago. A network of

unpaved roads provides access to the area.

The Bar Area

A succession of Algonquin bars parallels the shore-
line of Sleeping Bear Bay and constitutes a record of
the withdrawal of the waters of Lake Algonquin from the
Glen Lake depression. The bars extend from the foot of
the moraine which borders the depression on the east,
westward to Sleeping Bear Point. This low, generally
flat area is widest immediately north of the east arm
of Glen Lake, narrows to less than half a mile Just west
of Glen Arbor, and widens slightly westward toward the
dunes covering Sleeping Bear Point.

The eastern third of the bar area is poorly drained,
with small patches of marshy ground, some of which are
covered by a dense growth of tamarack. This area con-
sists of baymouth bars built during the time the waters
of Lake Algonquin occupied the depression and during
the lowering of the lake to Nipissing level.

The western two-thirds of the bar area is slightly
higher, and has had a somewhat different origin than

the east third. Here bars were not built in the shallow

ll

entrance to a bay, but adjacent to a steep bluff which
was being cut by wave action. They are now protected
from wind erosion by a covering of vegetation, and the
high moraine and sand dunes which shut out the prevail—-
ing southwest winds. In places, however, blowouts of
limited extent have developed in the west third of the
bar area. Gravel has been uncovered in some of these
blowouts and probably represents coarse bar material
which had been eroded from the bluff. The overlying
sand was deposited in low dune ridges which backed the
beach as it moved lakeward during the lowering of lake

Algonquin to Nipissing level.

 

 

 

 

Figure 3. View of the west end of the bar area from the
area of accumulation.

12

The wave action which formed the bluff along the
north side of the hill mass and spur was also respons-
ible for the formation of a wavecut terrace at the base
of the bluff. Although the terrace extends from a point
approximately one half mile southwest of Glen Arbor west-
ward nearly to the east slope of the dune complex, it
is best seen in its west half where the land has been
cleared and orchards planted. The terrace is composed
of three levels. The highest is 605 feet above sea lev-
el, the lowest approximately 600 feet. Just east of the
road junction where State Highway 109 turns east toward
Glen Arbor, the combined width of the three levels is
approximately 100 yards.

At the east edge of the bar area the Crystal River
flows in broad meanders northwest toward Sleeping Bear
Bay. The course of the stream is controlled by the
orientation of the bars.

The western third of the bar area is covered by
stands of evergreens, poplars, and grass. The eastern

two-thirds is densely forested with hardwoods.

13

 

 

 

Figure 4. View of the Crystal River east of Glen Arbor

The Moraine Surrounding the Depression

The moraine which encloses the Glen Lake depression

forms a bluff where it extends southwest along the east

shore of Sleeping Bear Bay. At Prospect Hill the mor-

aine turns south and closely follows the shore of the

«east arm of Glen Lake. South of the west arm of Glen

Imake the moraine lies farther from the lake shore, but
is closer to the shore where it trends northwest toward

tdoe Sleeping Bear dunes. A'gravel plateau, partially

Covered by sand dunes, composes the northwest end of the

IDCJraine. This plateau constitutes the southern third

(31‘ the Sleeping Bear complex.

14

THE SLEEPING BEAR DUNES

General

Dow (1938) states that of 20 sections in Glen Arbor
township, 10 are composed of sandy till. Leverett (1911)
records a similar high percentage of sand in his soil
studies of townships of western Benzie County. Accord-
ing to Dow some of the morainic bluffs along the north-
ern Lake Michigan shore are composed of such a high per-
centage of sand that early geologists described them as
wind-blown deposits. The moraine which extends north-
west toward Sleeping Bear Point from the southwest side
of Glen Lake has this characteristic high percentage
of sand. The composition of the moraine and its ex-
posure to the prevailing southwest winds provide two
requisites which are essential for the development of
aeolian activity: a source of material and wind of gen-
erally constant direction and velocity sufficient to
move the material. The presence of these requisites
on the west flank of the Glen Lake depression has re-
sulted in the formation of the Sleeping Bear dunes.

The Sleeping Bear dunes border Lake Michigan south
from Sleeping Bear Point for a distance of six miles.

The dune complex is widest in its northern half where

15

its longest east-west dimension measures a mile and a
quarter. It becomes narrower southward until it "pinch-
es out" against the shore just north of North Bar Lake.
The area of aeolian activity is referred to as a
complex because it consists of two closely related, but
distinctly separate parts. The southern third of the
complex is a gravelecapped plateau which lies an aver-
age of 325 feet above the level of Lake Michigan. Por-
tions of the plateau are covered by sand dunes. An ex-
tensive sand accumulation lies north and northeast of
the plateau. The accumulation is encroaching on the

Glen Lake depression to the east-

 

 

 

Figure 5. View of the lee slope of the Sleeping Bear
Dunes from the top of the spur west of the
Day Hills.

16

The Plateau and Associated Dunes

The morainic plateau which constitutes the south
third of the area of aeolian activity is triangular in
plan view. The longest side of the triangle trends
north-south along a precipitous bluff which follows the
Lake Michigan shore. The shorter sides of the triangle
are approximately equal in length and trend northeast
and southeast from the ends of the bluff.

The northwest portion of the plateau consists of a
surface of lag gravel and cobbles. The material shows
the wide range of composition and size which is charac-
teristic of moraines. In this area the finer material
has been carried away by the action of the wind. Cob—
bles and gravel which remain have been polished and fac-
eted by the bombardment of wind-blown sand and many ex-
cellent ventifacts have developed. Dow(1940)'has des-
cribed the ventifacts of the Sleeping Bear dunes. He
concluded from a study of the orientation of the wind-
faceted cobbles that the prevailing wind is from the-
southwest.

The morainic bluff which marks the west edge of the
plateau ranges from 320 to 375 feet high. It rises from
the narrow beach at its base at an angle of approximately
32°near its south end. The slope angle increases to

approximately 3S’near the north end. The bluff is cut

17

by numerous gullies, a few of which extend half way
down the bluff face. Most of the gullies, however, ex-
tend approximately one quarter of the way down to the
beach. The gullies providaigégégggays for sand which
blows up the bluff from sand lenses farther down the
slope. Long, low ridges of loose sand extend northeast
onto the plateau from the tops of the larger gullies.
The material which gaine:égggg9 to the plateau through
the smaller gullies generally is not of sufficient quan-
tity to accumulate in elongate ridges at the west edge
of the plateau. This is not to say, however, that in
the course of time considerable quantities of sand do
not move from the bluff face to the plateau surface via
the smaller gullies.

The accumulations of sand in the gullies and the

sand ridges which extend onto the plateau from their
upper ends make the gullies the most obvious channels
by which sand gains CEEEE) to the plateau. However,
sand does move up the bluff along its entire length.
A low ridge of sand extends along the top of the bluff.
It ranges from a few to several feet in height, and ex-
hibits a “smoking crest". Here the sand which has mov-
ed up the bluff comes to rest temporarily before it be-
gins its movement northeastward across the plateau.

Although the velocity of the wind which blows on-
shore from Lake Michigan meet‘éfitImeé“BE“great, it is

18

not likely that much, if any, material is blown up the
bluff from the beach. The force of the wind decreases
noticeably from the top of the bluff to the beach. Here,
of course, the velocity requirement for transportation
of sand up the bluff is greatest. Dow (1938) thinks

that it is probable that some sand does move up the bluff
from the beach, but very slowly..

At the top of the bluff, approximately midway be-
tween its north and south ends, an isolated sand accumu-
lation rises 70 feet above the plateau surface. This rem-
nant of what was once a larger dune is called the Sleeping
Bear. After the recession of the glacial ice from the
Michigan Basin, isolated stands of cedars were able to
gain a foothold on the moraine west of the Glen Lake de-
pression. One of these stands grew at the present loca-
tion of the Sleeping Bear with some of the trees reach-
ing a height of over 35 feet. Sand moving up the bluff
and across the plateau was trapped by the cluster of
vegetation. .As the sand deposit grew the cedars were
buried and sand which blew over the crest of the dune
fell into a wind shadow on its lee side. It is probable
that the dune did not develop at the edge of the bluff,
but that the bluff at that time lay farther to the west.
The constructive phase of the development of the Sleep-
ing Bear may have ended because of a decrease in wind

velocity or a shift in wind direction. Whatever the

19

reason for the cessation of deposition, it is probable
that vegetation stabilized the dune at this time.

The destructive phase of dune development was ini—
tiated when a prevailing southwest wind pattern was es-
tablished. As the wind blew against the eXposed face '
of the dune a hollow was formed. Sand blown from the
hollow accumulated on its leeward rim. The Sleeping
Bear is now a blowout surrounding the cedars which have
been exhumed at its center. The north and east slopes
are covered by arborvitae, calamovilfa, sand cherry,

and grasses (Dow, 1938).

 

 

 

 

.ngure 6. View of the plateau and the Sleeping Bear dune
from the southern end of the Sleeping Bear dune
complex.

20

-Sand dunes occupy the eastern and southern por-
tions of the plateau. The highest dunes are found at
the south end where they rise to an elevation of over
1050 feet above sea level. Some dunes along the east
edge of the plateau are over 950 feet above sea level.
The prevailing southwest winds of the area are reflected
in the large number of blowout and elongate blowout

dunes which trend northeast across the plateau surface.

 

 

 

 

 

Figure 7. View of a large blowout on the east side of
the plateau.

Although large dunes are found on the east and south
portions of its surface, the plateau, viewed in total

aspect, is a source area rather than an area of deposition.

.The Area of Sand Accumulation

. The northern two-thirds of the Sleeping Bear dune
complex is occupied by a massive sand accumulation which
is moving east into the Glen Lake depression. Dow (1938)
refers to these deposits as semi—perched dunes. This 1i§33
portion of the complek is an area of dominant depositiogf
The activity here contrasts with that on the.plateau ’.
'to the south where sand is being removed and blofin‘north-
east into the area of accumulation.The prevailing
southwest winds have removed sand from the northeast
side of the plateau and deposited it in a broad,§ratheri
elongate mass which trends northeast from the platggu.i
_ Several extensive depressions on the,plateau immediately
windward of the sand accumulation have been scourgdaby
wind action.

The highest elevations in the area of accumulation
are found in its southeast portion where one dune rises
to over 850 feet above sea level. Elevations decrease
,gradually northward toward Sleeping Bear Point. They
decrease more abruptly northwestward to a low area,

2300 yards long and 650 yards wide, which borders Lake
Michigan. The elevation of this low area averages 25
feet above the level of Lake Michigan with several de—

jpressions less than 20 feet above lake level. This

22

area was covered by the waters of Lake Algonquin. It
is probable that the depressions represent terraces and
beaches of Lake Nipissing (Waterman, 1926).

Aerial photos show a concentration of blowout dunes
on the plain and on the slopes which rise from the plain
toward the east side of the area of accumulation. These
blowouts, like those on the plateau, trend northeast.
Many of them contain cedar stands which have been ex-
humed by the action of the wind. The.material from the
'blowouts has been transported northeast toward Sleeping
Bear Point and has collected in a broad dune, the tOp
of which rises to over 700 feet above sea level. The
vigorous action of the wind on this exposed dune is ex-
hibited in the broad wind ripples which trend northwest
across its surface and in the rapid burial of poplars
on its lee slope. A narrow, somewhat lower dune extends
northeast from the main mass.

The northwest side of Sleeping Bear Point consists
of a shallow, bowl-shaped depression approximately 200
yards in diameter. The dunes mentioned above form the
southwest and southeast flanks of the depression, and
a low dune ridge separates it from the beach which bor-
ders Lake Michigan on the northwest. The floor of the
depression is at about the same level or slightly be-

low the level of Lake Michigan. This relationship to

23

Lake Michigan along with the internal drainage atten-
dant with its configuration has caused the depression
to be moist throughout most of the year and even to
support a small pond during periods of heavy rain and
high lake level. Grasses, and some poplars and scrub
pine cover the floor of the depression.

The high sand ridge which constitutes the east
edge of the area of accumulation is moving east into
the Glen Lake depression. Stands of hardwoods along
the west side of the depression are being buried by
the sand. Fence lines erected a relatively few years
ago now disappear into the advancing lee slope of the‘
sand mass. Approximately a mile and a quarter south of
Sleeping Bear Point, a road, which parallels the east
edge of the dune complex, has been cut off by the en-
croaching sand. The lee side of the area of accumula-
tion has a lepe of approximately 32: the characteristic
angle of repose of dry, loose sand.

Two large blowouts lie along the east edge of the
sand mass. The larger of the two, approximately half
way between Sleeping Bear Point and the south end of
the area of accumulation, lies at the northeast and of
a longitudinal dune which extends northeast from the pla-
teau. The smaller blowout lies immediately to the north

in an area which has been stabilized by vegetation.

24

Cedar stands buried by the advance of the sand, have

been exhumed at the centers of the blowouts.

 

 

 

 

 

 

Figure 8. View of exhumed cedars in a blowout on the
east slope of the area of accumulation.

Throughout both the area of accumulation and the plateau
vegetation has been able to gain a foothold in areas
which are protected from the wind. Some of the patches
of grass, vines, and poplars are now situated in expos—
ed locations and must have evolved at times when they
were more protected. In places the vegetation has sta—
bilized the dunes. Thin layers of organic material un-
covered in some of the blowouts indicate previous per—

iods of dune stabilization.

25

 

 

 

Figure 9. View of a blowout in the area of accumulation.

Origin of the Dunes

Fuller (1918) and Dow (1938) have offered theories
of origin to explain the development of the Sleeping
Bear dunes.

Fuller divided the dunes of northern Lake Michigan
into two groups, lacustrine dunes, and terrestrial dunes.
He considered the lacustrine dunes as: "being formed from
sand thrown upon the shore by the waters and then caught
up by the wind, carried inland, and piled in character-

istic mounds and ridges." The lacustrine dunes are of

26

two types: beach dunes develOped on the existing beach;
and perched dunes developed on substrata elevated some
distance above the beach. He envisaged terrestrial dunes
as being: "formed from sandy material deposited by the
action of ice and water about the margin of the Pleisto-
cene ice sheet and afterwards worked over by the wind".
He classifies the dunes of the Sleeping Bear complex as
terrestrial in origin. Although the findings of this
study generally support Fuller's designation of the Sleep-
ing Bear dunes as terrestrial dunes, the divisions of

the classification proposed by him are so broad that

they have little practical value.

Dow, after studying the perched dunes found along
the western edges of the Manistee moraine, prOposed the
following arbitrary classifications:

Type I - Sand of beach origin—--accumulation
due to wind action.

Type II - Sand of beach origin--—accumulation
due to wind action accompanied by
shore recession.

Type III- Sand derived from morainic drift.

Type IV - Sand of combined beach and morainic
origin.

Dow includes the Sleeping Bear dunes under his Type IV

classification.

.27

The observations made during the present study war-
rant a theory of origin essentially the same as that of-
fered by Dow. The only point of possible disagreement
would be whether or not sand is transported from the
beach to the plateau via the high, steep bluff at the
southwest edge of the complex. Even this point is a
purely academic one, for Dow pointed out that he consid-
ered the rate of sand movement from the beach to the
plateau to be very slow. He clearly states that the
Type IV perched dunes of the northern Lake Michigan shore
are composed of material derived mainly from the sandy
moraines of the area.

The origin and development of the Sleeping Bear
dune complex may be summarized as follows: The high
percentage of sand in the moraine which extends north-
west from the southwest side of Glen Lake provides a
source of material. The prevailing southwest wind which
strikes Sleeping Bear Point and the shore south of the
point is of sufficient velocity to act as a transporting
medium.

Hind blowing onshore from Lake Michigan has swept
sand from the plateau and deposited it over a broad area
to the northeast. Parts of the plateau are now capped
by a surface of lag-gravel. Lenses of sand are exposed

on the face of the bluff which marks the west edge of

28

the plateau. Gullies extending down the bluff serve

as accessways through which sand moves to the plateau
surface. Long ridges of sand extend from the upper ends
of the gullies onto the plateau. The wind also trans-
ports sand up the bluff along its entire length. This
sand accumulates at the top of the bluff in a low ridge.
It is improbable that the wind has a velocity sufficient
to transport sand from the beach to the plateau via the
bluff face.

Sand dunes cover much of the plateau surface. These
deposits consist of material which is migrating north-
east across the plateau and which will eventually become
a part of the sand mass in the area of accumulation.

The plateau and the bluff at its western edge constitute
the source area of the Sleeping Bear dune complex.

The northern two-thirds of the complex is an area
of deposition. The east slope of the sand mass in this
portion of the complex is advancing eastward into the

Glen Lake depression.

RECOMMENDATIONS FOR FURTHER STUDY

Aerial photographic interpretation provides a means

of studying the surface features of the land in a frac-

29

tion of the time required for a comparable ground survey.
During World War II and the Korean Conflict the armed
forces were quick to recognize the value of aerial photo-
graphy for rapid evaluation of unfamiliar terrain. Photo-
graphic interpretation was developed to a high degree

by trained specialists.

The peacetime applications of photographic inter—
pretation are now being developed. For example, the dis-
tinct patterns shown on aerial photography by vegetation
cover, and glacial and geomorphic formations make these
features particularly adaptable for aerial survey. Pre-
cise interpretation is dependent on a thorough understand-
ing of the forms studied and field work may be required
where a detailed evaluation is made.

Accurate planimetric and topographic maps may be
compiled by photogrammetric methods more rapidly than by
ground survey. However, characteristics of the available
photography and capabilities of the instruments used to
compile the maps place limitations on the tOpographic de-
tail which may be shown on the maps. The flying height
of the photography used in this study and the relatively
simple instrument used for contouring allowed a minimum
contour interval of 45 feet. Consequently the blowouts
in the dune complex do not show on the t0pographic map

of the Sleeping Bear dunes.

30

During every aerial photographic survey, problems
are encountered and limitations are recognized. Improv-
ed techniques and methods consequently evolve. It is
suggested that aerial photographic interpretation in its
present stage of development offers an accurate, rapid,
relatively inexpensive means of studying the surface
features of the land, and that each survey which is con-
ducted contributes to the overall development of photo-

graphic interpretation.

31

BIBLIOGRAPHY

Dow, K. W. (1938) The origin of perched dunes on the
Manistee moraine: Papers Mich. Acad. Sci., Arts,
and Letters, Vol. 23, pp. 427-440.

---------- (1940) Some examples of ventifacts from
Sleeping Bear Point, Leelanau County, Michigan:
Papers Mich. Acad. Sci., Arts, and Letters, Vol.
25, PP- A73-476.

Flint, R. F. and Deevey, E. 3., Jr. (1951) Radiocarbon
dating of Late-pleistocene events: Am. Jour. Sci.,
Vol. 249, pp. 257-300.

Fuller, G. D. (1918) Some perched dunes of northern
Lake Michigan and their vegetation: Trans. Ill.
Acad. Sci., Vol. 11, pp. 111-122.

Hough, J. L. (1953) Pleistocene chronology of the Great
Lakes region: 0. N. R. project report, 108 pp.

Leverett, F. (1911) Surface geology and agricultural
conditions of the southern peninsula of Michigan:
Ann. Report Mich. Geol. and Biol. Survey, Pub. 9,
Ser. 7, 144 pp.

Leverett, F. and Taylor, F. B. (1915) The Pleistocene of
Indiana and Michigan: U. S. Geol. Survey, Mon. 53,
529 PP.

McNeil, G. T. (1950) ABC‘s of photogrammetry, part.1,
fundamentals: published by author, 125 pp.

Scott, I. D. (1920) Inland lakes of Michigan: Ann. Rep.
Mich. Geol. Survey, Pub. 30, Ser. 25, 383 pp.

Waterman, W. G. (1926) Ecology of Glen Lake and Sleep—

ing Bear region: Papers Mich. Acad. Sci., Arts, and
Letters, Vol. 6, pp. 351—375.

32

 

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