s 14 .GS: CIR s®£ c. Q. C=HjA SxAfU)U>| STATE OF ILLINOIS WILLIAM G. STRATTON, Governor DEPARTMENT OF REGISTRATION AND EDUCATION VERA M. BINKS. Director GUMBOTIL, ACCRETION- GLEY, AND THE WEATHERING PROFILE John C. Frye H. B. Willman H. D. Glass DIVISION OF THE ILLINOIS STATE GEOLOGICAL SURVEY JOHN C. FRYE, Chief URBANA CIRCULAR 295 ILLINOIS GEOLOGICAL SURVEY LIBRARY JUL 12 i^do 1960 SURVf?,,, 3 3051 GUMBOTIL, ACCRETION -GLEY, AND THE WEATHERING PROFILE John C. Frye, H. B. Willman, and H. D. Glass ABSTRACT Mineralogical studies have been made of the weather- ing profiles of the glacial till plains of Illinois. A comparison is made between profiles developed in situ and those that in- clude accretion-gley. In the upper part of the in situ profiles there is a sig- nificant depletion of the Na-Ca feldspars and garnet and ap- preciable depletion of ferromagnesian minerals. K-feldspar, tourmaline, zircon, and epidote show no measurable effect of weathering. Of the clay minerals in the till, the chlorite and biotite-type micas alter successively to vermiculite-chlorite, vermiculite, mixed-lattice clay minerals, and expandable ver- miculite. Muscovite is more resistant. Compared with the in situ profiles, the accretion-gley s show less mineral decomposition and possess a mixture of clay minerals ranging from chlorite to montmorillonite that in- dicates physical mixing rather than alteration in place. The total weathering effect in all materials studied is strikingly less than that attributed to gumbotil. It is concluded that the term "gumbotil" has not been sufficiently restricted to render it a useful scientific term. Deposits of accretion-gley can be differentiated from in situ weathering profiles in the field, and such profiles should be described in terms of defined zones. INTRODUCTION The surface of the extensive plain of Illinoian glacial till in Illinois is characterized by a strongly developed profile of weathering. This profile gener- ally is covered by loess, till, or outwash. It has a relatively wide range of ex- pression, similar to that of the profiles that occur on the surfaces of the older till sheets of the Midwest. One distinctive expression of the weathering profile is characterized by gray clay and has been named "gumbotil" (Kay, 1916a; Kay and Pearce, 1920). As has recently been pointed out (Frye, Shaffer, Willman, and Ekblaw, 1960), materials that meet the gross physical requirements of gumbotil may have originated in several ways, but probably the most common origin was the slow accretion of fine-textured materials to form a deposit in shallow undrained areas on the initial till plain surface. Deposits of this type, which commonly have been classed as gumbotil, were named "accretion-gley" and the term "gumbotil" was restricted to [1] 2 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 the products of in situ weathering formed where drainage was sufficiently poor to produce gleying. The field relations of accretion-gley deposits have been described (Frye, Shaffer, Willman, and Ekblaw, 1960). It is our purpose here, from mineralogic studies of the sand and finer fractions of accretion-gleys and of in situ weathering profiles developed in the same glacial tills, to determine criteria distinguishing the two types of material and to develop evidence bearing on the origin of the ma- terials. The samples used for laboratory analysis in this study are listed in table 1, which gives also their sand content and solubility in hydrochloric acid. Per- centages of feldspars and heavy minerals are given in table 2, and results of X- ray analyses in table 3. Many of these data are shown diagrammatically in figures 1, 2, 3, 4, and 5. To discuss the positions of samples within the profile of weathering it is necessary to define the subdivisions that are used. In this report standard pedo- logic nomenclature (U.S. Department of Agriculture, 1951) is used insofar as prac- tical. Because our study is concerned with the deeper parts of the profile as well as with the shallow portions, it has been necessary to expand the terminology for this deeper part. In pedologic literature the G-horizon is applied to gleyed materi- al of both in situ development and slow accumulation. To clarify its use in this report, G-zone is applied only to accretion-gley. The following definitions apply to the zones of the profiles as used in this report. Where standard pedologic no- menclature is mentioned, reference is made to the Soil Survey Manual (U.S. De- partment of Agriculture, 1951). A-zone = B-zone BG-zone = C-zone CL-zone = CC-zone Weathering Profile Terminology The A-horizon, with subdivisions of A , A , and A , of standard pedologic terminology. B. B-horizon, with subdivisions of B, logic terminology . brown; contains soil structure, clayskins, and commonly Mn-Fe pellets. It is the zone of clay enrichment. , and B , of standard pedo- Commonly oxidized to some shade of red or A zone that may occur in the position of the B-zone in a profile de- veloped in situ. It may represent a modification of a part of the B-zone. It has clay accumulation but displays only a limited range of soil structures. The reducing environment produces some shade of gray in color. A BG-zone commonly is a secondary modi- fication of a primarily developed B-zone and therefore may dis- play Mn-Fe pellets and some other characteristics of the B-zone. Weathered parent material that generally occurs next below the B- zone, but may be below an A-, BG-, or G-zone. In those areas where the parent material was initially calcareous, the C-zone is divided into a CL-zone and a CC-zone. Leached C-zone. The zone below the B that is leached of primary carbonates; it may be strongly to weakly oxidized, but does not display soil structure. Calcareous C-zone. The zone below the CL-zone (where present) that contains primary carbonates. It is oxidized and displays the GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 3 structure of the parent material. In many sections a subzone occurs at the top from which calcite has been leached but which retains dolomite . G-zone = Accretion-gley . An accumulation of fine-textured material charac- terized by an abundance of clay, derived by slow lateral transport from adjacent gentle slopes (with or without increments of loess) and deposited in an undrained position in the microtopography where semi-permanent water produces a reducing environment. Some organic material may be present, soil structure is generally absent, and in some places indistinct bedding may be observed. The color is always some shade of gray. Acknowledgments We wish to thank George E. Ekblaw, Illinois State Geological Survey, and Paul R. Shaffer, University of Illinois, who have read and criticized this manu- script. Preparation of samples and grain counts of heavy minerals and feldspars were done by James Bloom, John Humes, Constantine Manos, and Richard Mast. Determinations of sodium and potassium of ten samples were made by L. D. Mc- Vicker, and W. F. Bradley assisted in interpretation of the X-ray data. THE GUMBOTIL CONCEPT Concentrations of clay on the surfaces of till plains have been recognized since the past century. The terms "gumbo" and "gumbosoil" were in common use for these conspicuously plastic materials. Kay (1916a; 1916b) pointed out that this type of gumbo material occurred on the surfaces of Nebraskan, Kansan, and Illinoian tills, both where these tills were covered only by loess and where they were overlain by younger drifts. He proposed (Kay, 1916a) the term "gumbotil" for this material, and ascribed to it a concept of origin that he considered appli- cable to all such deposits on all till plains. He defined gumbotil as follows: Gumbotil is, therefore, a gray to dark colored, thoroughly leached, nonlaminated, deoxidized clay, very sticky, and breaking with a starchlike fracture when wet, very hard and tenacious when dry, and which is chiefly the result of weathering of till. The name is intended to suggest the nature of the material and its origin, and it is thought best to use a simple rather than a compound word. Field work has already established the fact that in Iowa there are three gumbotils, the Nebraskan gumbotil, the Kansan gumbotil, and the Illinoian gumbotil. In 1920, Kay and Pearce discussed at length the origin of gumbotil and re- affirmed the 1916 definition and interpretation. They presented data demonstrating that the percentage of siliceous pebbles was higher and the size of the pebbles much smaller in the gumbotil than in the underlying leached and unleached tills. They also described the presence of recognizable boulders in various stages of disintegration in the leached till below the gumbotil (but not in the gumbotil itself), and presented the results of 11 chemical analyses of calcareous till, leached till, and gumbotil. They pointed out a downward increase in the proportion of soluble diffusible constit- uents and a downward decrease in the proportion of alumina. Expressing their ge- netic interpretations, they stated (Kay and Pearce, 1920, p. 122): 4 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 The stratum now forming, deprived of practically all of its sodium and potassium, of most of its calcium and magnesium, and some of its iron and silica, is the present residuum of the whole chem- ical leaching process. This is the gumbotil. In 1929, Kay and Apfel reviewed the earlier work on gumbotil and presented data supporting the previous conclusions. Their confirmation of the earlier work is emphasized by the statement (Kay and Apfel, 1929, p. 112): The resultant residuum of the chemical leaching process is a practically insoluble stratum — the gumbotil. In ad- dition, such physical factors as wind action, freezing and thawing, and burrowing of ground animals may have played some part. In 1930, Leighton and MacClintock reported the results of studies of weath- ering profiles on tills in Illinois. They supported the conclusions of Kay and his co-workers concerning the origin of gumbotil. They proposed a five-fold zonation of the weathering profile on till surfaces, which they called horizons I to V in de- scending order. They described (1930, p. 31) Horizon II as: Chemically decomposed till, composed chiefly of alteration products and resistant constituents of the original till, and strikingly unlike the original till. To this horizon they assigned gumbotil as the product of a poorly drained topography and introduced the terms "siltil" and "mesotil." Siltil was defined as the weathering product of a well drained area and mesotil as the weathering product of an intermediately drained area. Their views concerning the development of the several horizons are clearly stated (1930, p. 35) as follows: Some of the surface and near-surface processes became in- effective with depth but chemical weathering proceeded, the different processes at different rates — oxidation and hydration the most rapidly; leaching of the limestone pebbles and cal- careous matrix somewhat less rapidly; the disassociation or decomposition of the coarse-grained silicates still less rapidly; and, finally, for the oldest drifts, destruction of the more re- sistant fine-grained silicates and the slow solution of the cherts and quartzites. Owing to the different rates at which these four processes operate, the profile on the Illinoian and older drifts came in time to have the four horizons with thin transition zones between them. Their views concerning the relation of gumbotil to Horizon II are further amplified (1930, p. 37) by the statement: Attention has been focused by many pedologists on the common presence of a plastic heavy subsoil zone in partially drained profiles which they account for by illuviation. This is not to be confused with the gumbotil which is largely the product of decomposition in situ in poorly drained areas. Subsequent to the 1930 publication by Leighton and MacClintock, relatively little new data have been presented concerning gumbotil. Pedologists generally GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE ' did not oppose the concept, although a few presented some objections to it (Kruse- kopf, 1948; Simonson, 1954). On the other hand, writers of geology textbooks have completely accepted the early concepts of origin and have treated them as established facts by referring to the B-horizons and the gumbotil as zones of nearly complete decomposition of silicate minerals. In recent years a few papers (Gravenor, 1954; Ruhe, 1956; Brophy, 1959; Allen, 1959) have presented additional mineralogical data on weathering profiles (including gumbotils) in till. Critical examination indicates some of these data are incompatible with the previously developed concept of complete chemical weathering of silicates in gumbotil. Ruhe (1956, p. 449) noted the occurrence of slopewash or accretion deposits in the upper part of humic-gley profiles on till in Iowa. In 1960, in a review of the field relations of gumbotil, Frye, Shaffer, Will- man, and Ekblaw concluded that material meeting the requirements of the empirical definition of gumbotil has been formed in several strikingly different ways. Even here, however, because of lack of significant mineralogical data, the notion of extreme decomposition of silicate minerals in in situ weathering profiles was not challenged. SUMMARY OF INTERPRETATIONS A critical examination of the mineralogical data shows that the concept of gumbotil origin is fallacious in several respects: 1) In neither the B-zones of in situ profiles nor in the accretion-gley layers do the silicate minerals approach the stage of complete decomposition. Only a moderate decrease in the abundance of feldspars and other silicate minerals occurs. 2) At most, only a moderate decrease in sodium and potassium occurs in the B-zones and the accretion-gleys. 3) The small size and scarcity of pebbles in many materials called gumbotil (accretion-gley) is the result of mechanical sorting of a material from which the carbonate rocks have been removed. 4) The addition of clay to the B-zone can be accounted for only by down- ward movement of clay. The feldspars and other minerals that might have yielded additional clay are largely still present in the B-zone and although the clay minerals originally present are altered this change does not add to the total clay. The in- crease in clay content occurs entirely in the less than 0.5-micron size, another fact that favors downward movement of the additional clay. 5) In the in situ profiles there is a progressive alteration of the clay min- erals, whereas the accretion-gley contains an assemblage of clay minerals of strikingly different degrees of weathering, suggesting a mechanical mixture. 6) The data suggest that in general the degree of chemical weathering, as measured by depletion of feldspars and ferromagnesian minerals, is greater in well drained than in the poorly drained areas. The mineralogical data confirm the earlier conclusion (Frye, Shaffer, Will- man, and Ekblaw, 1960) that the weathering profiles developed on the surfaces of the till plains of Illinois are of two major types: 1) in situ weathering profiles, and 2) accretion-gley deposits. The term "gumbotil, " although in some places applied to the partially gleyed BG-zones of in situ profiles, has been widely used for the accretion-gley deposits. The most important mineralogical changes that occur when tills weather in place result from: 1) removal of the carbonate minerals progressively downward; 2) alteration of some of the existing clay minerals; and 3) the downward illuvial movement of some fine clay into the B-zone. ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 cminHJmrjTn^ tan weathered loess dark brown weathered loess oxidized G-zone *• road grade co ROCHESTER SECTION (ILLINOIAN) dark brown weathered loess BG- zone HIPPLE SCHOOL SECTION (ILLINOIAN) Fig. 1 - Generalized field sketch of relation of Rochester and Hippie School samples to zones in weathering profiles that contain accretion-gley . Accretion-gley deposits that commonly have been classed as gumbotil are the product of slow accumulation of predominantly fine-textured material in poorly drained or undrained areas on the constructional surface of the till plain left after retreat of the glacier. In some places minor increments of aeolion silt may have been incorporated into the accretion-gleys. However, the striking similarity of the mineralogy of the silt and sand sizes from the accretion-gleys to that of the A- and B-zones of in situ profiles of weathering indicates that the predominant source of accretion-gley is in the adjacent gentle slopes of weathered till. The relatively large percentage of montmorillonite in accretion-gleys has been considered evidence that a large part of the deposit is derived from loess. However, the similarity of the mineralogy of the silt- and sand-size fractions GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 7 of the accretion-gleys to that of the till profiles, the common presence in the ac- cretion-gley of small, scattered pebbles that are derivable from adjacent slopes (but not from loess), and the stratigraphic position and geographic location of the deposits with respect to known identifiable loess deposits argue against such a hypothesis. When these data are added to the field data, including the occurrence of lenses of accretion-gley in a down-slope relation to slopes (fig. 1) locally dis- playing pebble concentrates, the postulated origin of the accretion-gley as a pre- dominantly sheet-wash deposit, derived largely from adjacent slightly higher areas of the till plain, becomes inescapable. DISCUSSION OF DATA The Illinois State Geological Survey is engaged in a broad investigation of the mineralogy and petrology of the Pleistocene deposits of the state, of which the present report is one part. Data are reported from 193 samples from 61 localities in Illinois; 124 of these samples are from Illinoian age till and the remainder from tills of Kansan and Wisconsinan age, the latter including both Altonian (Winnebago) and Woodfordian tills (Frye and Willman, 1960). Included in the samples are 42 for which analyses were published previously (Brophy, 1959; Willman, 1942) and for these only the supplemental data are presented here. Many of the variations in the feldspar and heavy mineral percentages in the weathering profiles result from variations in the till before it was weathered. In some localities these original variations appear to be as great as the extremes pro- duced by weathering. As a result, generalizations are based on averages of many samples (table 4) and specific examples are presented from selected localities in which progressive mineralogical changes indicate a relatively uniform mineral dis- tribution in the original material . Mineralogical data are pertinent to an evaluation of weathering effects when examined in terms of vertical variations throughout the profile. Such an evaluation may be made by use of the composition of the unaltered till below the profile as a standard of reference. Further comparisons may be made between dif- ferent points in the profile by use of other standards of reference. To make such comparisons the following equations were used: ^ x ^ = Z X2 Yl 100 - Z = percentage of depletion where: XI = percentage of reference mineral in reference zone. X2 = percentage of reference mineral in zone being analyzed. Yl = mineral being tested for depletion, percentage in reference zone. Y2 = mineral being tested for depletion, percentage in zone being analyzed. For example, using the data from table 4 and calculating the depletion of Na-Ca feldspar in the A-zone, using K- feldspar as the reference mineral, and the CC-zone as the reference zone, the depletion is as follows: 12 5 — x — = 0.68 = 68 percent remaining 11 o 100-68 = 32 percent depletion 8 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 Carbonate Minerals The content of carbonate minerals and rocks in the unaltered Illinoian till is generally between 20 to 30 percent; in unaltered Wisconsinan tills it is some- what higher. The carbonate minerals, generally more dolomite than calcite, have peaks of abundance in the pebble and silt sizes. They have minima at the peaks of abundance of other minerals, particularly where the carbonates are diluted by clay in the clay fraction, by quartz in the sand sizes, and by igneous and meta- morphic rocks among the boulders (table 3) . The greatest volumetric effect of weathering of glacial till has resulted from the solution of the carbonate minerals. The only processes that are observable at somewhat greater depths below the sur- face of weathering are oxidation and beginning alteration of some clay minerals. In the upper few feet of the CC-zone there is commonly 10 to 15 percent less soluble material than in the lower part of the zone, and X-ray determinations indicate that almost all the carbonate present in the subzone is dolomite. No con- spicuous line of demarcation distinguishes the base of this subzone, and, despite the considerable reduction in volume, no significant structural change is involved. In the field, the presence of the subzone is detectable by its slow reaction to acid. The presence of a subzone of partial leaching is predictable because of the great differences in solubility of the carbonates. Laboratory experiments show that in a given sand size, the calcite of a prepared mixture of calcite and dolomite can be completely dissolved by hydrochloric acid without significant loss of dolo- mite. The subzone has been considered to be very thin in soil profiles on tills. Several samples collected to represent the calcareous till fall within this subzone rather than in the entirely unleached material (table 3) . Feldspars The feldspars generally are recognized as minerals that are subject to chem- ical decomposition as the result of weathering processes. Goldich (1938) showed that in the pre-Cretaceous weathering of a granite gneiss in Minnesota the Na-Ca feldspars are highly susceptible to weathering and are largely depleted before the K-feldspars are affected, but that as weathering proceeds the K-feldspars also are removed, leaving a predominance of kaolinite and quartz. The feldspar content of the silt and sand fractions should, therefore, serve as an index to the degree of weathering in the till profiles. Another advantage in using feldspars as indices is that their original abundance decreases only moderately with increasing size. For example (table 2), the abundance of the K- feldspar from the very fine sand fraction averages 13 percent, from the fine sand fraction 11 percent, and from the medium sand fraction 8 percent. In the fine and very fine sand fractions in unaltered Illinoian till (fig. 2; table 4), there is an average of 11 percent K- feldspar and 10 percent Na-Ca feld- spars or a total of 21 percent feldspar. Proceeding upward in a weathered profile, the CC-zone averages 20 percent, the CL-zone 21 percent, the B-zone 18 percent, and the A-zone 16 percent feldspar. The change is progressive throughout the • profile without regard to the boundaries of the zones. In five sections where closely spaced samples were available, the uppermost sample in the CL-zone averaged 20 percent feldspar and the lowest sample from the B-zone averaged 21 percent feld- spar. Relative to quartz this represents a depletion of 12 percent of feldspar in the B-zone and of 24 percent in the A-zone. The average feldspar content for the accretion-gleys resting on Illinoian till is 18 percent, the same as for the B-zones of the in situ profiles. GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE Na-Ca Feldspar Tour.+ r-K- Feldspar |*Epidote 1 \ x^/ .6 0/ <*' ■Hornblende \ vtv \ \° » \ % ILLINOIAN A' i A? I 10 20 30 PERCENT 40 50 60 G A L 111 Ld > _l < LL. O ~z. cc CL CO ^BG LlI _l CL 2 Ll < O CO u. o o N cc 22 9 < °= 31 cc Ld CO 25 unoxidlzed 12 TOTAL 124 Na-Ca Feldspar Feldspar -Epidote ^Hornblende 10 20 WINNEBAGO 30 PERCENT 40 \ 50 \ \ \ *A A I o G A o cc CL B -CL I £/ J? 7 _L L / cc LU CD < CC Ld > < CO LU < co cc LU m 60 unoxidized TOTAL 2 27 Fig. 2 - Average values for mineral constituents of the several zones of in situ profiles developed on Illinoian and Winnebago tills. The average composition of accretion-gleys is shown by bars at the top. 10 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 20 PERCENT 30 40 50 60 x i ' > ," 1 1 ... , , \\ \> """"--.... \ r- i .■ ^ -■* *"* \ i^---^ ^ *** * '. \ ° 1 1 o.' ul 1 o • 1 1 ? "- -S v.m 8 15 V. \ ol | ' ■X * ! i ;\ ^\ TJ 1 C | J si c ' o! 1 : v \ X cc KEWANEE SECTION (ILLIN0IAN) -313 -312 ILLITE EXPANDABLE VERMICULITE MIXED LATTICE CLAY MINS VERMICULITE 101 - 15 - 20 10 20 — I — PERCENT 30 40 t / \/ ^s _ j> >», 1 \ _-- ■•\ \ \ ■ M \ * / \ s \ / f o. \ \ \ / <>/ 7?' \ 1 FAIRVIEW SECTIONS (ILLINOIAN) ILLITE 1 L EXPANDABLE VERMICULITE MIXED LATTICE CLAY MINS. CC i II 10 20 PERCENT 30 ILLITE - MONTMORILLONr EXPANDABLE VERMICULITE MIXED LATTICE CLAY MINS ttt / 2 y 6uj 40 50 60 1 1 !/ 1 1 i i i \ • / si \ */ ^T^6/ 9 . . • V <*/ o\ ^^ \ 1/ -• \5 / / \ \ \ \ \ EXCELSIOR SECTION (WINNEBAGO) -713 MONTMORILLONITE VERMICULITE - CHLORITE I I J I - 6 Fig. 3 - Values of selected mineral constituents in Kewanee, Fairview, and Excelsior sections. Sample locations are given in table 1, and quantities given in tables 2 and 3. GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 11 Most, if not all, of the feldspar depletion is of Na-Ca feldspars (figs. 2, 3), Assuming the K-feldspars to be constant, there is a depletion of 25 percent of Na- Ca feldspars in the B-zone and 31 percent in the A-zone. Compared with the av- erage calcareous till, the accretion-gley shows a 42 percent depletion of Na-Ca feldspars but an increase of K-feldspars. As is shown by the Kewanee section (fig. 3), the Na-Ca feldspars decrease progressively upward through the CL-, B-, andA-zones. However, this relation- ship does not obtain in the accretion-gley sections (fig. 4). In contrast to the weathering profiles of the Illinoian till, the profiles on Winnebago (early Wisconsinan) till show relatively little depletion of feldspars except in the A-zone. The averages show 31 percent depletion in the A-zone but only 5 percent in the B-zone. The samples of accretion-gley on Winnebago till show a percentage of both Na-Ca and K-feldspars as high as that of the calcareous Winnebago till. Clay Minerals The clay mineralogy of all samples was determined by X-ray methods and the results are given in table 3. The terms chlorite, kaolinite, illite, and mont- morillonite are used in the generally accepted sense. The terms vermiculite and vermiculite-chlorite, mixed-lattice clay minerals, and expandable vermiculite refer to a transitional series of alteration products, derived primarily from biotite-type micas and chlorite. Chlorite alters first to vermiculite-chlorite, even below the depth of carbonate leaching (Droste and Thoren, 1958), then to the partially ex- pandable mixed-lattice stage, and finally to the expandable vermiculite stage. Biotite-type micas probably alter through a vermiculite stage to the expandable vermiculite stage. Examples of the major types of X-ray patterns are shown in figure 5 . This alteration sequence can be confirmed experimentally. The saturation of expandable vermiculite materials with magnesium chloride produces vermiculite that is not expandable with ethylene glycol. The unaltered Illinoian till is characterized by the presence of illite, chlor- ite, and kaolinite, with or without primary montmorillonite . Unaltered Winnebago till consistently contains montmorillonite in addition to illite and chlorite and lacks kaolinite, whereas the unweathered tills of Woodfordian age, except in their out- ermost moraines in northern Illinois, are predominantly illite and chlorite and gen- erally lack kaolinite and montmorillonite (fig. 5, sample 390). The clay mineral assemblage in the CC- zone strongly resembles that in the unaltered till. However, in the profiles on Illinoian till (and in a few samples of till of Woodfordian age) some of the chlorite and biotite-type micas have been altered to the vermiculite-chlorite and mixed-lattice stages. In the CL-zone on Illinoian till unaltered chlorite is not detectable, and the zone is characterized by vermiculite, vermiculite-chlorite, and mixed-lattice clay minerals (fig. 5, sample 314). The amount of these alteration products ap- pears to increase upward through the zone, but illite appears to have approximately the same abundance as in the unaltered till. The B-zone on Illinoian till is characterized by the absence of biotite-type micas and chlorite which have entirely altered to expandable vermiculite (fig. 5, sample 329). There is a significant decrease in illite, and the kaolinite appears unchanged. In the till of Woodfordian age the B-zone shows no loss of illite, and the alteration of biotite-type micas and chlorite has progressed only as far as the 12 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 PERCENT 30 40 4 u u. x Si- ll. UJ 10 ROCHESTER SECTION (ILLINOIAN) MONTMORILLONITE 10 20 PERCENT 30 40 50 60 '-£ x: • o a -p p 1 — 1 -p N O ECU c 4-1 -P c O X CD o c ■i-l CD CM -H h ^^ •H S N 1 -P C 03 to • O XI -H O •!"< D-^H U3 -P C ^H C to c CD CO 03 4-1 CD CD 4-i O CD CO o x: ^ cd 4-1 -H O ■-< c •H X! 1 SW NE SE, 20-3N-8W, Madison Kansan CC 4 + 2 33 23 2 do. do. CL 1.2 0.8 41 9 3 do. do. B 1.3 0.5 28 9 13 sw SE NE, 31-3N-6W, Madison Illinoian B 3 + 1.5 38 1 16 do. do. B 2 1 42 16 24 SE SW NE, 10-5N-10W, Madison do. B 2 2 34 7 26 do. do. CC 23 8 30 9 57 SE SW 13 -4S-4W, Pike do. B' 39 5 60 SW SE 9- 4S-4W, Pike do. B 3 + 1 49 11 61 SE SW 13 -4S-5W, Pike Kansan CL 5 3 57 4 94 NW NW NE, 23-18N-7W, Menard Illinoian CC 10 8 39 27 97 Cen. E line, 11-18N-11W, Cass do. CC 2 57 26 98 do. do. B 3 1.5 29 5 113 NE SE NE, 10-6N-5E, Fulton do. CC 5 + 5 37 20 114 do. do. CL 1 1 60 5 119 SW SW NE, 31-7N-6E, Peoria Kansan unox 25 22 120 SW SW NE, 31-7N-6E, Peoria do. CC 29 26 34 27 123 do. do. CC 29 9 28 23 124 do. do. B 4 2 57 9 125 do. Illinoian CC 29 26 21 25 126 do. do. CC 29 1 32 33 131 Cen.,31-26N-3W, Tazewell do. CC 5 + 3 19 29 132 do. do. G 1.5 1 58 6 138 do. Shelbyville unox 18 33 139 SE NW SW, 12-26N-4W, Tazewell Bloomington CC 10+ 1 42 35 145 SW NW NE, 1-25N-2E, McLean Shelbyville CC 8 2 36 33 146 do. Bloomington CC 3 1 26 31 148 do. Normal CC 3 2 12 26 170 NW NE NE, 31-36N-12E, Cook Valparaiso CC (Sampl R.I. e 102, 79)* 171 NW NE SW, 9-34N-4E, LaSalle Bloomington CC (Sampl R.I. e 104, 79)* 58 13 172 NE SE NW, 10-5N-3W, Bond Illinoian CC (Sampl R.I. e 105, 79)* 44 26 173 SE SE NW, 36-18N-11W, Cass Illinoian CC ( Sampl R.I. e 106, 79)* 33 28 180 NW SW NW, 31-8N-3E, Fulton do.(F-l) unox 6+ 5.5 27 24 181 do. do.(F-2) unox, 6 + 3 23 27 182 do. (Samples 180-251 were col- do.(F-3) unox 6+ 0.5 18 22 lected by Brophy (1959). 183 do. His sample nos. appear do.(F-4) CC 9.7 9 14 30 184 do. in parentheses in the ag ? do.(F-5) CC 9.7 4.5 17 24 185 do. cc >lumn. New data are do.(F-6) CC 9.7 0.5 19 23 186 do. given here. ) do.(F-7) CL 2.5 1.5 28 7 22 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 Table 1. - Continued Sam- ple no. Location ■5- sec. T. R.j County -p c Ol fH (D 4-. -H O (H OJ Q) +J O* ro < 6 4-. OJ O --I 0) Mh c u N Q. 4-1 05 • <££ 0) x; +-> c •H -a c U) 4-. O N •H CO C • tH g +-" 5 O CM U 1 H-i % of the -2 mm. size fraction soluble in HCl 188 do. do.(F-9) B 4 3.5 20 189 do. do.(F-lO) B 4 2.5 14 190 do. do.(F-ll) B 4 1.5 12 7 191 do. do.(F-12) B 4 1 11 192 do. do.(F-13) B 4 0.5 11 195 Cen. 6-7N-6E, Eff ingham do.(E-l) unox. 7.5 + 6 32 28 196 do. do.(E-2) unox. 7.5 + 3 31 24 197 do. do.(E-3) unox. 7.5 + 0.5 38 29 198 do. do.(E-4) CC 1.6 1 35 23 199 do. do.(E-5) CC 1.6 0.5 39 19 200 do. do.(E-6) CL 1 0.8 40 8 201 do. do.(E"7) B 5.1 4 41 202 do. do.(E-8) B 5.1 3.5 40 203 do. do.(E-9) B 5.1 2.5 33 5 204 do. do.(E-lO) B 5.1 2 31 205 do. do.(E-ll) B 5.1 1 29 206 do. do.(E-12) B 5.1 0.5 29 207 do. do.(E-13) A 1.9 1.5 31 208 do. do.(E-14) A 1.9 1 31 209 do. do.(E"15) A 1.9 0.5 30 239 NW SW NW, 31-8N-3E, Fulton do.(F-2) unox . 6 + 3 240 do. do.(F-2) unox . 6 + 3 241 do. do.(F-5) CC 9.7 4.5 242 do. do.(F-5) CC 9.7 4.5 245 do. do.(F-ll) B 4 1.5 246 do. do.(F-ll) B 4 1.5 247 Cen., 6-7N-6E, Effingham do.(E-l) unox . 7.5 6 248 do. do.(E-6) CL 1 0.8 249 do. do.(E-7) B 5.1 4 250 do. do.(E-ll) B 5.1 1 251 do. do.(E-13) A 1.9 1.5 291 NE NE, 22-23N-9E, Ogle Winnebago G 4 + 3 11 7 292 NE NE, 22-23N-9E, Ogle Winnebago G 4 + 1 14 7 293 NE NW NW, 36-27N- ■6E, Stephenson Winnebago G 2+ 2 28 9 294 NW NW SE, 9-23N-8E, Ogle Winnebago G 12+ 2 12 6 312 SW NW NW, 15-15N- ■5E, Henry Illinoian unox .10 3 24 35 313 do. do. CC 12 2 17 21 314 do. do. CL 0.7 0.5 19 7 315 do. do. B 2.5 1.5 23 4 316 do. do. B 2.5 0.5 20 5 317 do. do. A 2.5 1.7 20 5 318 do. do. A 2.5 0.5 14 11 GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 23 Table 1. - Continued a> 0) C '-^ x: • o a +■> g •— 1 +> N O ecu c «H +> c O I o> O c •h ai CM -H M •H 5 N 1 -P c ro U) • o TJ -H O -H Q.-H (0 +J C ^H C mh o a> (0 o x: m a> Mi Tt O •— 1 C ^-' •H XI U) • -H VH H Sam- Location O U •H J2 -t-> § +* Xt 0) -M c o •H c U) -P o nJ O N ^H -% sec. T. R. , County < 6 O h n a x: o <£^ ^ 1 <4- •H O ^ 0) U) 320 NE NE SE, 26-15N-5E, Henry Illinoian G 5 2 16 9 327 SE NE NW, 36-8N-2E, Fulton do. CC 8 1 30 18 328 do. do. CL 2 1 25 11 329 do. do. BG 2 1 41 11 330 do. do. G 3 2 15 6 a 331 do. do. G 3 1 35 7 334 NW SW NE, 5-14N-4W, Sangamon Illinoian G 8 2 3 335 NE SE SE, 4-14N-4W, Sangamon do. CC 5 4 29 29 336 do. do. CL 4 3 46 5 337 do. do. B 3 2. 5 22 6 338 do. do. B 3 0. 5 34 7 339 do. do. BG 2.5 1. 5 20 11 340 do. do. A 3.5 2. 5 21 6 344 SE NW SE, 23-25N-6E, McLean Cropsey CC 4+ 0. 5 8 33 345 SE NW SE, 23-25N-6E, McLean do. B 1.5 0. 5 11 14 348 NW NE NW, 9-23N-4E, McLean Normal B 23 14 357 NW SE NW, 6-21N-4W, Mason Illinoian CC 10 2 28 21 358 do. do. B 1.5 0. 8 23 11 365 NE SW SE, 12-25N-5W, Tazewell Illinoian CC 8 4 • 22 28 369 NW SE SW, 18-15N-10E, Bureau do. CC 20 18 19 26 372 SE SE SW, 15-16N-10E, Bureau Arlington CC 10+ 2 20 39 374 SW SE SE, 22-16N-10E, Bureau Illinoian unox. 5+ 2 37 32 376 do. do. CC 7 2 33 29 377 do. do. CL 2.5 1 32 6 378 do. do. B 1.5 0. 8 17 12 384 SW SE SE, 27-16N-10E, Bureau Bloomington CC 4 3 23 34 390 SE SE SW, 36-34N-4E, LaSalle Marseilles CC 10 3 7 39 391 SW SW SW, 14-34N-8E, Grundy Minooka CC 3 + 2 9 40 394 SW SW SW, 5-36N-12E, Cook Valparaiso CC 5+ 1 7 30 395 do. do. B 1 0. 5 12 15 400 SW SW SW, 1-37N-12E, Cook Tinley CC 5+ 2 6 29 401 NW SW SW, 19-43N-9E, McHenry W. Chicago CC 4+ 2 34 48 402 SW SW NE, 29-43N-8E, McHenry Bloomington CC 22 42 403 do. Gilberts CC 33 38 404 do. Marseilles CC 6 31 405 SW SW NW, 12-44N-5E, McHenry Marengo CC 5 + 2 26 45 407 NE NW NE, 28-46N-17E, McHenry W. Chicago CC 3 1 38 48 408 SW NW SW, 1-46N-5E, Boone Shelbyville CC 1 + 1 25 38 409 do. do. CL 0.5 0. 2 39 28 410 do. do. B 1 0. 5 40 10 411 NE SW NW, 32-46N-3E, Boone Winnebago CC 7 + 1 40 40 412 do. do. CC 7 + 0. 1 49 16 413 do. do. B 2.5 0. 5 54 5 415 SE NE SE, 11-46N-2E, Winnebago Winnebago CC 10+ 1 49 34 24 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 Table 1. - Continued Sam- ple no. -± sec. Location T. R., C01 jnty +■> c CD h, co (X •-< CO Mh -h h CD CD -p Oi co < 6 4h CD O i-H • H CD 4h C O O (H N Q. O • U) 4-> CD 4h O CD •H C JZ H N CD c — - O Q. N O c •H 3 C ■-! O CD +> • H • co -P a) JZ +-> c ■H -O c ro C '-^ x: . a 4-> E ■— 1 +-> N O ECO c ■4-1 -l-> c O X O) O c •H 0) CM -H u ^-^ •H 3 N 1 -4-> C rO • O T3 -H O -H 0.--H in +-> C ^1 C O c OJ n3 rO M-4 0) OJ M-. 1) fO £ h OJ <+H .H 1-1 c >—• •H X) 0) • -H 4J>hH Sam- Location O M ■ H j^ +-> S. + J X) a> 0) 4-i aj • rH . Mh S O ■+h -H to CD c to 0) Q. a o> z ^»H U) •H O 6 H 1 o> •O H -P Q. 1 t— ) to x:^ i^ 0) Q. a> ^ 10 •H J N -P u fO cr to (H 0) x: s of 0) 0> 0) <-< C 0) O 01 1— 1 H xi x ro 0) •H O H x: x: m 01 s Q. >• C 6 Q. •H to E CD i -a >«-^ c c > -P H Oi ro C O ^ o> 0) X X! x: o M 1 CD -P X •H) +J c a a o 0) — ' ai T3 h to i Q. H -P 05 CO 0) C O C 03 H i ^-> H c •H O N O H 1 o> 3 tO C O e -h H i— i >• id > u (0 If) 0> o> ■— i x: ^ x: to h s 0> CD o c -^ o-.h o to E to c* Q. i—l o ca c o • rH If) •P •—< o to to >. H M > o> ^^ to c a> .h c X e •H o to in c CM o • •H i -P CM o *> \D to O h • 4h 1 e CD • CO f-H O 03 a c f- if) vOOO ro r-ivO^OiniT) O 0>0i(l h t^ O ^i vO h \0 in CO CM O r-i O — i vor-f-oo^- oor-o^^o in r> ^ in 't r- r- r- oo in r- oo co r- vo r-oor- o cm in r> cm •^■voooon r-oo^o^ CM rH H H H _| H .-H ^-, ^H _, ^H ^, in Hin h o I s - in >o vo r- in o o r- md cm cm .-i t- hod n-o ooovoo^h >£> r- r- r- co r- co r- oo r- <£> r~- r- r- co cm co tn in o .-h o o cm in ioo ^ hh •-H CM ■— I CM •— I >-l •— « Hfor-OH o cm oo in r- r- r-- r- co oo r- r^ oo r~ r- ro cm co vo ce oocopio f~ CM CO r— t — r~- vOCMH^f COhvO H\D CO CM \D C-- 00 in ^ H CO o \D M - O 00 H O CO ^ CM h HCO (OCOCM r- ^n \o in co r- oo o <3- oo \oo^inr~ \ococn h cm cm h h oo \o ^ in in cm iocm cm o oo^^— i o o co o r- HHHCO^f CM 'ST HintOH vo co oo cm o h H h CM i-H h CM v£> 00 CO CO ■* \o in vo vo co in co o CM CM -i CM CO in in 't r~ — i -< CM CM CM vO O CM inOM3CMC0 CO CO h ^ CO H I CN CO H (M h h CM (O H O 00 ^ CM ■^•^r-oo in invoh cm ■«■ h h nin co i r- co r- vo in o cm ^-i .-< ^ ^ ^ ^ i—i <— i o 'JOho^ co>j(Mhh inanjHCM o^ncor- CM hhCMh H^fCMHCM (O CM h (O h CM h h r- r- oo r- voocooco cMco^in to cm ^ in ^t in vooi-ico^inor-oooooooin^naovOvOco H HCM H H H H H 00 CO 't (M H HH .-H .— I i— IH H o ^h^ m oo -tfoooooo-nooinoo O l^hCJNvOMJ >OO0 CMOvOr- > CM^CMvOCM CO 'ST in CO -h CM.-iCMvOr-- in^Ht~~vO'>^ hCMhhCM CMCMCMCOCO CMCMhhCM h^^h^hh ^h^^h^^, h^i CO h CM00 00 vO ^\Or-O^H M'r-C0CO'<3- OOCO 'fif) >0 HCM OO O ifivOCOOH hh CMCMinvOvO oavo^n^-i hcmcm cmcm cm oo ro oo co ■* *t •<* r- r- GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 27 r~covO cm^o^ovO o o o co -=t co in oo co co \o in ^r cm h cm co in ■ t^vot^vovo oo r- n ^ o .-i co ^ cm t~~ cm^ in in >o in co in r~ in in h inw n in n in oo co o o o 01 t combo-j in r^ in -^ in n r- r-r-r-r~-r- r- r> r- r^ r-* vo v£> r> r- r- t— r- r- co co oo r~ r- r-~ r> co t^ oo r~- oo r^ co o (XI , — , ro sf o r— , CO CT> r-n in o 0) .— 1 ^T CO (1) 1 ' n o •—< e x; <0 Q. St CO CO o ■-< ■—1 H c m o in CM tO X» -p CO -o CM 1 (0 O h a 0) OJ C *H 6 a> o vO >» (0 .— I 1— 1 > oj in X CM vO r- CNJ .—i o o in a> J3J2X3 X! X> .Q .Q .Q XI XI XI Xt XI X! XI XI XI XI XI XI XI XI XI H X! i3 J3 O T30T30X1 T3T! 00 00 M3 O vO ^f vO CD^O M- COCOCOCO00 00 00 O 00 O r~ 00 00 v£> in in vO vO MD O .-I vO 00 ^ sj- cn o o hoi o M' in \D co oo hoi in »of- cooo h cm oo >^ in md r- oo o o o h oi in ^ r- oo r- r> oo co co aooooooooo oooooo ooooo ooooo ooooco -3- m- m- ^i- 'J o. en <+H If) •H .-J N H-> rH 03 3 cr CO rH cu JZ 4-> . O (/)* CU <" rH a> 0) o c r-l xi cu CO h .rH x M cu jz o CU jS a b c •rH s 6 cu >-ir i -a > ■£ c c « £ M cu cu ^ o ■-< ■*= S X X! +-> s 1 CU (- Q. •H 4-> CD ' Q. o U UJ T3 CO a 1 05 u +-> c 03 CU 03 O C M H 1 u c •H O 1 rH 1 0) 3 03 C O e -h H ■—1 >- > CU 0) ^H 4-> o cu a> _* 3 c o CT-H 03 ^ rH a. o co. c o • H If) +-> •—\ o 03 03 >. u rH > ai <+- #>. 03 C CU .H C x e •H Oo) in c CM o • • H 1 H-> CM o ^R vO 03 o u Hh 1 E CU • 03 r-l O f.O D, C r^rO-tf^H^H CMl CM f~- CM CM "tf vO ClHO I (M CO'^CM'^-CM CM CO CO I CM noj f h vO r-i r-- o rH oo o co .-h -o o in cm oo no\f ^) in 'j o in in oo r— i CM •— i .— i ■— I .— i r-l oor^cocMo cor- oo cmcmcm ^r r-i co o o rn vo o ^ co o r- in oo t «-< C\| _l r-H r-l _l —I rH — I -H _| ,_« -H ,_, _< ,H ^^h^h^^h^^CM CM CO ■* O •ST co oo oo r~ r- O O rH rH CM 'j in in o o CM CM CM CM CM 00 CM in r- co r- vo r» r- f- o -h vo co 'tf co r- t— co co o oo o co co r- r~ co r- co r- o m- ^n o r- r~ r- oo ^o I co I CM I CM I ■} I Ol r- 1| I . — I . — I I -^J" _f _t VO I CO OOCM COCM^I^l- M-CMCOI I 'tflCMCMCM COCMCMCOOO IvOincoCM cmco Hinh i h i~-t--oovo co^rr-coco -y-cMCJcoin cn r hh ^t ^rco inoo^r •* ^-^-voinvo incMco^^ covoinroco n^vovo ^ in oo ocovoit^ inininvor- in^no^-r- ^-vOcovocm o neon > CMCM CMOOCM CM CM^-i— iCM-h ^hCM^hCMCM CM^hCMCMCO 'J h h h (M r~CM f-i o \o i •— i 'f o (N r r co\or-o— i h ^cr cm \o m occvooo 1-hCM H (\| .—I ^H^H^H^n^H ^H^-ifNg^n^H (\| H H CJ H CM ^-t ■— I in oj inr-cMi.— i Oi-iin^ni ^noor~-r^ •^■cosrinco o h cm in cj r-J ^H CO ^H r-H ,-1 coco i oo cm i ^r nn-jvo i in i o^tin ^cMvocMr- cotcmioo r~ o oo cm r~- o vo »-i t-H cm ^h ^ o in 00 O CM vO CM •^ 00 CM CM 00 r- o o cm ^? CM CM 00 CM CM \D O O O 00 CM CM ^n CM 00 vO 00 00 r- 00 00 ■-< •-< •— I -H CM vO ^H in co oojh ciinnoo cm h in in m in in o cm ^H •— I r— 1 r—\ rH rH rH CM r-l CM rH CM CM < en 00 ^f CM CM CM o cr> ■— i ^h .— < CM CM 00 00 00 CJ < cm co ^r in in pq u in in vo r~ CO 0000000000 0000000000 o r- oo o o CM CM CM CM 00 00 00 00 00 00 rH ^r in vO r- oo oo oo oo oo CO 00 00 00 00 GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 29 co cm — i if in onoi in o if vo ■-< cm cm vo r- cm —i co in in —i —i cm co if — i cm cm i ^ ro cm m h>o co co vo cm co r~- o o \o in vo r- co o t-- in h h o o co co in in c~- o o r~- in vo r-- ^o vo r-- ir r~ in ir oo if cm r- oo (N * h o o co cm cm cm n h h h co co o ir vo co if) wocm o co in if co co o p o ,-H ^h ^H ^n HHH PlH ^-| CM — I ^H ^H CM CM CM CM -H CM ^ ^ —I ^ CM OJ nH rH CM — I ^H —I ^H ^H ^H CM CM co m? cm in in in co co r- ^ if o r-- o lOnomo ■3-t^oooco cm co co ^ cm in co f-coh no to 00 r^ t^ t— vo \o r- r~- vo \C> r- \0 r- r- r~ >o 10 in h vo ^ 00 r- r- vo ^o r- 00 r- r~-r^r-t~-r~ r- ^o ^o I^HICMl — i I I CM vO CM H OvO O if CM CO I —l CO if CM —< in "f CM I c in ^ nvor-M) n o co o r^ 00 o in co cm h >o co ^ o it c>cm in in h o^i o ^t ro cm o vo r-voinvoin vo in vo if \o \o \o in in \o r-~ if in vo vo vo vo invoo in vo voin^o if vo in oovo^-oo^h cMorovOin if r~- co co o noiitoo in cm oo co vo nh ooh^o -1 co r- co co o in co CM COCO H h ,_, CM CM — < CM CM — i .-h CM — i CM CM CM CM .-h hCM h hh h h CM h h CM — i — i — i — i ^-i r-* ^h h cm in r- h o if if \0 ^o o o co o o co t- if to cm vo vo co in r-- coo m- o h ^Hinr^-r-vo o cm r- CM CM CM — I — I —■< — I r-H — I .-H — 1 —1—1 —1—1 ,— ( .-H ,— | ,_| ,_) — 1 — 1 CM — 1 ^H IT) CM vO ^ f I hOI I h —i I CM vO CO i-ii.-h.-i —< — i "tf O O r-i h CM CO CM CO — i — i — i ^h CM— i— i CO CM CO CM CM -O CO I O I — i CM — II— i CM — i — i I ,-h —i —i if CO CO I o co if r- in vo — i o co co h in f cm o if — i — I — I CM CO CM —i— i CM — ( CO if .— i co — i vo o cm o •^•vo\or~-in 00 r~- o o o coooo .-h r- if t-- r- in in co o o o if o in if r- cm — i in co cm co in if — i coocoor- r-- in cm r-- cm ^o co cm CM CM CM —i— i— i —i — ( — i —i —i— i— i — i — i — ( — (CM I in co co in o-h-hoo oojvovoin oooifo ooooo ooooo o cm co in r- cm o o coif^oo o>m^o>co o co o co in omooor- co co ^ cm vo cm o — < in co coo cocovo oo cm c^ ooooo ooooo ooooo — i — i O —i CM O O O O O — i o ifooifvo ojifocoo — i — i r- cm o -f co in if mj cm cm if co co coh if coo co cm in o it ooo —I— i— i —I— I — i ^h — i CM — I CM —i —I— i— I hhhCMCM hCMCMhCM CM CM ooooifin co r- co in o cm if vo r^ co f o h if >n o h cm co if inr-cooo hoj coo o r~ — i cm co to if if if ifininvOvo r^ r- r- t— r- cooooo ooooo oooo-n — i^h^h^h— i h cm cm CO (O CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO (O if f if If if z Mi 0) CO c C CD •H O 1 S h TJ M 0) 1 r— 1 (13 -t-> Q. ^ a) a x--' M-. CO en •H N J h (X) D to M ai x: +-> -o to CU CO »-h XI Q) .—1 M •H X (0 co X o M X a m 0) -p 6 >- C o to Q. •H 6 tu c c > -P h cu to c O ^H tt) 0) X XJ x <-> M 1 cu +J CO to CD C CO c CO M 1 H M c •H O N O 1 1 CO 3 to c o £ -H H .—1 >- CO > (H to to 0) 0) r— 1 x*i x to •p rH o 0) a> D c .* o-.h o co 6 to #>. a o OQ c o •H (0 -P >— 1 O to (0 > (H M^ > co Hh (0 c 0> -H c X 6 • H O (0 iD c CM o • •H 1 +* ^~ CM o*> vO 10 O M • 4h 1 CD • CO --H O 00 Q. C cm »* co ^ co h w ^i co in no ^f >} n ^ now h ^ co oocoo^ cm -h co cm o co ^ co in o .— I r— 1 r-H r— I r-H r— I »-H f— I i-H rH r— I CM CM O if in CO HhiOCMO vO CM CO vO rH cooooocooo r-r-r^r--r- r~- co r~ r- r- I CM [-~ if if LO ^ t— rH CM CM I I I rH I I CO(M H CO rH ^o CM H CMH I n I CM CO I if CO CO 4 CO Ol I I I COn if) M' in in >n o or~voor~ o— i^-ooco HCOCM CO CO r-iH HCOCO r~ 1 CM CM CM CM H CO CO CM in CM O CM t^- CO CO CO o t ^ CM H H H H rH f— If— 1 rH p— 1 r— 1 r— Ir-H rH I vo CO CO it in CO co h vO OCO 'f co vO r- CO CO CO rH r- CM CM CM hh I HCN i oo in md in <} covo cm ^t in ^ if h 't oinr-r-co o if r~ co co h co co coin in --• in oo vo CM CM rH --H if CM if CM CO CM CM CM CM O CM vO CM CO m oo if vo cm co in h \o ^ o o r- o if rH CM CM rH CM CM CM CM — i CM vocooocor-i r~-\Oincovo nn h^o h CMCOCMCOCO <3-CMCMCMCM rH^H^H--iCM ■tco^oo ooor^inco •* m- in r- co hiahoo "j h r- o co cm co co in O r- r- in co h vOvOvococm ifr----Hr-vo co in h if co ocooiOh voor-^-o nn ^ cm ^ cocmcoooco vooovo^ --HOOOO 000--H--H OOOOO 000.-HO OOOOO O^h^hOO ^O H CO rH >f ^H CM —I < m H HCM CO CO (OOOOO "tvO vO>0 »o XX X r-or~inr- covocovocm O Q UJ rococoo-H cMifinvor- 000--1CM cMr-r~-t~-r- \0 vO \0 *0 ^O vO^OvOvOvD oor-vOMD ininco^oo ^rcMor-r-- ,-h ^, ^ ^ ^ CMCMCMCMCM oooor-^oj r-oooo'-H invot—ooo r-t--cooooo cocooooo ooooo vO^O^OvOvO vOvOvOvO^O t t — [ — l^ — [ — GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 31 cm h cm cm ^foci n h row ^r <3- cm vo co ^o r-M»o>h co in co co vo co o r- co oo ^ t n (\i co in co r- r^ r~- ^} cm h o^ o t in \0 in in vo co o h o r- cocNi [^ ^ o vo vO n H !-■ hOiIHO iOhO COCO vO CO CO (> h vO vO h CO P) h ^ COO CM r-cocovOt-- r- vO r- r~ r-- r- oo r- r~- r- r^ oo vo vo vo v£> r-- vo vO r- r- r- r- r- r- r-c-r^cor~ I — < I H H I (MhCI I I I ^(M I CM CM vO CM CO CM H I I CM CM I ^ CM I I ^" CM CM-f- iO HCMC>CO H CO CO vO -tf OCM H CO CO H hCMOI 00 H I h "3- CO I I CM I H I C0COCM I r^or-ocn cmvo hcoo o ovO\o t 'T co in \o vo vo in in r- in ^ o h in ^i- h hcmmido CMC- vono cm \o oo in in r- oo in in r- h co co o o cocm hcoo> h CM CM CM CM CM h hh CM CM CM h CM CO CO CM h h h hhh COCM CO CM CM H CM CM^h^h^h^ ■si- r-- cm h o ^ co^o cm oo co r- cm oo coo^tvoo in coin ho ^ ^rr~ coh ocoovovo ,— | H H ■— I H rHi-H^H^Hi— I H H H CM H •— ( ■— I ■— I i-H ■— I i— I H H M CM CM ■— I Hi— I H i-Hi— I h oo o h h hi hhh h^cmh (o cohcmcmh ihcocmcm cm cm co h h <^ m- co in in •^coin^H hcmhcmco i icohcm cm cm cm co i hhcohh cocMHHin cm cocm h in ■— I CM ■— < r-i r-< r—t ^-< HHHCNH ■— I H H H i— I i— I CM CM CM CM o 10 hcmcm in co in in in r- o h co m- r-oin-d-n vo cm »o ^f ^ r- md vo o r- oo o r- oo o CMCMCMhh h hh •— i h ■— i w— i h coco^-r~i-~ c» oocm m-coom-vo iT)Oo\"Jcm icmcmoh coinr-vOH -j^-hvo^ •^■ininoo in co h r- r-ooincoH cm h \o in •* in vo cm vo co cm co oo o cm cm cm cMOin OOOOO O hhO OOOOO OOOOO OOOOO OOOOO OhOOO inco-tf-tfco incMcot-~vo oo o in co vo cm inot- h co h t co o r- r- in r- r- o cm in cm CMCMCMhh hCOCMhh h CM h CM CM CM HHCM CMCMCMCMCM COCMhhh CMhhhh OhCMCO^ invOC^COvO f^ CO O H CM CO 'tf CM CO ^ in vO t~- 00 O O H CM CO ^f in O O h CM ^ih^-i-hh h h h h cm cm cm in in in in in vo^o^o vo vo vo md vo r- r- r- r- r- r^ r~ 00 oo oo t-- f- r- r~ r- r- r- r- c— r- r— r— r— r— t~- r» r- r» r- r- r- t-- r- r- r- r- r- r- r- r- r~ r-- r- c- r- 32 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 (0 M jC -p O CO (0 I •—I U TD M (0-— - i i— 1 03 H -P to a> q. o> c 2 Mi CO c i •-t 03 +> a ^ a> a. x-^ <+H CO en •H J N -P H (0 D Of CO H 0> X -p «o CO O) CO ^H OJ CO o c 1— 1 03 u 3 s H CD x o Q) X a h c +> e >. • H O 03 Q. 6 .»^V OJ >*-P 1 XI > c c c 03 0) H OJ OJ O o ■-* X h X X! a> -p a 1 OJ c^- •r-t +-> a> Q- o H UU T3 to D, 1 CO H -P C OJ OJ ro CJ C H (- u c •H O N (J l M 1 OJ 3 (0 c O S -H H i— 1 > co > H as co 0) a> ■-) x^i x 03 -p H o OJ 0) D C _* cT-H o a) £ (0 ^ a r-H o m c o •H CO -l-> ■—I O 03 03 >• H H ^ > 0) C|-l 03 C a> -h C X 6 • H o en c CM o • • H 1 -p OJ o^ vO 03 O fH • 4-1 1 6 OJ • to •-I o CO a c CO CM CM I CM CM CO CO CM r- r- r~- co in co in in j ^ inn in^inin a) h oo in in Lnvovo^j- hh(M HCN CM CM .-I CM co co t^ --< co <^ r- co co ■-H ■— I i— I CM CM r-H i— !•—<•— < co^TcncMvo co co in in .-I .-I \0 I CO H h\fl CO CO CM .-i CM v£> vO CM CM h CM CM CM CO CM CM CO CM CM HO ^ ^O CN vOCMOvO ^n .-I .—I .— i ^-| CM rH o in r- co cm moo "j OcninsOvo hoo^ hoooo oooo ^■vor~-cocM in^ooo HH H HOI CM .-) r- 1 H co - O) H. o 4-i a) XI • >- C|H x a X Q. >- X TS o O Q. 0) M M O T3 OQ PQ H 3 CQ .— 1 e e o o o 6 X H M o 0) CM 4-( H CM co n n • • • 03 C C m c c c 3 O O C • o o O • H • H O C • H -H •H H •P -P • H o -P +J -M OJ O o 4-> • H o o o +> 03 03 O -P 03 03 ro OJ H H 03 O (H H M. E H-i CM H 03 CM CM 4-. 03 CM M ■rH OJ OJ CM OJ 0) 0) T3 N N OJ N N N in o O CM o CM CM en o en vO en •—1 CM in i— i CM O CM C • • • r- • • • ro o o o • o o o x; o -p 1 1 1 1 1 1 M CM in o en f—t vO CM in o CM CO t CO O •—< CM in .—1 o o H 03 o o O o o o o o o c c c c c c c 1— 1 ro -p -p -p -p ■p -p ■p •rH c c c c c c c H 0) o> OJ 0) o> OJ OJ a> o o CJ o o o o +J H H H H M H H ro 01 0) OJ OJ o> OJ 0> S a Q. a. a. a. a. D, 9 X! o T3 ai CM en X GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 33 Table 3. - Clay Mineral and Carbonate X-Ray Analyses Sam- ple no. X-ray inten- sities (counts per sec. ) Cal- cite Dolo- mite Expand- Mixed- Vermiculite Mont- able lattice and moril- vermicu- clay vermiculite- Chloi lonite* lite minerals chlorite ite Kaolin- Illite ite 1 22 70 + 2 - - + 3 - - + 13 - - + 16 - - + 24 _ - + 26 18 42 + 57 - - +++ 60 - - +++ 61 - - +++ 94 16 75 + 97 20 80 + 98 - - + 113 23 42 ? 114 - - 119 45 80 + 120 22 55 + 123 35 55 ++ 124 - - ++ 125 25 38 + 126 16 80 131 35 85 132 - - +++ 138 55 100 ? 139 45 75 145 44 95 146 52 88 148 26 75 170 ? 55 171 13 30 172 25 80 173 20 60 ? 180 30 45 181 26 35 182 22 30 183 45 25 184 40 20 185 10 30 186 - - 188 - - 189 - _ ++ 190 - - ++ + ++ ? + ++ ? + ++ + ++ + ++ ? ++ + ++ + + ++ ? ++ + ++ ? ++ + ++ ++ + ? ++ + + ++ + ++ ++ + + ++ + + ++ + ? ++ + ? ++ + + ++ + + ++ ? + ++ + ? + ++ + ++ + + ++ ? + ++ ? + ++ ? + ++ ? + ++ + ++ ? + ++ + ++ + + +++ ++ + +++ ++ + +++ ++ + +++ ++ + +++ ++ + +++ ++ ++ +++ ++ +++ ++ ++ + + + + 34 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 Table 3. - Continued Sam- ple no. X-ray inten- sities (counts per sec. ) Cal- cite Dolo- mite Expand- Mont- able moril- vermicu- lonite* lite Mixed- Vermiculite lattice and clay vermiculite- Chlor- Kaolin- minerals chlorite ite Illite ite 191 - - + 192 - - + 195 35 135 + 196 55 95 + 197 40 105 + 198 20 120 199 - 155 200 - - 201 - - + 202 - - +++ 203 - - ++ 204 - - + 205 - - +++ 206 - - +++ 207 - - +++ 208 - - +++ 209 - - +++ 291 - - 292 - - +++ ++ 293 - - +++ 294 - - +++ 312 18 85 313 - 40 314 - - 315 - - ++ 316 - - ++ 317 - - ++ 318 - - ++ 320 - - +++ 327 - - 328 - - 329 - - ++ 330 - - +++ ++ 331 - - +++ ++ 334 - - ++ 335 45 100 + 336 - - + 337 - - ++ 338 - - ++ 339 - - ++ 340 - - + 344 15 45 345 - - 357 17 55 358 - - + 365 55 70 + 369 20 60 372 50 105 + ++ + ++ ++ ++ + ++ + + + + + + + + + +++ ++ +++ ++ +++ + +++ + +++ + + + + + + + ? + ? ++ ? ++ ? + ? ++ ? + ++ + ++ + ++ + + + + ++ ? +++ + ++ + ++ + ++ + ++ + + + + + +++ ++ ++ ++ ++ + + ++ + ++ + + +++ + +++ + +++ + ++ + ++ + ++ + +++ +++ +++ ++ ? ++ + +++ + GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 35 Table 3. - Continued Sam- ple no. X-ray inten- sities (counts per sec. ) Cal- cite Dolo- mite Expand- Mont- able moril- vermicu- lonite* lite Mixed- lattice clay minerals Vermiculite and vermiculite- chlorite Chlor- Kaolin- ite Illite ite 374 25 85 376 25 60 377 - - ? + 378 - - + + 384 45 105 + 390 15 75 391 40 75 394 45 85 395 - - + 400 40 80 + 401 - 240 + 402 - 195 ? + 403 35 140 + 404 40 100 405 - 195 + 407 15 215 + 408 35 140 ++ 409 ? 110 ++ 410 - - ++ 411 15 170 + 412 - 90 + 413 - - ++ 415 - 205 + 416 - - + 417 - - + 421 - 245 + 422 - - + 431 65 165 + 601 30 - +++ 602 15 - +++ 603A - - ++ 603B - - ++ 603C - - ++ 603D - - ++ 603E - - ++ 619 - 40 + + 621 - 10 + + 622 - - ++ + 674 - - + 675 - - + 676 - - + 677 - - + + 678 - - + 679 - - + 680 - - + 681 - - + 682 - - + 687 11 65 + +++ ++ ++ ++ + ++ + + + + ++ ? ++ + ++ + ++ + ++ + +++ +++ + +++ ? +++ + +++ ? ++ ++ ? + + ? ++ ? ++ + + ++ + ++ + ++ ? ++ ++ ++ ++ ++ ++ ++ + + ++ ? ++ ++ ++ ++ ++ + ++ + + + + ++ + ++ + ++ + + + + ++ + +++ + + +++ ++ ++ + ++ + + + ++ ++ + ++ + + + + + + + + ++ ? 36 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 Table 3. - Contini, ed X-ray inten- sities ( counts Expand- Mixed- Vermiculite Sam- per sec. ) Mont- moril- able vermicu- lattice clay and vermiculite- Chlor- ple Cal- Dolo- Kaolin- no. cite mite lonite* lite minerals chlorite ite Illite ite 688 _ _ + t+ ? 689 - - + ++ + 690 - - + ++ ? 691 - - ++ + + 705 18 140 + + ++ 706 - 25 + + ? ++ 707 - - + ? ++ 708 - - + ? ++ 709 - - + ++ 710 - - + ++ 711 - - + ++ 712 - - ? + ++ 713 13 195 ++ + ++ 714 - 90 + + + ++ 715 - 75 ++ + ++ 716 - - ++ ? ++ 717 - - ++ ? ++ 718 - - ++ ++ ? 726 25 65 + +++ + 727 - 60 + +++ + 728 - - + + + +++ + 750 25 75 + ++ ++ + 751 - - + +++ ++ 752 - - +++ + + + 753 - - +++ + + + 754 - - +++ + + + 762 25 115 + ++ 763 - 35 + ++ ++ 764 - - + ++ ++ 765 - - + ++ ++ 766 - - + ++ ++ 767 - - + +++ +++ + 768 - - + +++ +++ + 769 - - +++ + + + 770 - - +++ + + + 771 - - +++ + + + 772 - - +++ + + + 773 - - + + + + + + 774 - - ++ + + + + 775 - - + + + + + + 779 12 30 + ++ + 780 - 25 + + ++ + 781 - - + + +++ + 782 - - + + +++ + 783 - - ++ ++ +++ + 784 - - +++ + + 785 - - +++ + + 786 - - +++ + + GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 37 Table 3. - Continued X-ray : mten- sities ( counts Expand- Sam- per sec.) Mont- moril- able ple Cal- Dolo- vermicu no. cite mite lonite* lite 787 _ _ + + + 788 - - ++ + 789 - - +++ 791 - - 792 - - + Mixed- lattice clay minerals Vermiculite and vermiculite- chlorite Chlor- ite Kaolin- Illite ite * +++ designates a strong indication of the mineral in the x-ray pattern; ++ designates a moderate indication; + designates a weak indication; ? designates doubtful identification. Table 4. - Average Mineral Content of Winnebago and Illinoian Tills by Zones of Weathering Profile Heavy Minerals Pro file zone K- feld- spar Na-Ca feld- spar No. of samples Tour- maline 8. Horn- zircon Garnet Epidote blende Total f erro- magnesian minerals No. of samples Illinoian Till G 13 5 22 7 16 26 48 49 22 A 11 5 9 12 14 30 39 41 5 B 12 6 31 10 18 25 43 46 16 BG 14 7 6 5 18 27 46 49 6 CL 14 7 19 6 14 19 57 60 16 CC 12 8 25 6 14 17 52 57 24 Unoxi- 11 10 12 7 23 21 51 57 2 dized Winnebago Till G 18 8 4 11 18 28 40 44 4 A 12 5 2 8 11 20 52 56 2 B 16 6 7 5 15 19 55 60 8 CL 18 5 2 3 13 19 60 64 3 CC 17 6 6 3 12 18 62 66 8 Unoxi- 19 8 2 4 12 22 56 62 2 dized 38 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 295 Table 5. - Content of Coarse and Fine Clay in the Hippie School and Rochester Sections Sample no. Zone Percent total clay Percent <0.5 micron Percent <2,>0.5 micron 762 763 764 765 766 767 768 769 770 771 772 773 774 775 777 778 779 780 781 782 783 784 785 786 787 788 789 791 792 CC CC CL CL CL CL BG G G G G G G G CC CC CL CL CL BG G G G G G B B 14.8 10.0 15.5 11.3 11.2 10.8 20.2 16.3 18.0 15.5 29.0 21.0 25.6 19.1 34.0 27.6 34.7 28.4 37.2 30.8 37.4 31.0 39.7 33.8 40.3 34.7 31.4 26.1 11.4 7.5 26.1 16.2 26.6 15.3 28.6 17.6 33.3 22.9 31.8 20.5 30.0 20.9 29.7 22.6 37.0 34.8 36.6 28.8 38.8 32.9 42.4 36.9 41.2 36.9 32.2 25.9 39.5 34.2 4.8 4.2 0.4 3.9 2.5 8.0 6.5 6.4 6.3 6.4 6.4 5.9 5.6 5.3 3.9 9.9 11.3 11.0 10.4 11.3 9.1 7.1 2.2 7.8 5.9 5.5 4.3 6.3 5.3 Goldich, S. S., 1938, A study of rock-weathering: Jour. Geology, v. 46, p. 17- 58. GUMBOTIL, ACCRETION-GLEY, WEATHERING PROFILE 39 REFERENCES Allen, Victor T., 1959, Gumbotil and interglacial clays: Geol. Soc . Amer. Bull., v. 70, p. 1483-1486. Brophy, J. A., 1959, Heavy mineral ratios of Sangamon weathering profiles in Illinois: Illinois Geol . Survey Circ . 273, p. 1-22. Droste, John, and Thorin, J. C., 1958, Alteration of clay minerals in Illinoian till by weathering: Geol. Soc. Amer. Bull., v. 69, p. 61-68. Frye, J. C., and Willman, H B., 1960, Classification of the Wisconsinan Stage in the Lake Michigan glacial lobe: Illinois Geol. Survey Circ. 285, 16 p. Frye, J. C, Shaffer, P. R., Willman, H B., and Ekblaw, G. E., 1960, Accretion- gley and the gumbotil dilemma: Amer. Jour. Sci . , v. 258, p. 185-190. y Gravenor, C. P., 1954, Mineralogical and size analysis df weathering zones on Illinoian till in Indiana: Amer. Jour. Sci., v. 252, p. 159-171. Kay, G. F., 1916a, Gumbotil, a new name in Pleistocene geology: Science, n. ser., v. 44, p. 637-638. Kay, G. F., 1916b, Some features of the Kansan drift in southern Iowa (abst.): Geol. Soc. Amer. Bull., v. 27, p. 115-116. Kay, G. F., and Apfel, E. T., 1929, The pre-Illinoian Pleistocene geology of Iowa: Iowa Geol. Survey, v. 34, p. 1-262. Kay, G. F., and Pearce, J. N., 1920, The origin of gumbotil: Jour. Geology, v. 28, no. 2, p. 89-125. Krusekopf, H. H., 1948, Gumbotil — its formation and relation to overlying soils with clay pan subsoils: Soil Sci. Soc. Amer. Proc . , v. 12, p. 413-414. Leighton, M. M., and MacClintock, Paul, 1930, Weathered zones of the drift sheets of Illinois: Jour. Geology, v. 38, no. 1, p. 28-53. Ruhe, R. V., 1956, Geomorphic surfaces and the nature of soils: Soil Science, v. 82, no. 6, p. 441-455. Simonson, R.W., 1954, Identification and interpretation of buried soils: Amer. Jour. Sci., v. 252, p. 705-732. U. S. Department of Agriculture, 1951, Soil Survey Manual: U.S. Dept. Agr. Handbook No. 18, 503 p. (~) Willman, H. B., 1942, Feldspar in Illinois sands: Illinois Geol . Survey Rept. Inv. 79, 87 p. Illinois State Geological Survey Circular 295 39 p., 5 figs., 5 tables, 1960 £ CIRCULAR 295 ILLINOIS STATE GEOLOGICAL SURVEY URBANA ^^