VITA Donald Bruce Cann candidate for the degree of Doctor of Philosophy Dissertation: A Study of the Genesis of a Gray Brown Podzolic - Podzol Intergrade Soil Profile in Michigan Outline of Studies Major Subject: Soil Science Minor Subjects: Geology, Botany Biographical Items Born, November 2 6, 1909? Yarmouth, Nova Scotia, Canada Undergraduate Studies, N. S. Agricultural College 1927-29 McGill University 1929-31 Graduate Studies, McGill University 1938-1+0 Michigan State College 1952-5*4Experience: Farming 1931-3*4-? with Canada Department of Agriculture as Student Assistant 193*4— 36, Graduate Assistant 1936-*fO, Agricultural Assistant 19*4-0-*+3 ? Member of Canadian Armed Forces 19*f3-*f-5? with Canada Department of Agriculture as Agricultural Scientist 191+5-^6 , Soil Specialist 19*4-6-50 and Agri­ cultural Research Officer 1950- Member of the Society of the Sigma X i , the Agricultural Institute of Canada, the Nova Scotia Institute of Agrologists. A STUDY OF THE GENESIS OF A GRAY BROWN PODZOLICPODZOL INTERGRADE SOIL PROFILE IN MICHIGAN By Donald Bruce Cann AN ABSTRACT Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Soil Science Year Approved, 195^ ABSTRACT A modification of the resistant mineral method used by Marshall and Haseman was applied to a study of the genesis of a Gray Brown Podzolic-Podzol intergrade in Michigan. Changes introduced in the method were (1) the use of quartz, instead of zircon, as the resistant refer­ ence mineral, (2) the determination of quartz with a Gei­ ger counter x-ray spectrometer and (3) the use of the coarser fractions of the soil. Quartz was determined quantitatively on the coarse, fine and very fine sand fractions of the soil, using a Norelco Geiger counter x-ray spectrometer. The method developed eliminates the use of an internal standard used by previous workers and is time saving. It was found that the choice of a quartz standard was important. Calculation of the volume of parent material neces­ sary to produce one cubic centimeter of the present hori­ zons gave a volume change factor for determining the original volume and weight of each horizon. The gains and losses for the solum were thus computed. Results show that about 85 percent of the soluble material originally present has been removed from the profile. There was a total loss in weight of the solum, but a 20 percent gain in volume which occurred largely in the Al p , Agp and Bp horizons. Marke€ increases in organic matter in the Bp and in organic matter and clay in the B21QBP seem to indicate that both of these are illuvial horizons. Losses of soluble material, silt and clay and the small volume change of the B-^Qpp horizon, compared with the horizons above and below, give support to the conclusion that it is an eluvial horizon and that two processes are occurring simul­ taneously during profile development. A STUDY OF THE GENESIS OF A GRAY BROWN PODZOLICPODZOL INTERGRADE SOIL PROFILE IN MICHIGAN ByDonald Bruce Cann A THESIS Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Soil Science 195^ ProQuest Number: 10008272 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 10008272 Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346 ACKNOWLEDGMENTS The author id.shes to express his sincere thanks and appreciation to Dr. E. P. Whiteside for his in­ spiration, guidance and unfailing interest throughout the course of this investigation. The author is indebted to Dr. K. L. Cook who read the manuscript and o'ffered many helpful suggestions. He is also indebted to Mr. Don Van Farrowe of the Michigan Industrial Health Laboratory, Michigan Depart­ ment of Health, Lansing, Michigan, for permission to use the Geiger counter x-ray spectrometer. He also wishes to extend his thanks to Dr. S. G. Bergquist and the staff of the Department of Geology, Michigan State College, who provided the quartz samples used in this study. He is deeply appreciative of the help and advice offered at all times by staff members of the Soil Science Department and the constructive criticism and sugges­ tions made by his fellow students. TABLE OF CONTENTS I. INTRODUCTION II. REVIEW OF LITERATURE 1 3 III. APPARATUS AND MATERIALS A. The Geiger counter X-ray Spectrometer 18 B. Soil Profile Investigated 19 IV. EXPERIMENTAL PROCEDURE A. Preliminary Investigation 20 B. Preparation of the Soil Sample 22 C. Analytical Determinations 23 V. RESULTS AND DISCUSSION A. Results of Preliminary Studies 26 B. The Determination of Quartz in Soil Fractions 28 C. Results of Physical and Chemical Analyses 3^ D. Mineralogical Studies 36 VI. APPLICATION OF RESULTS TO THE STUDY OF SOIL DEVELOPMENT A. Method of Calculating Data ^fO B. Results and Discussion *+1 C. Suggestions for Further Study 52 VII. CONCLUSIONS 60 VIII. BIBLIOGRAPHY 62 LIST OF TABLES TABLE I. Mean Peak Heights of Size Fractions II. Significance Between Mean Peak Heights of Same Size Fraction Run on Different Days III. Significance Between Mean Peak Heights of Different Size Fractions on the Same Day IV. V. VI. VII. VIII. IX. X. XI. Percent Quartz in Soil Sand Fractions Revised Percent Quartz in Soil Sand Fractions Quartz in Sand Fractions as Percent of Total Soil Percent Feldspars in Sand Fractions Composition of the Marietta Loam Profile, Excluding Gravel Percent Heavy Minerals in Sand Fractions Volume Change Factors for the Mariette Loam Original and Present Constituents in the Pro­ file , Excluding Gravel XII. Percent Change in Constituents, Excluding Gravel XIII. Original and Present Constituents in the Profile, Excluding Gravel XIV. XV. XVI. XVII. Net Changes in the Feldspars of the Sand Fractions Composition of the Mariette Loam Profile, Inclu­ ding Gravel Original and Present Constituents in the Profile, Including Gravel Net Change With and Without Gravel 1 I. INTRODUCTION The study of the evolution of the present day charac­ teristics of soils from the original unweathered material has not developed as rapidly as studies in other branches of soil science. There are several reasons for this. Ob­ servation of soils in many places and under many different conditions required considerable time, but the acquired knowledge emphasized the need for an orderly arrangement or classification of soils based on their characteristics and manner of development. Soil survey workers, fully cog­ nizant of the practical viewpoint, were aware also of the necessity for soil genetic studies, but in most cases, had neither the time nor facilities to carry on the work. Until 19^-2, the study of soil genesis lacked two im­ portant factors necessary to all scientific studies, namely, a quantitative method of measuring soil development and its duration in time. In this year Marshall and Haseman^2 published the results of a quantitative study of soil development in which the change in mineral composition of the various soil layers with depth was assessed against a selected mineral known to be resistant to weathering. Cer­ tain assumptions were necessary and some of these might not be valid in the light of present knowledge. Nevertheless, this is the only quantitative method for studying soil 2 genesis that has appeared in the literature and its use­ fulness is now becoming apparent. The purpose of the present investigation was to ap­ ply the Marshall and Haseman technique to the study of a Gray Brown Podzolic - Podzol intergrade soil of Michigan in an attempt to determine its genesis and mode of forma­ tion. An tfinter grade” is the term applied to a soil showing characteristics of more than one major soil group. In this case, a profile typical of the true Pod­ zol soils has apparently developed in the A2 horizon of a soil belonging to the wray Brown Podzolic Group. Cline 12 has observed this condition in New York state and Gardner1^ has studied the occurrence of the "double profile" in Michigan. In the present study, two innovations in the Marshall and Haseman technique were introduced. Quartz was used as the reference resistant mineral instead of zircon as proposed by Marshall and Haseman. IGhe Geiger counter x-ray spectrometer was used to determine quartz and other soil minerals. 3 II. REVIEW OF LITERATURE The literature dealing with the study of soil for­ mation consists of contributions from many phases of soil science. Early workers were interested in the effects of single factors such as climate, vegetation, or parent material on soil formation and the work was largely des­ criptive. Later, this work was supplemented by contri­ butions from the study of soil organic matter, soil colloids, base exchange and the structure of the clay minerals. More recently, particularly in the last de­ cade, the trend has been toward a mineralogical approach. Much of this work has been qualitative and little atten­ tion has been given to the development of sound quantita­ tive methods. One of the earlier studies on the evolution of soils was that of Griffiths et al.1^, who observed the effects of vegetative changes on soil profile development in cen­ tral New England. Here, one hundred years of pasture and tillage had been followed by eighty years of white pine. The pine, in turn, was followed by forty years of hardwood forest. With increasing time under $)ine, the dark brown cultivated layer became thinner and organic matter accumu­ lated. At forty years some profiles showed a trace of leached A2 horizon and at eighty years, a recognizable 1+ true Podzol profile had developed. During the first ten years under hardwood occupation, most of the organic matter accumulated under pine disappeared, leaving a thin horizon. er in color. The B horizon deepened and became dark­ One of the very noticeable features was the change in the consistency of the B horizon under pine and again under hardwood. Under the young pine there is a wide variation of consistency from loose to tough, with a greater proportion loose to friable. With increasing age the soils become more compact and tenacious. Once the pines are removed, the soil under the young hardwoods again loosens up. The hardwoods have a decided effect on the soil, changing the structure found under pine to near­ ly one hundred percent crumby structure under the older hardwood groups. Hesselman2**- showed that the presence in a forest stand of species rich in basic buffers often determines the character of the upper part of the soil profile, as to whether it will become a mull or raw humus type. Larch litter is acid and rich in acid buffers, but is much rich­ er in basic buffers than either pine or spruce litter. The effect on the soil may be indirect, affecting the role of micro-organisms in their decomposition of humus. Lunt2^ also attempted to correlate soils in New Eng­ land with forest vegetation. He concludes that the type of forest vegetation is conditioned by the soil. He 5 pointed out that a good mull develops under a thrifty hardwood stand and occurs as a result of favorable soil conditions. Lundblad^ showed that parent material containing calcium carbonate was not necessary for the formation of Brown Forest soils except where they were formed under "acclimatic" conditions. He noted a different type of organic matter in the humus horizon of the Brown Forest than in the Podzol soil and assumed that a different type of weathering was responsible. Later2^ in confirmation of the Mattson theory of isoelectric weathering, he con­ sidered the Podzols to have developed through an extreme type of acid weathering, the typical Brown Forest soils through a mild acid weathering, with the "acclimatic" Brown Forest soil taking a middle course between the two. Q Chandler^ found that the colloidal material in the A horizon of the Podzol had a considerably higher silicasesquioxide ratio than the corresponding fraction of the Brown Podzolic soil which he studied, but the ratio in the B horizons of the two soils was the same. content of the colloidal material from the high. The organic horizon was The content of olivene, hypersthene and hornblende remained high in the A horizon of the Brown podzolic soil, but these minerals were severely weathered in the A hori­ zon of the Podzol. 6 Deb lif studied the movement of iron oxides in Podzol soils and showed that iron may move in any one of six dif­ ferent forms. He found that the amount of humus necessary to pejptize iron oxide sol varies considerably with the source of the h^amus and the concentration and pH of the iron oxide. The ratio of humus to ferric oxide was con­ stant for each kind of humus over a wide range of concen­ trations. From Deb!s work it is evident that any iron oxide sol formed by weathering in the upper horizons of Podzols should be fully peptized by the humus in soil so­ lution. Deb concluded that the precipitation of iron oxide sol in the B horizon was not due to exchangeable calcium alone or to colloidal flocculation of humus pro­ tected sols or to chemical precipitation of complex salts. He thought it would be necessary to postulate a micro­ biological mechanism for the precipitation of iron. k In a somewhat similar study, Bloomfield showed that an aqueous extract of pine needles brought ferric and al­ uminum oxides into solution and the iron was reduced to the ferrous state under neutral aerobic conditions. The ferrous iron, and possibly the aluminum were present in the form of organic complexes. The ferrous complex was not readily decomposed under alkaline conditions and, at pH 8.0, relatively large quantities of iron remained in solution. This seemed to be in agreement with the ideas k^ advanced by Stobbe. 7 Some observations made by Burges and Drover on Australian soils indicated that hair of the calcium car­ bonate in a profile was removed in fifty years. A dis­ tinct A horizon was developed in 300 years, at 1000 years a B horizon was noticeable and at 2000 years the soil had all the characteristics of an iron Podzol. Measurements were made on old beach lines whose age had been estab­ lished . Cline et al.**- 2 have reported on a series of profile studies on the soils of New York, based on the hypothesis that on calcareous parent materials in that state, soil development follows a sequence from Brown Forest, through Gray Brown Podzolic to Brown Podzolic and Podzol soils. The profile becomes increasingly acid in the upper part and the mull humus layer of the Brown Forest soil is gradually replaced by a strongly acid matted mor. The A2 horizon thickens and in the Gray Brown Podzolic stage, there is evidence of a double pro­ file developing. The structure of the B horizon changes. Microscopic studies revealed that clays were concentrated on the aggregates in the lower horizons and these had been translocated by water. Silicate clays played the dominant role in the mobile fraction of the Gray Brown Podzolic soils, while oxide clays appeared to be dominant in the Brown Podzolic soils. Physical and chemical studies showed that clay deposition followed the carbonate layer downward. 8 These workers pointed out that the thickness of the eluviated zone and the depth of clay accumulation in the so­ lum was related to the loss of "bases as a function of time and permeability of the profile. In a more recent study, Cline‘S showed that when the A 2 horizon of the Gray Brown Podzolic soil became strongly acid, yellowish iron films appeared on the primary par­ ticles in the upper part of the A horizon. This was in­ terpreted as the first sign of incipient Podzol develop­ ment. When the entire solum had become strongly acid, a weak Podzol profile appeared above the Gray Brown Podzolic B horizon. Illite clays dominated all horizons. In the southern part of the state, Gray Brown Podzolic soils occurred on both acid and calcareous materials, but showed no evidence of incipient Podzol development within a de­ grading Gray Brown Podzolic solum. It would appear from this that climatic factors were responsible, at least in part, for the formation of double profiles. A similar sequence of soil development was reported k% by Stobbe ' who investigated the morphology of the Gray Brown Podzolic and related soils of Eastern Canada. Stobbe believed that Gray Brown Podzolic soils were not formed by the podzolization process. He cites as evidence the high pH, high base saturation, accumulation of clay and lack of organic matter in the B horizon and the fact that podzolic degradation may take place in the upper part of the solum. Possibly the process differs in degree rather than kind. Stobbe pointed out that calcareous materials liberated iron and aluminum at a higher rate than non-calcareous materials, hence sesquioxides may be liberated before all the free calcium carbonate is removed. In a study of some Podzolic soils in the northern Ifo Great Lakes area, Nygard and his co-workers observed that Podzol characteristics were superimposed on other soils in the region, but advanced no theories as to how this had occurred. The characteristics of Podzolic soils in northeastern United States have been described by Lyford^. Some of these soils appear to be polygenetic, having a leached horizon and one of deposition in the place where the nor­ mal Ai and Ap horizons would have occurred. Such soils were observed to appear only on calcareous parent mater­ ials north of the Wisconsin terminal moraine, but on noncalcareous materials south of it. The occurrence of double profiles has also been re­ ported by Allen^. These profiles occur on till of both Mankato and Cary age, but development is more advanced on the Cary till. A further study of the morphology of double profiles was made by Gardner and Whiteside‘S . They believed that the upper part of the profiles had been developed from uni form materials - in other words, the profiles were genetic 10 The time required for the change from Gray Brown Podzolje was regarded as less than post-Mankato time since, as Allen pointed out, the profiles also developed in Mankato drift. Gardner and Whiteside believed that two processes were operating simultaneously, the formation of the upper horizons being accelerated by the climatic conditions. p U- Johnsgard^ suggested that the height of rise of ca­ pillary water above the water table may have considerable effect in determining the type of soil that will develop. He showed that a sandy Podzol had a marked depletion of hornblende, augite, actinolite and feldspars throughout the solum, whereas a Half-Bog soil did not show any marked change in these minerals. Cadyu studied soils developed from similar parent material under different vegetation. He concluded that the relative abundance of easily weath­ ered minerals in the Brown Podzolic A horizons indicates a lesser intensity of podzolization under hardwood than under spruce-hardwood. Hornblende and pyroxene are readi­ ly decomposed -under conditions of strong podzolization, while epidote, magnetite and garnet are little affected. In a search for a mineral sufficiently resistant to be useful as a weathering index, M i c kelson^ found that only zircon and tourmaline would meet the requirements and these were present in significant quantity only in the coarse silt fraction. He concluded from a calculation of the hornblende/garnet ratios that garnet fragments 11 decompose readily. Cady. This does not agree with the work of Mickelson also used the percentage composition of the mineral suite to compute his zircon/tourmaline ratios. It would have been more accurate to use the total amount or grams of constituent, since percentages change with weathering and loss of other minerals. In 19^2, Marshall and Haseman^2 described a quantita­ tive method for evaluating soil formation by the use of heavy mineral studies. Using zircon as the index mineral, they evaluated weathering losses from the solum by com­ parison of the zircon in the solum with that in the parent material. They used the size distribution of zircon as a test of whether the profile had developed from the under­ lying material. It was necessary to assume that the resis­ tant minerals had not undergone any decomposition and that they had not been translocated in the profile. One of the objections to the use of zircon is that it may occur rarely in some soils and in amounts difficult to measure. Other more common and abundant minerals might serve as well. Marshall and Haseman pointed out that the coarser soil fractions might be useful as indicators in soil genetic studies. Their results showed that profile development ex­ tends to a greater depth than is normally supposed. Further studies by Humbert and Marshall22 showed that the presence of ferrous ions in silicate structures causes a rapid break­ down when these are exposed to weathering agencies, due to oxidation of the iron. 12 Matelski and T u r k ^ reported studies on the heavy mineral fraction of some Michigan Podzols. They found that organic matter was an effective weathering agent in the B horizon and that heavy minerals in the B horizon suffered greater decomposition than in the A or C hori­ zons. They suggested that more accurate results are ob­ tained by subjecting the entire fine sand fraction to heavy mineral analysis rather than just a small portion. MickJ in a study of Michigan soil profiles gave an excellent review of previous mineralogical investigations by various workers. He found that hornblende was the most abundant heavy mineral in the drift. Mick expressed the hypothesis that, in certain profiles, the calcite of the lower horizons has changed to dolomite and supported this with magnesium analyses of the lower horizons. He dis­ cussed the evolution of a St. Clair profile and the changes taking place during development, but his method of calcu­ lating these changes is open to criticism, since he assumed that heavy mineral count percentages were weight percentages. This will affect, to some extent, the calculated gains or losses of constituents and thus create a false impression of the course of soil development. The mineralogical composition of a heath Podzol has been described by van der Marel^^, who pointed out that the potassium content of the feldspars decreased from the lower zones upward, especially through the A2 horizon. 13 He considered that this indicated a selective process in podzolic weathering as regards the kind of feldspar being decomposed. Silica gel increased from the surface down­ ward and aluminum hydroxide gels flocculated at a greater depth than the iron hydroxide gels. This work is somewhat similar to that of Graham-*-? who showed that the weathering rates of the plagioclase feldspars increased with increas­ ing calcium content. Graham considered albite as being extremely resistant to weathering. R o l f e ^ has studied the mineralogical characteristics of fourteen major soil profiles. He found that the micas showed a definite weathering sequence and could be used as a basis for a weathering criterion. He believed that pod­ zolization is essentially a process of iron oxide removal rather than one of mineral decomposition. He pointed out that dispersion of free iron oxides at a low pH is a func­ tion of the type of humus and therefore the production of a leached layer depends on the type of vegetative cover. Rolfe recognized two types of double profiles - one caused by a change in the weathering regime and the other result­ ing from two depositions of soil material in one profile. He concluded that there is an intimate relationship between the vegetation and the mineral content of the soil The choice of quartz as the standard mineral against which weathering losses were to be assessed led to a review of methods for determining this mineral. Microchemical l^f methods for the determination of quartz were tried and found to be unsatisfactory and mineralogical methods were necessarily tedious and not accurate enough for the pur­ pose. The recent application of the Geiger counter x-ray spectrometer to the determination of minerals seemed to offer a solution to the problem. Quartz has been determined by x-ray methods for a number of years, using the camera technique, but the use­ fulness of this method as a quantitative procedure has been limited by the many variables that exist in the preparation, mounting, exposure and interpretation of results. The Geiger counter x-ray spectrometer eliminates or minimizes many of these variables. The first method suitable for routine quantitative mineralogical analyses with x-rays was published by Clark and Reynolds 11 in 1936. These workers were among the first to develop the internal standard method. A pure crystal­ line powder known not to be present in the mixture was added to the unknown in a definite ratio and the diffrac­ tion pattern measured by a suitable apparatus - in this case a circular reflection camera. The ratio of the den­ sity of a line of the substance sought to that of a nearby line of the standard was determined photometrically. Following the publication of this paper, a number of workers applied the technique to mineral analysis. Heil­ man et al.20 reported on a quantitative procedure for 15 the estimation of montmorillonite and in 19*+V M a c E w a n ^ 1 reported further work along this line. White side**'7 applied the Clark and Reynolds procedure to the study of loess. This was the first application of the use of an internal standard with soil materials. Whiteside used ammonium chloride as an internal standard and introduced an innovation in the rotating sample method by filling the sample tubes only partially full in order to promote random orientation of the particles. Quartz, feldspar, calcite and dolomite were determined quantita­ tively. In 19^7 Jeffries2^ published an excellent description of the Geiger counter x-ray spectrometer and its use in determining essential soil minerals. He showed results of the qualitative analysis of the very fine sand, silt and clay fractions of several soils. 7 Carl pointed out the limitations of the camera tech­ nique and described quantitative methods using the Geiger counter x-ray spectrometer. He observed that the method was rapid, non-destructive, and practically independent of particle size, locked grains or minor surface coatings. Some later workers seem to disagree with this statement. A quantitative method for the analysis of heavy metal carbides with the x-ray spectrometer was described by R e d m o n d 1*^. He describes two methods for mounting the sample and emphasizes that the spectrometer must be standardized from day to day. 16 The use of the x-ray spectrometer for organic quan­ titative analysis has been described by Christ, Barnes and Williams^. They found widely variable results when particle size was reduced below 0.2 microns and pointed out that their method is valid only if the particle size distribution of the unknown is essentially the same as that of the standard used. They also found that crystal orientation could be overcome by mixing carbon black with the sample. During 19*+8, Alexander, Klug and Rummer2 ’ 26 published several papers dealing with investigations into the x-ray spectrometer operation and theory. They showed that the intensity of the diffracted rays were a function of the particle size, number of particles present and the proportion of particles favorably oriented. Their results seemed to indicate that good reproducibility was dependent on the particle dimensions being less than five microns. Later, Alexander and Klug^ developed the mathematical re­ lationships applicable to the quantitative analysis of powder mixtures with the x-ray spectrometer. They were able to show that experimental measurements of quartzite and fluorite mixtures fell on the theoretical intensityconcentration curves derived by mathematical analysis of the factors involved. Most investigators up to 19^8 had not used any stan*dard procedure for sample preparation and mounting. 17 McCreery37 introduced a method for preparing mounts espe­ cially for the x-ray spectrometer. Essentially, the ma­ terial is tamped gently into a hollow cell hacked by a glass plate. The surface is smoothed off and covered with another glass plate. The cell is then turned over and the original glass cover removed, exposing a smooth surface for irradiation. Among the first workers to apply the Geiger counter x-ray spectrometer to the quantitative mineralogical analy­ sis of soils were Phillippe and White*4-1. They used the McCreery technique, and sodium fluoride as an internal stan­ dard. These workers expressed the belief that the range in particle sizes introduced by grinding the samples may have some effect on the reproducibility. Phillippe and White give a good description of the spectrometer and re­ corder operation. Pollack*4-2 reported a study of the x-ray diffraction of sixteen common silica minerals and the effects of various factors on the reproducibility of results. Pollack used the McCreery technique and later made some changes in the method which decreased the standard error of the results. He investigated the effects of grinding and preparation of the sample and thought that the difficulty in obtaining reproducibility lay in the technique of preparing the sample and variations between different quartz varieties. 18 III. APPARATUS AND MATERIALS A, The Geiger-counter X-ray Spectrometer The instrument used in this investigation was a Norelco Type b2202 Geiger-counter x-ray spectrometer manufactured by the North American Phillips Company, Inc. of New York. It consists of a basic x-ray produc­ tion unit having an x-ray tube with a tungsten filament and cooper target. A nickel filter .0007 inches thick filters out all but the cooper K-alpha radiation. A wide range, high and low angle Geiger-counter goniometer is mounted on the unit and carries the colli­ mating slits and sample holder. tion have been described by The principles of opera­ J e f f r i e s ^ . The emergent beam was collimated by a slit having an angular aperture of one degree. This exposed about two- thirds of the focal area of the sample to the x-rays at the angle (26.60° 2&) at which the quartz was measured. 3.35 A. spacing of At larger angles, a smaller propor­ tion of the focal area is exposed to the beam. The dif­ fracted beam entering the Geiger-counter tube was defined by a slit having a width of .003 inches. A scatter slit with a four degree aperture was used between the receiving slit and the Geiger-counter tube to insure that only rays diffracted by the sample entered the tube. The sample 19 holder and Geiger-counter tube are motor driven and syn­ chronized so that an angle of 2© is always maintained in scanning. The goniometer was run at a scanning speed of one degree per minute and the x-ray tube was operated at 30 kilovolts and 15 mil Hamper es. A warming up period of thirty minutes was allowed before x-raying the samples. The intensity of the diffracted beam received by the Gei­ ger counter tube was electronically recorded by a Brown automatic recorder as peaks on a graph. The height of the peaks above the recorder background is proportional to the intensity of the diffracted beam. B. Soil Profile Investigated The soil used in this study was a profile of the Mar­ ie tte loam. The sampling site was located 200 yards east of the northwest corner of the northeast quarter of the northwest quarter of Section 33, Tl^-N, R13E, Sanilac Coun­ ty, Michigan. Here, the Marlette loam is developed on gently rolling topography outside the Port Huron moraine. The original vegetation consisted of maple and mixed de­ ciduous cover, but the site of the sample is now under sod. The parent material of the Marlette loam is a calcar­ eous loam till, thought to be of Cary age, and the profile shows the presence of carbonates at a depth of about 36 inches. The soil is well drained and comparatively free from large stones. The annual precipitation in this area averages 35 to bO inches. The upper part of the profile 20 shows well developed Podzol characteristics and the Mar­ lette loam is a good example of the Gray Brown PodzolicPodzol intergrade found in Michigan. A detailed descrip­ tion of the profile is given below. Profile Description H Horizon Depth in Inches Aip 0 — 2 .5 dark gray* (7 .5YR*+/0 ) silt loam; weak crumb structure; pH 7.5 A2p 2.5— *K 0 light grayish brown (7.5YB6/2) loam; very weak crumb structure; pH 5*5 BP lf.0— 9.0 strong yellowish brown (10YR5/6) loam; weak crumb structure; pH 5*7 A 2 GBP 9 .0 — 13.5 brown to dark orange yellow (10 YR 6 / 6 ) loam; weak fine granular structure; pH 6.0 bigpb 1 3 .5— 1 8 .0 brown to dark orange yellow (10 YR 6/ 6 ) loam; subangular blocky structure; pH 6.0 B21GBP 1 8 .0 — 2 7 .0 strong yellowish brown (10YR5/6) loam; medium blocky structure; clay coatings on particles; somewhat mot­ tled; pH increases with depth from 6 .5 at 23 inches to about 8.0 at 27 inches b 22GBP 27.0— 36.0 strong yellowish brown (10YR5/6) loam; medium blocky structure; pH 8.0 c 36.0— 7 2 .0 strong yellowish brown (10YB5/6) Description * ISCC - NBS color names are used herein 20 IV. EXPERIMENTAL PROCEDURE A. Preliminary Investigation The desire to use quartz as a reference mineral made it necessary to investigate the applicability of the x-ray spectrometer to its quantitative determination. workers2**’ Previous **2 have pointed out the significance of par- t i d e size in obtaining reproducibility. n Carl , however, observed that results were independent of particle size. A xreliminary investigation was carried out to de­ termine the significance of particle size on the diffrac­ tion intensity of quartz. A clear crystal of geode quartz, furnished by the Department of Geology, Michigan State College, was ground to pass a 325 mesh (M+ microns) sieve. This material was then fractionated by sedimentation into 2-10, 10-20, 20-50 and greater than 50 microns fractions. Samples of each fraction were then x-rayed and the result­ ing intensities recorded. Mounting and measuring the sample. The McCreery method^ as modified by Pollack1*'2 was used in mounting the samples. Aluminum slides or lozenges approximately bo millimeters square and 1 millimeter thick, having a rec­ tangular hole 10 by 20 millimeters were used to hold the sample. This provided a maximum focal area of 200 square millimeters. The opening was 21 covered on one side with a piece of glass , slightly larger than the opening, firmly ‘ bound to the surface with scotch tape. The sample was spread into this cell by tapping the material off a spatula until the cell was filled to ex­ cess. The material was then tamped into place by working the edge of the spatula over the surface. The surface was levelled off with a razor blade, more material spread on and the process repeated two or three times. Finally, the surface was levelled, covered with a glass plate taped to the slide, the slide turned over and the original glass plate carefully removed. This resulted in a smooth sur­ face for exposure to the x-rays. The slide was placed in the spectrometer and the intensity of the rays diffracted by the 3.35 A° spacing of quartz was recorded. The gonio­ meter was allowed to run two or three degrees (2©0 on either side of the peak intensity of quartz and the inten­ sity was measured with the angle 2© both increasing and decreasing. Thirty six measurements were made on each slide, 12 each on the center, left and right sections, by shifting the slide in the appropriate direction in the spectrometer. Thus it was possible to measure the variability within the slide resulting from preparation technique. In order to measure reproducibility, slides of each fraction were measured on different days. is given in Chapter V. A discussion of the results 22 B. Preparation of Soil Sample One hundred gram samples of each soil horizon -were treated with hydrogen peroxide to remove organic matter. After filtration and washing, the washed sediment was transferred to shaker "bottles and diluted with water. The suspension was made just alkaline to phenolphthalein and shaken overnight. The sands were separated from the silt and clay by washing m a 300 mesh sieve. The dried sands were weighed and fractionated by sieving into coarse and medium sand (2 - .25 millimeters), fine sand (.25 - .10 millimeters) and very fine sand (.10 - .05 millimeters). Any fine material passing the 300 mesh sieve was added to the silt and clay fraction. The sand fractions were then treated for removal of free silica and iron and aluminum oxides by the method of Marshall and Jeffries^. Heavy mineral separations were made on portions of the fine sand and very fine sand, using tetrabromoethane of specific gravity 2.90. A further separation of the light fraction of the very fine sand at a specific gravity of 2.70 was made by diluting the tetrabromoethane with ni­ trobenzene . For x-ray analyses, samples of the cleaned sand frac­ tions were ground in a steel mortar to pass a 300 mesh sieve. This material was used directly in the preparation of slides. 23 C. Analytical Determinations Mechanical analysis. Determination of the silt and clay content was carried out on the material washed through the 300 mesh sieve after separation of the sands. Bulk density determinations were made on core samples from each horizon. Organic matter and solution loss. Organic matter and solution loss were determined on separate samples of the air dry soil. Organic matter was determined by treatment with hydrogen peroxide. The residue from this determina­ tion was treated with 0.2 normal HC1. The loss in weight after washing and drying was regarded as solution loss. Mineralogical examination. A qualitative examination of the minerals present in the very fine sand fraction was made with the petrographic microscope. An examination of the coarser sand fractions was also made. X-ray spectrometer analysis. After preliminary inves­ tigation, it was decided to attempt to measure feldspars as well as quartz, since these minerals gave strong dif­ fraction intensities in a region conveniently near that of quartz. It was also decided to make the measurements with­ out the use of an internal standard, as used by previous workers, by comparing the peak heights of the unknown di­ rectly with those of known standards. This method saves considerable time in preparation of the samples and stan­ dards and in the calculation of the results. The 2b feasibility of such a procedure has been advocated by n /L Klug et al. when the unknown contains more than 60 per­ cent quartz. Consequently, standards xrere prepared of pure quartz, pure anorthite, pure albite and pure orthoclase. Check mixtures containing 80 percent quartz and 20 percent al­ bite and 70 percent quartz and 20 percent albite were also prepared* necessary. Calcium carbonate was used as the diluent where The pure quartz used is the standard and in the mixtures was the 2 - 1 0 micron fraction used in the preliminary investigation mentioned under A above. Slides were prepared in the manner described above for mounting and measuring the sample and the standards were x-rayed. The goniometer was run at a scanning speed of one degree per minute and was allox^ed to range from 26 degrees (2©0 to approximately 28.80 degrees (20-), which was sufficient to record the diffraction intensities of both the quartz and the feldspars. Four slides of each sample were prepared and two determinations were made on two sections of each slide, making a total of sixteen de­ terminations per sample. The soil samples prepared for analysis as described above x-jere mounted and x-rayed in the same manner as the standards. The ratio of the heights of the peaks from the unknowns to those of the pure minerals above the background was taken as a measure of the amount of mineral present. 25 The ratio of height of the peaks obtained from the soil samples to that obtained from the 100 percent standards was calculated as percent quartz or feldspar respectively. Attention was focussed largely on the quartz determina­ tions and the pure quartz standard was run each day at the beginning and end of other determinations in order to check the constancy of the apparatus and the repro­ ducibility of the results. 26 V. A. RESULTS AND DISCUSSION Results of Preliminary Studies The effects of the particle size of quartz on the in­ tensity of the diffracted x-rays are summarized in Tables I, II and III. Table I shows the mean peak heights ob­ tained from each size fraction run on different days, in order to check the variability of the apparatus and the reproducibility of the results. The peak heights in Table I are the means of 36 determinations made on each size fraction. TABLE I MEAN PEAK HEIGHTS OF SIZE FRACTIONS Second First Particle Day Day size (microns) 2 - 1 0 - 20 167.3 169.3 & 0 CM >50 166.9 1 10 16^.9 165.5 1 6 6 .5 135.0 197.1 The results indicate that particle sizes in the range 2 to 50 microns have about the same effect on the diffrac­ tion intensity of the x-rays. It should also be noted that the average of the peak heights for >50 microns obtained on different days is similar to those of the finer size 27 fractions. It is known, however, that very small particle sizes, below about 0.5 microns, do show variability in their effects on the diffraction intensity. In order to test the significance of the differences in peak heights between the different size fractions, Fisher's f,ttr value was calculated for (1) the difference between means of the same size fraction run on different days and (2) between the means of different size fractions run on the same day. These values are given in Tables II and III respectively. These values were calculated from the measurement of peak heights obtained with angle 2© both increasing and decreasing. A value of t = 2 or greater is required for significance at the 5 percent level. TABLE II SIGNIFICANCE BETWEEN MEAN PEAK HEIGHTS OF SAME SIZE FRACTION RUN ON DIFFERENT DAYS Particle Size (microns) 2-10 10 - 20 20 - 50 >5o "t" values between means of - . size fractions 10 - 20u 20 - 50u 2 - lOu Inc* Dec* Inc. Dec. Inc. Dec. .67 >50u Inc. Dec .12 1 .3 2 1.65 .38 1.13 13.3 11.' * Calculated from peak heights obtained with 20 increasing and decreasing respectively. 28 TABLE III SIGNIFICANCE BETWEEN MEAN PEAK HEIGHTS OF DIFFERENT SIZE FRACTIONS ON THE SAME DAY Particle Size utTI values between means of 2 - 10 u 10 - 20 u Inc.* Dec.* Inc. Dec. 2-10 .60 10 - 20 20 - 50 1.39 >50 u 20 - 50 u Inc. Dec. Inc. .16 .21 7-50 .26 .37 8.H-3 8.30 I ^.37 5.V6 ^Calculated from peak heights obtained with 20 increasing and decreasing respectively. The results indicate no significant difference in the effect of particle size on diffraction intensity be­ tween 2 and variation. ?0 microns. Above this there is considerable Calculation by the author showed that there also was no significant difference between values obtained with 20 increasing and with 20 decreasing, except above the 50 micron particle size. B. Determination of Quartz in Soil Fractions The results obtained in the preliminary studies seemed to indicate that the method would be applicable to soils provided that the material was within a given size range. 'The 2 - .25 millimeter, .25 - *10 millimeter and the .10 - .05 millimeter fractions were prepared as described in Chapter IV and x-rayed. The mean peak heights, measured 29 above the background, were calculated as percent of the mean peak height obtained from the pure quartz standard and the results considered as percent quartz in the frac­ tion. The results are presented in Table IV. TABLE IV PERCENT QUARTZ IN SOIL SAND FRACTIONS Soil horizon Very fine Sand Fine sand Coarse* sand Aip 91188 101.00 1 0 2 .6 0 A2p 91.08 99.86 102.7h Bp 85.10 97.01 92.18 a 2GBP 87.90 93.97 9 0 .8 8 b 1GBP 89 A 7 91.09 92.1+1 B21GBP 81.23 89.^ 9 0 .1 1 B22GBP 81.06 90.69 8 6 .1 6 c 83.06 91 .*+9 83.11 ♦Coarse and medium sand. The percentage quartz recorded for both the Alp and A 2 p horizons of the fine.and coarse sand fractions was over one hundred percent and the results in general would ap­ pear to be high. Several separate determinations on these two fractions consistently gave peak heights (in­ tensities) greater than those of the pure quartz standard. It was first thought that the difference in particle size 30 of the pure standard (2 - 10 microns) compared with that of the soil fraction (roughly 20 - ?0 microns) might he responsible. This would have been in contradiction to the results obtained in the preliminary studies. Conse­ quently, a sample of the 20 - 50 micron fraction of quartz used in the preliminary study was x-rayed. The peak heights obtained gave values similar to those of the 2 - 1 0 micron fraction. L.O Pollack in his study of quartz varieties had ob­ tained a lower value for geode quartz than for a sample of Ward1s quartz (from ¥ardfs Natural Science Establish­ ment, New York) which he had used as a standard. For­ tunately, a sample of the Ward!s quartz used by Pollack was available and this was ground to pass a 300 mesh sieve and prepared for x-ray in a manner similar to the soil fractions. The peak heights obtained from the Ward*s sample were considerably higher than those from the geode quartz, pre­ viously used as a standard in this investigation. A sample of geode quartz also used by Pollack was checked against the geode sample used in this study and similar peak heights were obtained. It is not known why the geode quartz gives lower values and this might be the subject of some fruitful investigation. It was believed that the Ward!s quartz more nearly represented the desired 100 percent quartz standard and 31 the values in Table IV were re-calculated on the basis of the mean peak heights obtained from the Wardfs quartz. The results are presented in Table V. TABLE V REVISED PERCENT QUARTZ IN SOIL SAND FRACTIONS Soil Horizon Very Fine Sand Fine Sand Coarse* Sand Alp 67.5+3 75+.13 75.23 A2p 66.85 73.29 75.5+1 BP 62.5+6 7 1 .2 0 6 7 .6 6 a 2GBP 6b. 52 68.97 6 6 .7 0 bigbp 65.67 6 6 .8 6 6 7 .8 2 B21GBP 59.62 65.61 66.15+ B22GBP 59A9 66.56 63.25+ c 6 0 .9 2 67.15 6 1 .0 0 *Coarse and medium sand. The percentage quartz is somewhat higher in the fine and coarse sand fractions than in the very fine sand, but decreases fairly regularly with depth in the profile in all fractions. ‘ Table VI presents the results in a different manner and represents the percent of the soil weight contri­ buted by the quartz from the respective fractions. 32 TABLE VT QUARTZ IN SOIL FRACTIONS AS PERCENT OF TOTAL SOIL Horizon Coarse sand Fine sand Very fine sand Total Aip 7.26 11.2 5 10.18 28.69 A2p 7.70 11.59 11.35 30.6V Bp 7.23 9-69 7.76 2V.68 A2GBP 6.33 10.11 9.36 25.80 b igbp 6.07 9.31 10.69 26.07 b 21BGP 6.12 8.62 7.21 21.95 b 22GBP 5.98 8.7V 8.75 23.V7 c 5.90 8.96 8.V9 23.35 Accompanying the determinations of quartz, the peak heights of the feldspars present in the soil fractions were recorded. Two principal peaks seemed to be evident and consistent throughout the analyses - one occurring at an angle of 27 .50 degrees (260 and the other at 28.10 de­ grees (26). These correspond approximately to lattice spacings of 3*23 A. and 3.16 A. respectively. The peaks were taken to represent respectively the orthoclase and the plagioclase feldspars, but the identification of any particular feldspar was not possible, since the reflections from the various feldspars tend to overlap in this range. The respective peak heights were measured and calcu­ lated as percent feldspar by comparison respectively with 33 the peak heights obtained from pure orthoclase and pure albite. The results presented in Table VII may be re­ garded as comparative only since, in many cases, the amounts present were so small as to make accurate mea­ surements questionable. It is possible also that other feldspars besides orthoclase, microcline or albite with nearly similar spacing may have been present and contri­ buted to the peak height. However, some idea of the re­ lative amount and distribution of the feldspars is brought out in Table VII. TABLE VII PERCENT FELDSPARS IN SAND FRACTIONS Orthoclase Feldspars Plagioclase feldspars Soil Very Fine Coarse Very Fine Coarse Horizon fine sand Sand Fine sand sand _________ sand___ ______________ Sand___________________ Al p 7.63 8 .5 6 2 .2 3 5 .8 0 5.50 1 .6 8 A2 p 8 . 6*+ ^ .9 6 3.^ 5 **.20 1 .6 0 2 .9 0 BP 7.2 7 ^-.96 >+.16 5.26 1 .6 8 3 .8 9 A2GBP 8 .0 5 5-17 ^ .0 3 6.33 2 .9 1 ^ .9 6 b 1GBP 8.h2 3 .8 1 if. 60 6 .W 1 .7 5 5 .2 6 B21GBP 6.3 3 1+.88 2 M 5-31* 3 .8 9 5.19 B22GBP 6.12 ^ .3 7 2.58 5.79 2 .5 2 5.95 c 5.96 5.25 2 .88 7 .2 5 2 .9 0 V .6 5 3^ The figures in Table VII reveal a tendency for the feld­ spars to be more abundant in the finer fractions of the soil. The distribution throughout the profile is vari­ able. The orthoclase feldspars tend to decrease with depth in all fractions , but the plagioclase feldspars show a somewhat irregular tendency to increase with depth in the profile. This probably reflects the greater ease of weathering of the plagioclases. C. Results of Physical and Chemical Analysis The results of physical and chemical determinations on the Marlette loam are presented in Table VIII. The mechanical analysis indicates that the profile has de­ veloped from material similar to that now underlying the solum and appearing as the C horizon. The high organic matter content in the Bp horizon indicates movement of organic material. The increase in bulk density with depth indicates that either considerable material has been lost from the original solum or there has been an increase in volume of the original material. both of these processes occur. As will be shown later, The silt and clay content varies irregularly with depth in the profile. A high silt content in the A horizons is accompanied by a hjgh total sand content which modifies the texture. A high clay con­ tent occurs in the Bgi horizon and this may be the result of soil development processes. It might be pointed out I 3? i —I0 •H Jh. -P a o © © -p >>CM 4 O 0 0 • -P 0 >**0 I © O hfloiin ,0 © HI «H © > CO • H PI no O i —•1 ON UN i 5 CM CO On I —I * NO H 00 H • UN H C M 00 ■ lr \ i— 1 UN co C M • OH vO C M co • a pj OF THE MARLETTE U PI O COMPOSITION Un P i- • CM i— 1 H H • NO H CO ph NO « nQ H UN ON ON co co • ON CN- 1 — 1 H CM no • O P i- ON H • CM pi- t> i— l • H o• ph• pJ- no CM P i- H UN • ON CM P i- NO H ON O • CM i— 1 C M ON • no i— 1 ph H • no H H C n. i— 1 • • C M C M ph ph H no ON • no H no H • no H pi­ rn • no i— 1 • ph I i—l •H <© a p 0 ©OP p p 0 O H © 0 I0 o a p 0 0 •H C M*H •H H C M NO • no H NO NO • H I 0 0 0 *H 0 H ©H 0 *H 0 aP •p P © o 0 0 0 lT \.p p -jpi 0 p a •H 0 *H tt d H HP ©P P© *H <~j PQ p w) a © o O • H C M O • H ph o• 1 — 1 H UN • H NO NO ♦ H UN NO • H UN o• 1— 1 oCO • H 0 0 0 O H P O P o *rl P O M P* Pn H P C M P PQ PH PQ cO C M < Ph pq cO I— 1 PQ PQ cO i— 1 C M PQ Ph PQ cO C M C M PQ «H P O O CO * 36 here that the results in Table VIII, except bulk density, are based on the weight of oven dry soil from which the gravel greater than 2 millimeters has been removed. density determinations, however, include the gravel. Bulk Or­ ganic matter plus sand, silt and clay total one hundred percent. The effect of the gravel on the calculation of changes taking place during soil development will be discussed later. D. Mineralogieal Studies A qualitative examination of the heavy minerals separated from the very fine and fine sand fractions was made to determine whether or not any particular mineral was more abundant than others. Table IX gives the per­ centage of heavy minerals found in the fractions, the best yields being obtained from the very fine sand. 37 TABLE IX PERCENT HEAVY MINERALS IN SAND FRACTIONS Horizon Very fine sand Fine Sand ■^lp 3.78 0.?0 A2p 1 .1 6 o.Vo BP 3.90 0 .6 0 A 2GBP 2 .3 2 o.?o bigbp 2.68 0 .5 0 b 21GBP 2.3^ 0 .8 0 B22GBP 2.00 0.70 c 2.22 0.90 As is the case in many Michigan soils, the heavy mineral suite was dominated by hornblende. This material varied widely in its degree of weathering, from the dark green slightly altered mineral to grains partially altered to chlorite. The hornblende was less abundant in the Ap horizons than deeper in the profile, but there appeared to be little difference in its abundance in the various horizons below the A 2 p layer. The other accessory minerals observed were augite, hypersthene, diopside, epidote , tourmaline, rutile, leucoxene, garnet and zircon. Opaque minerals included ilmenite and magnetite• An examination of the whole coarse sand fraction from 38 the C horizon gave some indication of the origin of the parent material. The fraction contained fragments of mica schist, fossiliferous limestone, quartzite, syenite and some sandstone. nant minerals. Quartz and feldspars were the domi­ The variability of the quartz was par­ ticularly noticeable. It occurred as sharp, angular transparent to translucent grains and in subangular, frosted forms. Both rose quartz and the smoky variety were present and a small percentage of the particles were spherical in shape as though wind blow. In the separated finer fractions and the unseparated coarser fractions, the micas were conspicuously absent. A few fragments of muscovite and biotite were observed, but they were widely scattered throughout the fractions. A count of the zircon in the heavy mineral fraction of the very fine sand showed that it ranged from 3.97 to 7.25 percent, these extreme values occurring in the B 21 and B22 horizons respectively. The zircon content of the other horizons was quite uniform, varying from 5 A 0 percent of the heavy mineral suite. h.hO to 39 VI. APPLICATION OF ANALYTICAL DATA TO THE STUDY OF SOIL DEVELOPMENT It is intended in this section to apply the results obtained from x-ray and analytical determinations to a study of the formation and movement of materials in the profile of the Mariette loam. As in the Marshall and Haseman technique, a resistant mineral - in this case, quartz - was used as a standard against •which net gains or losses in the profile were assessed. The method in­ volves certain basic assumptions, namely, (1) that the profile has developed from material simi­ lar to that now regarded as the C horizon and (2) that the quartz originally present has not been weathered, formed or translocated in the profile. The results of the mechanical analysis indicate that the present profile is genetic. The second assumption is not strictly true since all minerals eventually undergo wea­ thering. Even zircon has been shown to weather under cerR tain conditions . However, in relation to other minerals in the profile, quartz may be regarded as being very resis­ tant under the environmental conditions found in Michigan and the sand sizes are not regarded as being mobile -under these conditions. In this study the total percent quartz found in the sand fractions of each horizon (Table VI) is used as a basis of calculating the gains or losses in the profile. The method of calculation is described below. ho A. Method of Calculating Data The changes in the profile due to soil development were calculated as grams of constituent gained or lost from a column one square centimeter in cross section to the depth of the solum. The steps involve the calcula­ tion of (1) a volume change factor, (2) the original weight in grams of each constituent, (3) the present weight of each constituent and 0+) the difference between (2) and (3) to give the net gain or loss. From the percentage quartz in each horizon the amount of quartz per 100 cubic centimeters was calculated by mul­ tiplying the percentage quartz by the bulk density of the horizon. Using the C horizon as a standard, the number of cubic centimeters of parent material required to produce 1 cubic centimeter of the present horizon was obtained by dividing the grams quartz per 100 cubic centimeters of each horizon by this value for the C horizon* This gives a !volume change1 factor for each horizon. The original weight of each horizon was found by mul­ tiplying the volume of each horizon (= depth in centime­ ters) by the volume change factor times the bulk density of the C horizon or parent material. This weight multi- * plied by the percentage of each constituent in the C hori­ zon (Table VIII) gave the original weight of each consti­ tuent. The present weights were similarly calculated from hi the present weight and percentages of constituents in each horizon. B. Results and Discussion The volume change factors calculated for the Mar­ ie tte loam by the method described above are presented in Table X, and the calculated net changes in weight of constituents for each horizon are shown in Table XI. The percentage net change is given in Table XII. TABLE X VOLUME CHANGE. FACTORS FOR THE MARLETTE LOAM Horizon Percent Quartz in Soil Grams of Quartz per 100 Cubic Centi­ meters Volume Change Factor Aip 28.69 28.69 .66 A2p 30.6^ 31.25 .72 BP 2*+.68 25.67 .59 A2GBP 25.80 38.96 .89 b1GBP 26.07 lK3.28 .99 b 21GBP 21.95 36.22 .83 b22GBP 23.^7 Vl.07 .9*+ c 23.35 1+3.66 1.00 The grams of quartz per 100 cubic centimeters show consi­ derable variation throughout the solum due to changes in volume taking place during soil development. The least k-2 change appears to be in the B i q b P horizon. The data in Table XI show the changes in weights of the horizons due to soil formation processes. Organic matter has increased in all horizons of the solum, but particularly in the A^p, Bp and B^iq b p horizons. Since added organic matter comes principally from the surface, this indicates that translocation and deposition of or­ ganic colloidal material must have taken place in the profile. About 8 ? percent of the soluble material has been lost from the solum, the percentage loss being highest in the A 2p and B-^-gp horizons. The sand fractions all show small losses in weight from the solum, but the actual percentage loss is, in general, below 5 percent. Such changes are negligible if it is considered that particle distribution through the original material was not strict­ ly uniform. Thus small changes in the percentage of sand in the parent material might occur with change in depth cr position. There is a distinct loss of silt from each horizon. Some of the finer silt has undoubtedly weathered to clay minerals, but there seems to be definite evidence of translocation in the profile• A considerable loss of clay has taken place from the surface, nearly 60 percent of the original clay plus what­ ever may have been formed having been removed from the ^3 0 0 bO pift • -P cd 0)xl is;O I o NO • o• P i CO no ft + i 1 CM ph • ON E r\ ETN ft 1 NO ft o i—1 ft + • I ft 30 ft 1 -P ft n3 3 cd CO 0 ft ft is ; M 0 fn cd o o Pi -P 0 0 Xl 0 bo 0 tH Pi 0 PL, ^ ft NO • ft Jr E f\ pift no CM CO L f\ ft no no On no ON ft no X) no ph ft ft ft COft ft ft H EfN ft NO no ft ft ON INft ft no CM. ft CM no ft no NO no CM CM ft no I ft no ft ph 1 CO ph • no CM CM CO ON * ft ft ft ft cd Pi -P *H X l lT\ ft b 0 bO •H *H $-t 0 ON • no ft ft Q X 0 0 bo m -P cd 0 Xl n ft O PI Ph S 0 0 o ft s 2 M I"— » X M a CQ EH pq EH |SJ pa 6 o *rl ON no ph Cd O O C\J no o Er\ • pi*ft CM 1 O -P Pi -P 0 0 XI 0 bQ 0 *H p, Pt 0 tm 2 p i- 1 CO ft EfN PH ^ i —1 O CO I—I cd Pi -P 0 •H X l bO bO •H f t Pt 0 NO ON 1 —•i O• 1—1 no NO CM oft • EfN NO -d L T*N no ft ph ft E>pt* * ft ft -1“ + CO ON • ft 4 + EfN ft • CM • CM PT• no po CO 1 — 1 CD EH 0 m l-rs> 0 W) o -p PS 0 d p] o is; X l be Eh C M ph NO + * + + On ft rH CM t>- NO ft oft EfN • • ft ft CM o Al 0 -p -p cd Ah o •H ft bC £5 s t—t 1 o• -P ! —I is; pa c r-aJ 1 — 1 1 NO CO • ft 1 O- ft -p 3 -p 0 0 xl 0 bd 0 -H fn Pi 0 tK Ph 133 pi* VO no m (M CO A no !—1 cd w abOsbO M f t ft s O O Pj b( CNO UN J- CO O H rH no CM EfN no O ph CM p i" Pi 0 *3 £ o ft pq ft N •H U O W ft ft ft CM <*} a 3 o CO • Cd • UN 4 UN ON • CO UN • CVJ H o CM CM • CO i— 1 * t— 1 + O H + 4 o • rH i—! UN CO • CO UN • CM O i— 1 NO « CVJ CM ON CO • rH 4 O i—! • co CM CO o • iP v rH 4 o cO • CM On I—I cd w sd 0 i sh •H S O *H 0 HO J3 *H -P -P •Hi—IrQ p 0 H o p0g o> oo TABLE XI (continued) 0 to •p 0 ^ o SH ^0 Un i— 1 • oh ph co • C\J Opi" • ON t—1 i—i 1 C M • 1 cm oo o. UN CO • CVJ t> - IN - CO • ON • CO rH 1— 1 CM 00 CO • CM CO CM • CM l>- UN • i— 1 00 • 1 , rH Cn . • 1-- 1 1 t 4 i— 1 E>• CM CM • rH O- i —•1 1 -p s 0d-p dd ^d i—i cd -P O EH c o hO d 0 -H pH SH 0 HO O ro CNJ • o• vo ph PH p: NO CVJ • CO NO UN • NO • H rH O- O- o CM ON CM • CO CM Ph • O Ph l>- o NO • L T\ i o CO ♦ CO co rH rH Cd dsi uo ho d •H *H P SH 0 HO h Cn . O• o- — i I CO • lr \ C5 0 W HO H -p sd B 0 Cd pH PH HO co • E>UN • oo• rH ph • CO H CO CM • i—1 NO • ph CO i—! 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A^p horizons. There is a small percentage loss of clay from the Bp horizon, hut the accumulation of clay in the Bg^-gp horizon is very marked. This is the only horizon in the solum showing a distinct gain in weight. The increase in clay may he due, in part, to formation in place, hut the losses in the solum ahove this horizon is evidence of translocation of consider­ able fine material. Further evidence of translocation of the clay may he found in examination of the structu­ ral units of the lower horizons. Here, fine clay may he detected on the walls of root channels and on cleavage faces. There is a net loss in weight of the solum of 5*6 grams and a total volume increase of 15 cubic centimeters or 19.5 percent. Large volume changes occur in the A^_p? A2p and Bp horizons where loosening of the soil hy plant roots and the addition of organic matter is taking place. A volume change of 20.5 percent occurs in the hori­ zon which may he attributed largely to microplastic move­ ment of the clay. B 1 GBP The very small volume change in the horizon is worthy of hote. It would appear that ad­ ditions and losses from this horizon are such as to offset any marked change in volume. It was thought that a mechanical analysis of the sand, silt and clay on an organic matter-solution loss free basis might give a clearer picture of the changes in b8 I Ph -P 00 fcuDg UN Cd • NO rH • ON Cd • O Cd • c|j Ph 1 1 1 i 0 bfl PQ o U~n Cd • 1 fti—1 • ft3 • ft i UN ft • rH \ 0 1 0 <—I *§ i—I O 0 d ft d -P 0 3 cd 0 ^ 0 co m bo cd 0 *H u 0) Ph 0 bC H PM 3: •H Ph rH cd H a -p 0 •rl ^ a bO tuO cd > •H *H Ph SQ 0 buq •rH CO ON * 00 NO • Un On • rH co • Cd i—1 ft• co co NO • Un co On • Un rH f t • rH CM S3 o ft 0 IQ 0 0 rO OJ • 1—1 ft* oo * f t" Cd • OJ cO ON • cd NO NO • ro SH ftUN • Un cm ft“ NO o NO co • CM cd ft w 0 0 , ft I—i d 0 m too • oo o • no O • cd Cd • 1 I t t co H Sh -P cd Ph 0 33 bti S M !— I M x pq di PQ Eh Cd * ftrH • CM O • i H* ft CO cd NO • 0 0 Ph 1 O 0 O S3 -P Ph f t 0 no 0 jn dSi f fl too 0 *H Ph CO Ph 0 0 js tf ON • U \ \D • rH ON • rH cd ro • cd NO OO • CM NO ON • ft* rH NO • lr \ UN CM • ON rH CO rH • ro cd co • ft- ON UN • UN t> OO * ON rH t«3 Ph S3 •H 0 pH d -P 0 •H o CO I —1 *H O CO w *H^3 ^ bO tuO Co •H *H Ph Ph 0 O ts 0 0; toO0 S3 0 CO o • 1— o • ft o un * cd d •H 0 0 0 rH O • o rH • UN o * ON 1—1 • 1 1 ft 1 ON o -P 0 0 ^ PWhI ft" ON • rH CO -3 * * ftCO » NO rH • I 1 1 i—1 rO • rH i •0 0 s Ph • O0 •ft S3 S3 *P 0 i 0 CO m bo 0 0 -H Ph 03 a 0 0 Ph 0 O O Ph 0 tiq pH 3i —I 0 d -p « *H ft £3 OJ NO * CO oO OO CO CO • Jr • rH 1— CN• CO '"C bO bO 0 •rH *H Ph 00 Cd • i—1 • 1—I OnO • rH Cd NO • I-- 1 o rH • Cd Un co * Cd ON H • ro 3U "N • fO O • fO Ph 0 bq O ft 33 rO rH • ro i—1 0 0 ftr Q 0 0 0 0 0 Ph > > ft t—I 0 Ph d & 0 ft ft <—i0 0 a d 8 CsJ «H Ph O CM CO • I—1 rH ft *rH Ph 0 ft PQ ft rH <£J ft ft Cd ft PQ Cd ft PQ ft i—1 PQ ft PQ ft rH cm PQ ft PQ ft CM CM PQ •H O tuO*H •H 0 P H O CO SH O 0 bO b-9 i 0 co Sh 0 f t Cd Sh 0 ft U ft o i TABLE XIII (continued) ft CJ f t CO 0 ft a CO CiO CO 0 -H Sh •n. SH 0 W £•« f t i—1 I 6 cd K H ft *H f t W) &D •H *H U ,0 O ft co g cd h w 0 txo Sh cd CO g Cd H taJC ft 0 ft ON ft* rH i o ro • nQ OO• CS- ft rH ft ' CO # • 1 1 ft O • f t H ro • lr \ tN. O• ir \ • 1 i M3 ft * ro H O- O • ft i—1 NO f t • H (ft CO oo • rH ft • 1 1 NO (ft • NO H UN (ft • o ft (ft ft• OO H oo 1—I • rO ft NO NO • NO ft• 1 1 I oo ft oH •’ + 1 • ft ON ft (ft oo NO o • UN OO ft* oo • ft + ft ft ■ O ft ON UN * o ft o NO • Un 1 o co • OO OO i—1 rH rei 0 ft cd m txo H 0 *H O Sh 0 ft ft 0 cn § ai PS 0 a 0 & cd }Q W rH nQ • vO oo • ON ON • i—1 (ft UN OO UN NO ft- i—1 ON • ft• ft OO co EN- UN • • • CO ft S 0 •H O cn h •H w g cd Ph txC ITS ro • tH rO ON • UN ft• ft ro ft • OO f t o • ft ft H • NO OO • O- ON H • UN ft O CO £ *H CO CO Cd 0 CO tS3 g Sh cd f t cd H, 0 ft w ft O ft Sh f t CO 0 ft £ C O CxO 0 ft iH 0 *H Ph •H Sh 0 M CO f t f t rH cd Sh f t •H f t £0 £0 •H *H Fh 0 SO ft o N •H Sh O ixj CO g Cd Fh tuO O- nO • I 00 ft* • 1 oNO • iH NO • o o • oo Un nO Un • Oftm • 1—1 1 1 1 1 1 ft i nO nQ ft co nO OO o 00 ft ON H Un oo OO ft f t ft rH Un [ft 00 ft i—1 NO rH oU \ ro oo • ro O- ro O • NO 1—1 ON • (ft ft ON • ON ft O ON oo • ' On CO • Oi—I NO ■ • OJ • ft • • • • • Un i— 1 • m rH i —I o pH rQ 0 * Sm SH *H 0 10 f t cd Fh <—1 PQ rH pq ft pq 0 Cd f t o •Sri ft? pq o aj ft PQ g P (—1 o co t 0 CO tuO *H Jh U O O 5c the insoluble constituents in the mineral fraction of the s°tl* Such an analysis had been performed on this soil pre­ viously by students in Soil Science. The volume change fac­ tors obtained in the present investigation were used to cal­ culate the net changes from these data and the results are presented in Table XIII. It would appear that considerable soluble material was contained in the sand fractions. A net increase in clay in the solum indicates that some clay formation has taken place. The movement of materials is brought out more sharp­ ly in this table. Some idea of the changes taking place in the feldspars may be gathered from the data in Table XIV. These data are comparative only as explained earlier and indicate a trend. TABLE XIV NET CHANGES IN FELDSPARS OF THE SAND FRACTIONS Plagioclase Feldspars Net change Change percent grams .0 2 8 +2 0 .1 - .025 -18.9 A2p + .009 + 9 .6 - .0 5 2 -53.5 Bp + ..OlV + 5.5 - 55 .*+ A2GBP + .053 +1 6 .1 - .0 3 8 -1 1 .2 Bi GBP 4 .0 6 1 +1 ^ .6 - .07 ^ - 1 6 .8 b 21GBP Urn .025 - 3.9 - .0 3 6 - 5.6 B22GBP - .Obi - 5*6 .O1^ - 5.8 Solum * .099 + 3.8 Lj 0 + 1 Aip • 0 00 'O Orthoclase Feldspars Net Change Change grams percent 1 Horizon _-13.3 51 The total feldspars show a net loss from the solum which is more evident in the plagioclase than in the orthoclase feldspars. The percentage gain or loss is small except in the A 2p and Bp horizons where the plagioclase feldspars have lost about 55 percent of their original weight. In general, the feldspars in the sand fractions do not appear to contribute very much to the net changes in the horizons. Since the bulk density exterminations include the gravel in the soil, it was thought that a comparison of the net changes, excluding gravel, should be made with the changes when gravel was included in the calculations. The composition of the soil when gravel is included is given in Table XV. The effect is to lower the percentage of constituents given in Table VIII, particularly in the A2p, Bp and B22GBP horizons where the percentages of gravel are high. The net changes including gravel are shown in Table XVI and a comparison of the net changes with and without gravel is presented in Table XVII. The most significant changes, when gravel is included, are the apparent in­ crease in the weight of gravel in the solum, especially in the B22GBP horizon, and the reduction in total weight loss from the solum. As explained above, this may be due to irregular distribution of gravel in the original ma­ terial. A high gravel content in some of the present 52 horizons would thus appear as a large gain in weight and should not be interpreted as translocation or accumula­ tion in the profile. This condition of heterogeneity is less likely to occur as the fractions become smaller in size. In the ^22QBP horizon the effect of gravel is to double the change in volume. C. Suggestions for Further Study The results obtained have revealed possible sources of error in this type of study and suggest additional lines of investigation that would be helpful in the in­ terpretation of the data. The following suggestions are proposed as a guide for future work of this nature. 1. The whole soil, including gravel, should be stu­ died. In soils containing considerable gravel, this may be an important factor in computing net gain or loss from the solum. The percentage of constituents should be calculated on the weight of the total oven dry soil. 2 . A total chemical analysis of the soil would be useful in tracing the movement of the various chemical constituents. 3. An accurate quantitative determination of the feld­ spars would give information on the formation and movement of the clay. The x-ray technique devel­ oped in this study could be applied to the deter­ mination of the feldspars as well as to quartz. *f. The C horizon should be sampled at sufficient depth so that the true parent material will be obtained. This may only be revealed by subsequent analyses. 53 5. In the study of an intergrade it would he helpful if a profile of the zonal soils to ’which it is related could be studied. In the present case it would have been interesting to compare the inter­ grade with the profiles of a true Podzol and Gray Brown Fodzolic soil. 6 . The results obtained by this method might be com­ pared with those obtained when zircon, determined chemically or mineralogically, ■was used as the re­ sistant reference mineral. 7. The possibility of using the quartz/feldspar ratio to determine the volume change factors of­ fers another method of approach. 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CD © X to XI © -P > O cd Sh ha H Ph © 3 O Pi ctS rP a CM 4 oo NO • OO X 4* IN ON • oO CM Un CO • oo 4 On oo • X 4 CO OO X + UN CO • oo + X IN • X 1 CO OO • CM I OO CM • CM 4- EN X • + ON NO + rH I On NO • X 1 OO CM • CM + IN O oo • CM 1 X • CM X + + -¥ o +5 Cl) p r H o © X I> I—I -p *H ^3 O *H cd X Ph P I © X -P ft! © Ph © -p © oooa rH © 1 W O X Ph ■P cd X X > *H -P © ft! -P X Sh P © © © ■CS O O g • + in • CM + o • UN 1—1 + OO • IN i—1 4 3 •H -P £ O O 'X H 1 —I X M S P rH O © to X <4-3 cd cd H t> S X• SH Ph H I cd ftO cd o i —1 © to IH > cd Sh cd a © Ph bo oo CM * i—1 1 • 1 * 1 O NO • UN 1 oo X X• X• CM + 1 PQ 15 -P g O H© © X > S X cd cd (N • ITN • oo CM • X NO • nO r 1 1 1 1 i—i X * NO * nO cd cd • X UN • ON in |3 Cd ho i 1 1 1 I \D tN • NO UN • oo CO • X •H SH H H © x o co w) i—i © to X K” S x X Ph Ph o • EN • NO CM • CM 4 ON • EN O • 1 1 X oO X X o + 4- • • X jd rH O©© X i> s X © © x P Ph ^3 O W X X X CQ X X X ^ X © © X• X X• X S 1 1 1 1 1 CM oO EN • UN ON • 1 1 Pi Ph PQ O) CM r* § nO cd • IN x• U Ph Cd hO 1 I © On • X oo oo • X 1 ft! o N •H Ph O w Pi rH <4 Pi CM <4 P Q Ph PQ CO X pq co X• IN co • l ON CO • i 1 Ph PQ Pi pq cd X CM PQ cd X co • UN 1 o Un • UN 1 3 P CM X CM o to PQ 60 VII. CONCLUSIONS In an investigation of this nature, conclusions can only be based on the net changes that take place in the profile. The processes by which such changes come about and the time required for their completion is not known, although often certain inferences and deductions can be made. An examination of the data obtained from the Mariette loam profile reveals a rather marked change in the profile at the BlGBp horizon. 'There may be two reasons for this. More recent material may have been deposited over older material of different composition or, there are two pro­ cesses occurring simultaneously in the same profile. The mechanical analyses show that the profile may be regarded as genetic and evidence of two processes occur­ ring in the profile is found in the following facts.,, The gains in organic matter through the solum indicate a movement of organic material from the A2p to the Bp hori­ zon. A trend is shown in the loss of soluble material, the percentage loss decreasing from the A2p to the A 2qbp an(^ increasing again in the BlGBp horizon. The net loss of silt from the B^qbp is the highest in the solum, although per centage—wise it is less than In the App and A2P hori­ zons. There is little difference in the percentage loss 61 of clay from the A2GBP ancl Bp^gp horizons, but the in­ crease in clay in the B22GBP horizon indicates that move­ ment into that horizon is taking place, The small volume change of the B^qbp horizon is another factor that dis­ tinguishes it from other horizons. This may be due to net losses of clay to this horizon, only small additions of organic matter and little disturbing influence of plant roots. It appears that, in addition to eluviation of the surface horizons and deposition in the Bp horizon, a se­ cond eluviation process is taking place belox/ the Bp hori­ zon which reaches Its maximum in the B1GBp horizon. This *i / would support the contention of Gardner and Whiteside that simultaneous processes Involving the movement of dif­ ferent constituents and their deposition in different parts of the solum occur in soils with double profiles. There is a possibility that the C horizon, as sampled, does not represent the true unweathered parent material, since small losses are recorded for the B22GBP horizon. It would require further sampling and investigation to check this point, but it is believed that the sample ob­ tained closely approaches the true parent material. 62 BIBLIOGRAPHY 1. Alexander5 Leroy and Harold P. King. Basic aspects of x-ray absorption in quantitative diffraction analysis of powder mixtures. Anal. Chem. 20: 886-889, 1 / 1U • 2. Alexander, L. , H. P. Klug and Elizabeth Kummer. Statistical Factors affecting the intensity of x-rays diffracted by crystalline powders. Jour. Applied Physics 19: 7^2-753? 19^8 . 3* Allen, Bonnie L. An investigation of the character­ istics of some soils on glacial moraines of Cary and Mankato age in Sanilac county, Michigan. Unpub­ lished Master of Science Thesis, Michigan State College, 1951. V. Bloomfield, C. A study of podzolization. Sci. IV., No. 1, 5 - 23, 1953. 5. J. Soil Burges, A. and D. P. Drover. The rate of Podzol development in the sands of the Woy Woy district, New South Wales. Australian Journal Botany 1: 1 : 83-9^? 1953. 6. Cady, John G. Soil analyses significant in forest soils investigations and determinations: III. Some mineralogical characteristics of Podzol and Brown Podzolic forest soil profiles. Soil Sci. Soc. Amer. Proc. (1939) 5: 352, (19^-0). 7. Carl, H. F. Quantitative mineral analysis with a recording x-ray diffraction spectrometer. Amer. Mineralogist 32: 508-517? 19^-7. 8. Carroll, Dorothy. ViTeatherability of zircon. Sedimentary Petrology 23: 106-116, 1953- 9. Chandler, R. F. , Jr. The relation of soil charac­ ter to forest growth in the Adirondack region. N. Y. (Cornell) Agr. Expt. Sta. Annual Report 5^: 93-9^, 19^1. Jour. 10. Christ, C. L. , R. B. Barnes and E. F. Williams. Organic quantitative analysis using the Geiger counter x-ray spectrometer. Anal. Chem. 20: 739-795? 19^8 . 63 11. Clark, ^G. L. and D. H. Reynolds. Quantitative analysis of mine dusts: An x-ray diffraction method. Ind. and Eng. Chem. Anal. Ed. 8 : 36-^0, 1936. 12 . Cline, M. G. Profile studies of normal soils of New York. I. Soil profile sequences involving Brown Forest, Gray Brown Podzolic and Brown Podzolic soils. Soil Sci. 68: 259-272, 19^ 9 . 13. _________ Major kinds of profiles and their relationships in New York. Soil Sci. Soc. Amer. Proc. 17, No. 2 , 123-127, 1953. lb. Deb, B. C. The estimation of freeiron oxides in soils and clays and their removal. J. Soil Sci. I, No. 2 : 212-220, 19^9. 15. Frei, E. and M. G. Cline. Profile studies of nor­ mal soils of New York II. 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The correlation of soil type and parent materi­ als with supplementary information on the weather­ ing processes. Soil Sci. Soc. Amer. Proc. (19VV) 10: 397, (19^5). 35. Matelski, Roy P. and L. M. Turk. Heavy minerals in some Podzol soil profiles in Michigan. Soil Sci. 6 b : V69-V87, 19V7. 36. McCaleb, S. B. and M. G. Cline. Profile studies of normal soils of Hew York, III. Physical chemi­ cal properties of Brown Forest and Gray Brown Podzolic soils. Soil Sci. 70: 315-328, 1950. 37* McCreery, G. L. Improved mount for powdered speci­ mens used on the Geiger counter x-ray spectrometer. Jour. Amer. Ceram. Soc. 32: lVl-lV6 , 19V9. 38. Mick, A. H. The pedology of several profiles de­ veloped from the calcareous drift of eastern Michi­ gan. Michigan State Agricultural Experiment Station Tech. Bull. 212, 19^939* Mickelson, G. A. Mineralogical composition of three soil types in Ohio with special reference to changes due to weathering as indicated by resistant heavy minerals. Unpublished Doctor of Philosophy Thesis, Ohio State University, 19V2 . VO. Nygard, I. J. , P. R. McMiller and Francis D. Hole. Characteristics of some Podzolic, Brown Forest and Chernozem of the northern portion of the Lake states. Soil Sci. Soc. Amer. Proc. 16: 123-129, 1952. Vl. Phillippe, M. M. and J. L. YJhite. Quantitative es­ timation of minerals in the fine sand and silt frac­ tions of soils with the Geiger counter x-ray spec­ trometer. Soil Sci. Soc. Amer. Proc. (19V9) 15: 138, (1950). 66 Pollack, S. S. X-ray diffraction of common silica minerals and possible applications to soil genesis. Unpublished Master of Science Thesis, Michigan State College, 1953. M3. Redmond, John C. Quantitative analysis uLth the x-ray spectrometer. Anal. Chem. 19: 773-777? 19V7. Mk Rolfe, Bernard M. Pedogenic processes indicated by the mineralogical study of fourteen important soil profiles. Unpublished Doctor of Philosophy Thesis, Pennsylvania State College, 1952. *+5. Stobbe, P. C. The morphology and genesis of the Gray Brown Podzolic and related soils of eastern Canada. Soil Sci. Soc. Amer. Proc. 16: 81-8*+, 1952. MS. van der Marel, H. W. Mineralogical composition of a heath Podzol profile. Soil Sci. 67: 193-207? 19^9 . M 7. Whiteside, E. P. Preliminary x-ray studies of loess deposits in Illinois. Soil Sci. Soc. Amer. Proc. (19^6) 12: M l 5, (19M7).