C556 /vf.fiS: 
 
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 (Ui^^^\ 
 
 Quaternary Geology of the 
 Martinsville Alternative Site, 
 Clark County, Illinois 
 
 A proposed low level radioactive waste disposal site 
 
 J** 
 
 B. Brandon Curry, Kathy G. Troost, and Richard C. Berg s^ <r \> 
 
 M-08 
 N-13 CN-14 M-101 CLK-02-03 M-06 
 
 M-07 
 
 M-03 
 
 Circular 556 1994 
 
 Department of Energy and Natural Resources 
 ILLINOIS STATE GEOLOGICAL SURVEY 
 
3 3051 
 
 00003 
 
 LIBRARY. 
 
Quaternary Geology of the 
 Martinsville Alternative Site, 
 Clark County, Illinois 
 
 A proposed low level radioactive waste disposal site 
 
 B. Brandon Curry*, Kathy G. Troost**, and Richard C. Berg* 
 
 * Illinois State Geological Survey, 615 E. Peabody Dr., Champaign, IL 61820 
 ** Shannon and Wilson, Inc., 400 34th St., Suite 100, Seattle, WA 98103 ^nV 
 
 Circular 556 1994 
 
 ILLINOIS STATE GEOLOGICAL SURVEY 
 Morris W. Leighton, Chief 
 
 Natural Resources Building 
 615 East Peabody Drive 
 Champaign, Illinois 61820-6964 
 
Cover Cross section of the Martinsville Alternative Site shows the bedrock and glacial drift units. 
 Length of section is approximately 5,000 feet; vertical exaggeration is lOx. 
 
 Editor — E. A. Latimer 
 
 Graphic Artists — M. Knapp, P. Carrillo, S. Stecyk 
 
 Printed by authority of the State of Illinois/ 1994/ 1200 
 
 printed on recycled paper using soybean ink 
 
CONTENTS 
 
 ABSTRACT 1 
 
 EXECUTIVE SUMMARY 1 
 
 INTRODUCTION 2 
 
 Data Sources 2 
 
 Quality Assurance 6 
 
 Laboratory Methods 6 
 
 Interpretation of Laboratory Data 6 
 
 BEDROCK LITHOLOGY AND STRUCTURE 8 
 
 Carbondale Formation 8 
 
 Modesto Formation 8 
 
 Bond Formation 11 
 
 Bedrock Structure 11 
 
 BEDROCK TOPOGRAPHY AND DRIFT THICKNESS 1 1 
 
 LITHOSTRATIGRAPHY AND PEDOSTRATIGRAPHY OF QUATERNARY DEPOSITS 13 
 
 Previous Work 13 
 
 Banner Formation 13 
 
 Casey Till Member 13 
 
 Lierle Clay Member 18 
 
 Yarmouth Soil 18 
 
 Martinsville Sand 21 
 
 Petersburg Silt 21 
 
 Glasford Formation 27 
 
 Smithboro Till Member 27 
 
 Mulberry Grove Member 31 
 
 Pike Soil 43 
 
 Vandalia Till Member 43 
 
 Berry Clay Member 56 
 
 Pearl Formation 56 
 
 Sangamon Soil 56 
 
 Roxana Silt 62 
 
 Farmdale Soil 62 
 
 Wedron Formation, Fairgrange Till Member 62 
 
 Peoria Loess 62 
 
 Parkland Sand 63 
 
 Henry Formation 63 
 
 Cahokia Alluvium 63 
 
 Peyton Colluvium 63 
 
 Lacon Formation 63 
 
 Petrographic Characteristics of Sand Units 63 
 
 GEOCHRONOLOGY 66 
 
 QUATERNARY GEOLOGICAL HISTORY AND ENVIRONMENTS OF DEPOSITION 71 
 
 Pre-Illinoian 71 
 
 Early Illinoian Martinsville Sand and Petersburg Silt 71 
 
 Illinoian Glasford Formation — Environment of Deposition of Diamicton (Till) 71 
 
 Smithboro Till Member 72 
 
 Mulberry Grove Member 72 
 
 Uniform Diamicton Fades, Vandalia Till Member 72 
 
 Melange Fades, Vandalia Till Member 73 
 
 Late and Post-Illinoian Deposits, Weathering, and Development of Stream Network 73 
 
 SUMMARY AND CONCLUSIONS 80 
 
 ACKNOWLEDGMENTS 80 
 
 BIBLIOGRAPHY 81 
 
 APPENDIX 84 
 
TABLES 
 
 1 Quaternary lithostratigraphic units of north-central Clark County and the MAS 7-8 
 
 2 Comparison of stratigraphy used in this report and in the Battelle Memorial Institute and 
 
 Hanson Engineers, Inc. report 18 
 
 3 Comparison of textural and clay mineral attributes of three members of the Glasford Formation 41 
 
 4 Lithic composition of sand units 66 
 
 5 Amino acid measurements of gastropod shells 69 
 
 6 Radiocarbon ages from Cahokia Alluvium at the MAS 70 
 
 FIGURES 
 
 1 Location of study area, outcrops, and reconnaissance borings 3 
 
 2 Generalized topography, location of outcrops and test holes, and section lines at the MAS 4-5 
 
 3 Cross section A-A' 9 
 
 4 Structure contour map of the upper surface of the Danville No. 7 Coal bed 10 
 
 5 Bedrock topography of part of Clark County as mapped by Horberg 12 
 
 6 Reinterpretation of bedrock topography shown in figure 5 12 
 
 7 Bedrock topography beneath the MAS 14-15 
 
 8 Thickness of glacial drift at the MAS 16-17 
 
 9 Litho fades log and laboratory data from outcrop samples collected at CC-11 19 
 
 10 Lithofacies log and laboratory data from outcrop samples collected at CC-8 20 
 
 11 Cross section B-B' 22 
 
 12 Cross section C-C' 23 
 
 13 Cross section D-D' 24 
 
 14 Cross section E-E' 24-25 
 
 15 Cross section F-F' 26 
 
 16 Cross section G-G' 25 
 
 17 Thickness of the sand and gravel facies of the Martinsville sand 28-29 
 
 18 Lithofacies log and laboratory data from samples of core CLK-02-02 30 
 
 19 Thickness of the Smithboro Till Member 32-33 
 
 20 Ternary plots of textural and mineralogical data for the Smithboro Till Member 34 
 
 21 Ternary plots of textural and mineralogical data for diamicton units at the MAS 35 
 
 22 Lithofacies log and laboratory data from samples of core D-l 36-37 
 
 23 Lithofacies log and laboratory data from samples of core C-l 38-39 
 
 24 Lithofacies log and laboratory data from samples of core M-07 40 
 
 25 Lithofacies log and laboratory data from samples of core M-106 42 
 
 26 Thickness of the Mulberry Grove Member 44-45 
 
 27 Elevation of the lower surface of the Mulberry Grove Member 46-^47 
 
 28 Thickness of lithofacies of the Mulberry Grove Member 48-49 
 
 29 Histogram and box diagrams of values of Cu for glacigenic diamicton units at the MAS 50 
 
 30 Smoothed traces of X-ray diffractograms of oriented, ethylene glycol solvated samples of the 
 
 <2 urn fraction of units from boring M-104 51 
 
 31 Thickness of the uniform diamicton facies of the Vandalia Till Member 52-53 
 
 32 Thickness of the melange facies of the Vandalia Till Member 54-55 
 
 33 Sketches of outcrops CC-15 and CC-16 57 
 
 34 Discontinuities and lithostratigraphic contacts from the angled boring series M-101 58-59 
 
 35 Lithofacies log and laboratory data from outcrop samples collected at CC-16 60 
 
 36 Ternary plots of textural and mineralogical data for the surficial units at the MAS 61 
 
 37 Thickness of Cahokia Alluvium 64-65 
 
 38 Average lithic composition of sand units 67 
 
 39 Percentage of quartz vs. grain size or range of grain sizes per slide from petrographic studies 68 
 
 40 Estimation of unit ages based on data from outside the MAS 68 
 
 41 Plot of Aile/Ile in the total hydrolysate vs. Aile/Ile in the free hydrolysate of Stenotrema 70 
 
 42 Interpreted environment of deposition of the Mulberry Grove Member 74-75 
 
 43 Elevation of the lower surface of the Vandalia Till Member 76-77 
 
 44 Outcrop CC-16 and pebble macrofabrics from the melange facies of the Vandalia Till Member 78 
 
 45 Sediment types of the melange facies of the Vandalia Till Member at CC-16 79 
 
 46 Sand and gravel bodies in loam diamicton of the melange facies 79 
 
ABSTRACT 
 
 The Martinsville Alternative Site was intensely studied 
 as part of a characterization program to select a poten- 
 tial site for the disposal of low level radioactive waste 
 in Illinois. As much as 206 feet of Quaternary deposits, 
 mostly composed of glacigenic sediment of Illinoian 
 age, overlie Pennsylvanian bedrock at the Martinsville 
 site. Sedimentation was strongly affected by two bur- 
 ied valleys carved into the bedrock. The thickest 
 known occurrences of four lithostratigraphic units con- 
 stitute the bedrock valley sediment fill. 
 
 Unique features of the lithostratigraphic units are 
 shown in detailed isopach maps, cross sections, and 
 
 structure contour maps. For example, a cone-shaped 
 feature (apex down) composed of the uppermost till 
 unit (the Vandalia Till Member of the Glasford Forma- 
 tion) disrupts the continuity of several underlying 
 units. Also, the thickest and most continuous sand and 
 gravel units occur at the bottom and top of the sedi- 
 ment sequence that fills the bedrock valleys. The in- 
 tensely examined stratigraphic succession at this site 
 has strengthened our understanding of the regional 
 glacial stratigraphic framework in central Illinois for 
 use in future geological, engineering, and environ- 
 mental studies. 
 
 EXECUTIVE SUMMARY 
 
 The Martinsville Alternative Site (MAS) was proposed 
 by the State of Illinois for a low level radioactive waste 
 disposal facility. Located in east-central Illinois north of 
 the city of Martinsville, the MAS covers 1380 acres. To 
 characterize the site, geological and hydrological inves- 
 tigations were conducted by the primary contractors, 
 Battelle Memorial Institute and Hanson Engineers, Inc. 
 (1990 a, b, c), and by the Illinois State Geological Survey 
 (Curry et al. 1991a, b) and the Illinois State Water Sur- 
 vey (1990a, b). This report is a synthesis of the geologi- 
 cal investigations of the MAS; results of hydrological 
 investigations are discussed only to provide insights to 
 the geometry and continuity of geologic units. Investi- 
 gations of the MAS constitute the most comprehensive 
 geological study of Quaternary glacial sediments ever 
 conducted in this part of Illinois. The studies helped to 
 delineate the succession of lithostratigraphic units at 
 the MAS and to integrate the stratigraphy and deposi- 
 tional environments of geologic units into the broader 
 regional context. Interpretations of the geologic units at 
 the MAS strengthened our understanding of the glacial 
 stratigraphic framework for use in future geological, 
 engineering, and environmental studies in east-central 
 Illinois. 
 
 The Quaternary succession at the MAS includes 20 
 to 206 feet of Illinoian alluvium and glacigenic depos- 
 its. This sediment fills four bedrock valley segments 
 carved into the Pennsylvanian Modesto and Bond For- 
 mations. The Quaternary glacigenic sediments are cov- 
 ered by a thin mantle that is less than 14 feet thick and 
 composed of weathered Sangamonian sediment and 
 Wisconsinan loess and alluvium. 
 
 Important findings of this study are as follows: 
 (1) Each Quaternary lithostratigraphic unit at the 
 MAS may be differentiated by some combination of 
 stratigraphic position, particle-size distribution, sort- 
 ing coefficient, and semiquantitative mineralogy of the 
 <2 urn fraction. The interpretation of stratigraphically 
 complex or hydrogeologically critical zones required 
 evaluation of all characteristics listed above. Other help- 
 ful attributes for differentiating units included pedo- 
 logic features, moisture content, and Atterberg limits. 
 
 (2) The thickness and distribution of glacigenic and 
 preglacial Quaternary lithostratigraphic units at the 
 MAS are influenced by the buried bedrock topography. 
 The Martinsville bedrock valley extends beneath the 
 MAS and contains the thickest known occurrences of 
 Petersburg Silt (50.4 ft) and two members of the Glas- 
 ford Formation, Smithboro Till (90.4 ft) and Vandalia 
 Till (129.4 ft). The North Fork Embarras bedrock valley 
 contains the thickest known occurrence of the Mul- 
 berry Grove Member (58 ft) of the Glasford Formation. 
 
 (3) The network of Quaternary buried bedrock val- 
 leys incised in Pennsylvanian bedrock appears to have 
 been affected by superposition and piracy of valley 
 segments during pre-Illinoian glaciation. Because the 
 buried bedrock valleys appear to have had a south- 
 ward gradient during the earliest Illinoian, the Peters- 
 burg Silt probably was deposited in a slackwater lake 
 in response to aggradation in the ancestral Wabash and 
 lower Embarras Rivers. 
 
 (4) The thickest and most continuous Quaternary 
 sand and gravel units occur along the bedrock valleys, 
 especially the sand and gravel facies of the Martinsville 
 sand and Cahokia Alluvium, which were deposited 
 during nonglacial intervals. The Martinsville sand, the 
 lowest aquifer in the glacial drift succession, was de- 
 posited in the deepest portion of the bedrock valleys. 
 Along two significant buried bedrock valleys, the sand 
 and gravel facies of the Mulberry Grove Member is also 
 thick and continuous; however, at the MAS, the conti- 
 nuity is disrupted by the overlying Vandalia Till Mem- 
 ber. The sand and gravel facies of the Mulberry Grove 
 Member is thickest (as much as 58 ft) along the North 
 Fork Embarras bedrock valley, which generally under- 
 lies the present-day North Fork Embarras River valley 
 near Martinsville and the MAS. 
 
 (5) The lithologic succession beneath the modern 
 valley of the North Fork Embarras River generally in- 
 cludes two aquifers within 60 feet of the ground sur- 
 face. The two aquifers are the sand and gravel facies of 
 the Mulberry Grove Member and the Cahokia Allu- 
 vium. These units are separated by a thin layer (<15 ft) 
 of diamicton belonging to the Vandalia Till Member. 
 
(6) The Vandalia Till Member of the Glasford Forma- 
 tion is the most widespread and thickest deposit at the 
 MAS. Near the center of the MAS, the Vandalia is as 
 much as 129.4 feet thick where the lower surface of the 
 unit is shaped like an inverted cone. The Vandalia thins 
 
 to about 55 feet across a radial distance of about 1,000 
 feet from the inverted apex. The origin of this feature is 
 unknown, although it is likely related to subglacial 
 erosion along a preexisting channel. 
 
 INTRODUCTION 
 
 In 1988, the Illinois State Geological Survey (ISGS) and 
 Illinois State Water Survey (ISWS) participated in 
 detailed investigations to characterize the geology and 
 hydrology of a proposed area, known as the Martins- 
 ville Alternative Site (MAS), for disposal of low level 
 radioactive wastes. The detailed characterization of the 
 site was undertaken to provide knowledge about sub- 
 surface conditions and variability of the geologic mate- 
 rials for use in hydrologic flow modeling, design of 
 engineered structures, and overall suitability assess- 
 ment of the site. 
 
 The Illinois Department of Nuclear Safety (IDNS) 
 contracted with Battelle Memorial Institute, Columbus, 
 Ohio, and Hanson Engineers, Inc., Springfield, Illinois, 
 to conduct the site characterization studies. Hanson 
 Engineers, Inc. planned and implemented site charac- 
 terization activities at the MAS. The technical disci- 
 plines emphasized in the characterization were 
 geology, hydrology, and geotechnology. Specific inves- 
 tigations, tests, and analyses included geologic map- 
 ping; geological resource evaluation; geotechnical 
 analysis; geophysical surveys; drilling, sampling, and 
 logging of rock and sediment samples; surface eleva- 
 tion and surface water surveys; and flood hazard, land- 
 form stability, and seismicity analyses. 
 
 Hanson Engineers, Inc., subcontracted Shannon and 
 Wilson, Inc., Seattle, Washington, as the primary inves- 
 tigator for many elements of the technical program, 
 including geologic mapping and analysis of the stratig- 
 raphy and lithology, geomorphic stability, and seis- 
 micity. 
 
 The ISGS and the ISWS were initially contracted by 
 the IDNS and later by Battelle to (1) review the reports 
 prepared by the other contractors for scientific and 
 technical accuracy, (2) advise other contractors on site 
 characterization activities and adequacy of the data, (3) 
 examine and analyze geological and groundwater sam- 
 ples and other data in cooperation with the contractors, 
 and (4) prepare interpretative reports of the site geol- 
 ogy, including correlating the site geology to the 
 broader, regional framework. 
 
 Knowledge of physical properties, thickness, distri- 
 bution, genesis, and age of the geologic units was used 
 to develop the site-specific geologic framework needed 
 for groundwater and geochemical modeling of the 
 MAS (Beard et al. 1991). Beyond these purposes, inves- 
 tigations of the MAS also constituted the most compre- 
 hensive geological study of Quaternary sediments ever 
 conducted in this part of Illinois. The studies helped to 
 delineate the succession of lithostratigraphic units at 
 the MAS and to integrate the stratigraphy and deposi- 
 tional environments of geologic units into the broader 
 
 regional context. Interpretations of the geologic units at 
 the MAS have strengthened our understanding of the 
 regional glacial stratigraphic framework for use in fu- 
 ture geological, engineering, and environmental stud- 
 ies in east-central Illinois. 
 
 This report is a synthesis of the geological investiga- 
 tions of the MAS. Results of hydrological investigations 
 are discussed only to provide insights into the geome- 
 try and continuity of geologic units. Most figures in this 
 report are derived from ISGS contract reports (Curry et 
 al. 1991a, b); figures derived from the contractors' re- 
 port (Battelle Memorial Institute and Hanson Engi- 
 neers, Inc. 1990a) to the IDNS are duly noted. Other 
 information about the geology of the MAS was pre- 
 sented in Troost and Curry (1991) and Curry and 
 Troost (1991). 
 
 After completion of the various studies, and as this 
 report was being prepared, a special commission ap- 
 pointed by the governor of Illinois concluded that the 
 site was unsuitable for the safe disposal of low level 
 radioactive waste (Simon et al. 1992). 
 
 Data Sources 
 
 Three primary data sources were used to characterize 
 the regional and site geology of the Martinsville Alter- 
 native Site. Data are from 
 
 (1) five reconnaissance borings (CLK-01-02 and 
 CLK-03-01 in fig. 1 and CLK-02-01, CLK-02-02, and 
 CLK-02-03 in fig. 2), which provided split-spoon sam- 
 ples about 1.5 feet long. Collected at 5.0 foot intervals 
 (Battelle Memorial Institute and Hanson Engineers, 
 Inc. 1988), these samples were analyzed first to develop 
 the stratigraphic framework. 
 
 (2) 103 continuously sampled borings and ten un- 
 sampled borings, which provided rock and drift sam- 
 ples, lithologic and geophysical logs, and other data. 
 The borings were drilled at 80 locations, most of which 
 are shown in figure 2. Characterization data from 53 of 
 the borings were used in this study. 
 
 (3) 13 outcrops, including three previously de- 
 scribed by MacClintock (1929), and four outcrops and 
 one core previously described by Kettles (1980, Curry 
 etal. 1991a). 
 
 This database is not identical to that presented in 
 Battelle Memorial Institute and Hanson Engineers, 
 Inc. (1990a, c). Excluded from this database were data 
 from some borings drilled during late stages of site 
 characterization, and from borings that duplicate data 
 of adjacent borings. Data from beyond Battelle's study 
 area, as shown in figure 1, were included. Additional 
 borings were completed at the site as part of the 
 geotechnical design; however, data from these borings 
 
■Extent of late Wisconsinan glaciation 
 Shelbyville Moraine 
 
 borings or outcrops 
 
 study area of Battelle Memorial 
 
 Institute and Hanson Engineers (1990a, b) 
 
 Figure 1 Location of study area, outcrops, and reconnaissance borings. 
 
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were not incorporated into this report because of time 
 constraints. 
 
 Quality Assurance 
 
 The quality assurance guidelines of the Battelle Memo- 
 rial Institute (Hanson Engineers, Inc. 1989a, b) were 
 followed in gathering and preparing new data from all 
 borings except reconnaissance borings (CLK series). 
 Technical procedures used in this study included those 
 for core and outcrop descriptions, semiquantitative 
 mineralogical analysis of the <2 urn fraction of subsam- 
 ples of core, radiocarbon dating, and particle-size 
 analyses by hydrometer and wet sieving (ISGS 1989). 
 Hanson Engineers, Inc. generated other data, also sum- 
 marized in this report. These data include core and 
 outcrop descriptions, moisture content, particle-size 
 determinations by hydrometer and wet sieving, coeffi- 
 cient of uniformity, Atterberg limits (plastic limit, liq- 
 uid limit, and plasticity index), and petrographic 
 analysis of the fine grained sand fraction. Data in the 
 project technical database (Battelle Memorial Institute 
 and Hanson Engineers, Inc. 1990c) were collected and 
 prepared in accordance with Battelle's quality assur- 
 ance program (Hanson Engineers, Inc. 1989a, b). Dr. 
 William McCoy, University of Massachusetts at Am- 
 herst, provided 11 amino-acid racemization measure- 
 ments of gastropod shells to aid in regional 
 stratigraphic correlations. The amino acid analyses also 
 were not conducted under the quality assurance plan. 
 Data from all three sources are listed in Battelle Memo- 
 rial Institute and Hanson Engineers, Inc. (1990c) and in 
 Curry et al. (1991a, b). 
 
 Laboratory Methods 
 
 Particle-size distribution The percentage of gravel 
 (>2 mm) was calculated from the subsample. The 
 weight of the gravel fraction was removed when calcu- 
 lating the relative percentages of sand, silt, and clay in 
 the <2 mm fraction of subsamples. The categories of 
 particle-grain size of the <2mm fraction included sand, 
 2 mm to 0.063 mm; silt, 0.063 mm to 0.004 mm; and clay, 
 <0.004 mm. Hanson Engineers, Inc. determined most of 
 the particle-size distributions by sieve and hydrometer 
 analyses. The ISGS extrapolated particle-size data from 
 Hanson's grain-size curves, which were based on sieve 
 and hydrometer analyses, and determined additional 
 grain sizes by using a hydrometer or a SediGraph, 
 which is an automated X-ray absorption technique. The 
 SediGraph analysis provides a cumulative plot of 
 grain-size percentages for all particles <53 urn; distribu- 
 tions of coarser particle sizes were determined by wet 
 sieving. Class nomenclature for grain size, such as loam 
 and silt loam, follows that of the U.S. Department of 
 Agriculture (Buol et al. 1980). 
 
 Clay mineralogy The <2 urn (<.002mm) fractions of 
 approximately 1,500 samples from outcrops and cores 
 
 were semiquantitatively analyzed for clay mineralogy. 
 The procedure used is discussed in ISGS (1989). Other 
 selected clay mineral analyses, reported by Kettles 
 (1980) and listed in the appendix, were performed by 
 Dr. Herbert D. Glass, ISGS, who developed the techni- 
 cal procedure discussed in ISGS (1989), Hallberg et al. 
 (1978), and Wickham et al. (1988). 
 
 Sand petrography The lithologies of fine grained 
 sand particles from subsamples of various sand units 
 were determined by point counting. The samples were 
 prepared in a thin-section laboratory (Thresher and 
 Son, Inc., Madison, Wisconsin) that met Battelle's qual- 
 ity assurance guidelines. A split of each sample was 
 washed on a 38 urn sieve to remove silt and clay-sized 
 particles. Each sample was dried and placed into a mold 
 and mixed with epoxy. The resulting solid tab was 
 polished, mounted to a glass slide, and ground to a 
 standard thickness. During analyses under a petro- 
 graphic microscope, a 1 mm square grid was optically 
 overlain on the prepared slide. The lithology was iden- 
 tified for 300 grains that lay on or nearest to nodes on 
 the grid. Point counts were made on the basis of 12 
 categories of lithic fragments; general slide quality, 
 grain size, and sorting were also noted. 
 
 Interpretation of Laboratory Data 
 
 Geologic units (table 1) were characterized and differ- 
 entiated by visual description and stratigraphic posi- 
 tion, augmented by data from semiquantitative clay 
 mineralogical analyses, particle-size distribution, and 
 the coefficient of uniformity (appendix). Less useful 
 were data related to sample moisture, such as moisture 
 content and Atterberg limits. Nondiagnostic data, 
 which include the coefficient of curvature, liquidity 
 index, specific gravity, and porosity, are not listed in 
 the appendix of this report, but they are reported in 
 Battelle Memorial Institute and Hanson Engineers, Inc. 
 (1990c). 
 
 The coefficient of uniformity described in the Uni- 
 fied Soil Classification System (Hanson Engineers, Inc. 
 1989b) was useful in distinguishing till members in 
 stratigraphically complex areas at the MAS. The coeffi- 
 cient is calculated from 
 Cu = D60/D10 
 
 where Cu = coefficient of uniformity, 
 D60 and D10 = the nominal particle-size at the 60th and 
 10th percent values on a cumulative 
 curve of coarse to fine particles. 
 
 The coefficient of uniformity is a relative measure of 
 sorting and takes into account the distribution of frag- 
 ments that have diameters less than the inside diameter 
 of the sampler. The inside diameter is about 1.8 inches 
 for a split-spoon sampler and about 2.5 inches for a 
 CME continuous sampler. The larger the coefficient, 
 the more poorly sorted (or well graded) the grain-size 
 distribution of the sample. 
 
Table 1 Quaternary lithostratigraphic units of north-central Clark County and the MAS. 
 
 Unit (symbol) 
 
 Age 
 
 Pedostrati- 
 
 graphic Description (thickness, ft); color of fresh core or outcrop 
 
 unit* (Munsell notation); plasticity, moist consistence*** 
 
 Discontinuities 
 
 Lacon Formation (I) Holocene Modem 
 
 Peyton Colluvium (pey) Wisconsinan, Modem 
 Holocene 
 
 Cahokia Alluvium (c) Holocene, Modem 
 
 Wisconsinan 
 
 Parkland Sand (pks) Wisconsinan Modem 
 
 Peoria Loess (p) 
 
 Roxana Silt (r) 
 
 Pearl Formation (pe) 
 
 Wisconsinan Modem 
 
 Wisconsinan Farmdale 
 
 late lllinoian Sangamon 
 
 Loam diamicton, silt loam (variable); grayish brown (10YR 
 5/2), yellowish brown (10YR 5/4); plastic to slightly plastic, 
 friable 
 
 Silt loam, loam diamicton (variable); grayish brown (10YR 
 5/2), brownish yellow (10YR 6/6); slightly plastic, friable 
 
 Interbedded gravel, fine to medium sand and silt loam (0- 
 35); grayish brown (2.5Y 5/2), gray (N 4/0), yellowish 
 brown (10YR 5/4), dark gray (10YR 4/2); plastic to 
 nonplastic, loose to friable 
 
 Fine grained sand (0-7), clean to clayey; very pale brown 
 (10YR 7/3), light gray (N 6/0); slightly plastic, very friable 
 
 Silty clay, silty loam (0-7); light brownish gray (10YR 6/2), 
 very pale brown (10YR 7/3), dark grayish brown (10YR 
 4/2). light gray (2.5Y 7/2), black (10YR 2/1); plastic, friable 
 to firm 
 
 Loam (1-4); light pinkish gray (7.5YR 6/1) 
 (10YR 5/8), black (N 2/0); plastic, firm 
 
 yellowish brown 
 
 Gravelly sandy, clean to clayey, fine grained sand, silty 
 clay (0-13); as above and strong brown (7.5YR 4/6); 
 nonplastic to plastic, loose to firm 
 
 Pedogenic; roots, 
 burrows, peds, etc. 
 
 Pedogenic 
 
 Lithologic, 
 pedogenic 
 
 Pedogenic 
 Pedogenic 
 
 Pedogenic, in- 
 cluding krotovina, 
 large Mn nodules 
 and concretions 
 
 Lithologic 
 
 Berry Clay Member (peb) late lllinoian, Sangamon Silty clay loam, clay loam, loam diamicton (0-12); dark gray Pedogenic, in- 
 
 Glasford Formation 
 
 Sangamonian, 
 Wisconsinan 
 
 lllinoian, 
 late lllinoian, 
 Sangamonian 
 
 (2.5Y 4/1), gray (N 6/0), pinkish gray (7.5YR 6/2), grayish 
 brown (10YR 5/2), black (N 2/0); plastic, firm 
 
 Berry Clay Member (gb) As above 
 
 Vandalia Till Member lllinoian 
 
 melange facies 
 B-horizon of Sangamon 
 Soil (gv-mx) 
 
 C3-horizon of Sangamon 
 Soil (gv-mo) 
 
 unoxidized diamicton 
 (gv-m) 
 
 uniform diamicton 
 facies (gv-u) 
 
 Sangamon As above 
 
 Sangamon 
 
 Sangamon 
 
 Mulberry Grove Member 
 sand and gravel facies 
 (gm-z) 
 
 lllinoian 
 
 Pike 
 
 As above, (0-2); grayish brown (10YR 5/2), brownish 
 yellow (10YR 6/6), red (2.5YR 4/8), black (5YR 2.5/1); 
 plastic, firm 
 
 As above; calcareous except along discontinuities (0-10); 
 light yellowish brown (2.5Y 6/2). brown (10YR 5/3); slightly 
 plastic, firm to extremely firm 
 
 Chiefly loam diamicton with lenses of gravelly sand, sand 
 and silt (0-34); gray (N 5/0); slightly plastic, firm to 
 extremely firm 
 
 Loam diamicton, few sand and gravel lenses (0-129); gray 
 (N 5/0); slightly plastic, extremely firm 
 
 Sandy loam to sorted sand and gravel (0-31); gray (N 5/0), 
 olive gray (5Y 5/2); nonplastic, loose 
 
 eluding krotovina, 
 large Mn nodules 
 and concretions 
 
 Pedogenic as 
 above 
 
 Pedogenic; 
 subangular blocky 
 structure 
 
 As above, but 
 coarser structure 
 
 Lithologic, sand- 
 filled joints, healed 
 fractures, and 
 glacigenic faults 
 
 Lithologic dis- 
 continuities as 
 above, but less 
 frequent 
 
 Lithologic 
 
 diamicton facies (gm-d) 
 
 silt loam facies (gm-s) 
 
 Loam diamicton (<10); gray (N 5/0), greenish gray (5GY Lithologic 
 
 5/1; rare); slightly plastic, extremely firm 
 
 Silt loam, silt (0-10); olive gray (5Y 5/2), gray (N 5/0), dark Lithologic 
 grayish brown (2.5Y 4/2); slightly plastic to plastic, firm 
 
Table 1 continued 
 
 Unit (symbol) 
 
 Age 
 
 Pedostrati- 
 
 graphic Description (thickness, ft); color of fresh core or outcrop 
 
 unit* (Munsell notation); plasticity, moist consistence*" 
 
 Discontinuities 
 
 Smithboro Till Member 
 loam diamicton facies 
 
 (gs) 
 
 silt loam diamicton 
 facies (gs-s) 
 
 Petersburg Silt (ps) 
 
 Martinsville sand 
 silty clay facies (ms-s) 
 
 sand and gravel facies 
 (ms-z) 
 
 diamicton facies (ms-d) 
 
 Banner Formation 
 Lierle Clay Member (bl) 
 
 Casey till member 
 B-horizon of Yarmouth 
 Soil (bc-x) 
 
 C3-horizon of Yarmouth 
 Soil (bc-o) 
 
 unoxidized diamicton 
 (be) 
 
 Bond Formation (Pb) and 
 Modesto Formation (Pm) 
 
 lllinoian 
 
 lllinoian 
 
 early lllinoian 
 
 Pike (rare) Loam diamicton (0-44); gray (N 5/0); slightly plastic, firm 
 
 Silt loam diamicton (0-58); gray (N 5/0; 5Y 4/1), very dark 
 gray (10YR 3/1), dark grayish brown (2.5YR 4/2), dark 
 olive gray (5Y 3/2), pale olive (5Y 6/3); slightly plastic to 
 plastic, firm to extremely firm 
 
 Silt loam, silt, fine- to coarse-grained sand (0-50); pale 
 olive (5Y 6/3), dark olive gray (5Y 3/2), black (5Y 2.5/1); 
 nonplastic to slightly plastic, firm 
 
 Silty clay, clay loam (0-4); greenish gray (5GY 6/1), dark 
 greenish gray (7.5GY 4/1), dark grayish yellow (5Y 4/3), 
 red (10YR 4/6), black (N 2/0); plastic, firm to extremely firm 
 
 Sand and gravel (0-25); olive gray (5Y 5/2), grayish brown 
 (2.5Y 5/2); nonplastic, loose 
 
 Sandy loam diamicton (0-9); olive gray (5Y 4/2); plastic, 
 firm 
 
 Yarmouthian Yarmouth 
 
 pre-lllinoian 
 
 Silty clay, silty clay loam (0-8); gray (N 5/0), olive gray (5/Y 
 5/2), brown (10YR 5/3); plastic, firm 
 
 As above, but leached and with pedogenic features (0-5); 
 grayish brown (10YR 5/2), yellowish brown (10YR 5/6); 
 plastic, firm 
 
 Loam diamicton (0-5); light yellowish brown (10YR 6/4); 
 slightly plastic, extremely firm 
 
 Loam, clay loam diamicton (0-30); gray (N 4.5/0, 5Y 4.5/1); 
 slightly plastic, extremely firm 
 
 Pennsylvanian Yarmouth Sandstone, shale, siltstone, claystone, mudstone, 
 limestone, coal, conglomerate; variable; variable 
 
 Yarmouth 
 
 Yarmouth 
 
 Healed fractures, 
 sand-filled joints, 
 infrequent vertical 
 pedogenic cracks 
 
 Horizontal shear 
 planes separating 
 lithologic discon- 
 tinuities 
 
 Lithologic 
 
 Lithologic 
 
 Lithologic 
 
 Lithologic 
 
 Lithologic and 
 pedogenic 
 
 Pedogenic; sub- 
 angular blocky 
 structure 
 
 As above, but 
 coarser structure 
 
 Lithologic, including 
 sand-filled joints, 
 healed fractures 
 
 Lithologic, joints 
 
 •generally, but not necessarily associated with lithostratigraphic unit 
 
 "associated with no soil stratigraphic unit, but possesses leached, organic-rich horizons and fragments of wood 
 
 •"notation from Buol et al. 1980 
 
 BEDROCK LITHOLOGY AND STRUCTURE 
 
 The bedrock that immediately underlies the MAS is 
 composed of Pennsylvanian cyclothemic strata. Penn- 
 sylvanian rocks in Illinois are divided into three 
 groups: the McCormick, Kewanee, and McLeansboro 
 Groups, which are subdivided into seven formations 
 (Willman et al. 1975). Three of these formations were 
 encountered in boreholes at the MAS. From base to top, 
 the units include the Carbondale Formation of the Ke- 
 wanee Group and the Modesto and Bond Formations 
 of the McLeansboro Group (fig. 3). 
 
 Carbondale Formation 
 
 The Carbondale Formation, about 200 feet thick near 
 the MAS (Willman et al. 1975), is characterized in the 
 
 Illinois basin by minable coal beds. The uppermost 
 member of the Carbondale Formation, the Danville 
 (No. 7) Coal, is approximately 3.8 feet thick in borings 
 M-03 and M-04. This unit is a regionally significant 
 marker bed. The structure of its upper surface is de- 
 picted in figure 4. The underclay associated with the 
 Danville (No. 7) Coal is about 7.5 feet thick at the MAS 
 (Battelle Memorial Institute and Hanson Engineers, 
 Inc. 1990a). 
 
 Modesto Formation 
 
 The Modesto Formation generally is composed of a series 
 of partial cyclothemic sequences dominated by gray 
 shale and less sandstone, claystone, siltstone, limestone, 
 
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and coal. Regionally, the Modesto Formation is about 
 200 feet thick, but at the MAS, its maximum thickness 
 is 165 feet. The thickness of monolithologic beds within 
 the cyclothemic sequences varies from 1 inch to 60 feet. 
 Shale sequences, including claystone, siltstone, and mi- 
 nor mudstone, are typically about 20 feet thick, but they 
 range from 1 to 50 feet thick. Beneath the MAS, beds of 
 black, carbonaceous, fissile shale range from about 1 to 
 5 feet thick. Sandstone layers, 6 to 60 feet thick, occur as 
 sheet and channel deposits. 
 
 Members of the Modesto Formation at the MAS 
 include, from base to top, the West Franklin Limestone, 
 Chapel (No. 8) Coal, Inglefield Sandstone, Womac 
 Coal, and Macoupin Limestone (?). The West Franklin 
 is composed of light gray, nodular limestone about 6 
 feet thick. It is overlain by the Chapel (No. 8) Coal, 
 which is composed of an underclay 2.5 feet thick and a 
 fissile coal 0.2 feet thick. The West Franklin Limestone 
 and Chapel (No. 8) Coal are marker beds within the 
 Modesto Formation at the MAS. 
 
 Sandstone bodies in the Modesto Formation and the 
 overlying Bond Formation are commonly discontinu- 
 ous and vary significantly in thickness. These units 
 appear to have been deposited as widespread sheets 
 and channel sands. The channel sands range from 6 to 
 60 feet thick within a lateral distance of about 8,000 feet. 
 Sheet sands average 20 feet thick. Sandstones com- 
 monly are interbedded with siltstones and claystones, 
 and contain sedimentary features such as soft-sediment 
 deformation, crossbedding, and rip-up clasts. Basal in- 
 traformational conglomerates containing clasts of coal, 
 limestone, and shale occur locally in the sandstones. 
 
 A limestone or calcareous sandstone occurs at the 
 top of the Inglefield Sandstone. Where present, this 
 layer marks the top of the Modesto Formation at the 
 MAS. The layer probably correlates with the Macoupin 
 Limestone of the Modesto Formation, or less likely 
 with the Carthage Limestone (Shoal Creek Limestone) 
 of the overlying Bond Formation (Jacobson 1985). 
 
 Bond Formation 
 
 The bedrock unit most commonly present at the bed- 
 rock surface of the MAS is the Bond Formation. Region- 
 
 ally, the Bond Formation is characterized by about 300 
 feet of claystone, shale, limestone, and sandstone (Will- 
 man et al. 1975). Formal members of the Bond Forma- 
 tion in eastern Illinois include, from base to top, the 
 Carthage Limestone, Mt. Carmel Sandstone, Flannigan 
 Coal, Reel Limestone, and Livingston/Millersville 
 Limestone. At the MAS, the Bond Formation is the 
 uppermost Paleozoic unit. It is overlain unconformably 
 by Quaternary glacial deposits. The Bond Formation is 
 thickest, about 165 feet, on the east side of the MAS. It 
 is absent on the west side and along the walls and floors 
 of several bedrock valley segments beneath the MAS. 
 The upper and lower limestone members of the Bond 
 Formation are not present at the MAS; the Carthage 
 Limestone appears to have been truncated by the Mt. 
 Carmel Sandstone. Identification of the Mt. Carmel is 
 tenuous, however, because of the lack of a distinctive 
 lithology or succession of lithologies separating the Mt. 
 Carmel from the Inglefield Sandstone of the Modesto 
 Formation (fig. 3). 
 
 At the MAS, sandstone is the most common lithol- 
 ogy at the bedrock surface. The bedrock immediately 
 underlying the glacial deposit is commonly gleyed and 
 breaks easily along bedding planes in the uppermost 3 
 feet. The sandstone is generally partially cemented 
 with carbonate and contains abundant chlorite; there- 
 fore, the friable character is probably diagenetic and 
 not pedogenic. 
 
 Bedrock Structure 
 
 The MAS is located on the east flank of the Oakland 
 Anticline, a subsidiary fold of the La Salle Anticlinal 
 Belt (Treworgy 1981). The structure contour map of the 
 Danville (No. 7) Coal indicates that the associated 
 strata dip about 0.5° east or 50 feet per mile in the study 
 area (fig. 4). The direction and degree of flexure are 
 consistent with the regional structure (Battelle Memo- 
 rial Institute and Hanson Engineers, Inc. 1990a). Minor 
 flexures are present in the MAS area (fig. 4). Faults 
 were neither noted nor interpreted from any of the 
 cores recovered at the MAS. 
 
 BEDROCK TOPOGRAPHY AND DRIFT THICKNESS 
 
 Horberg (1950) mapped the topography of the bedrock 
 surface in Illinois, and Piskin and Bergstrom (1975) 
 mapped drift thickness. At the time of their mapping, 
 however, the number of reliable data points was lim- 
 ited in Clark County. Horberg showed a deep, buried 
 bedrock valley adjacent to the MAS (fig. 5) that nearly 
 coincides with the present-day North Fork Embarras 
 River valley. The buried bedrock valley, which begins 
 northwest of the MAS, is a tributary of a larger buried 
 valley system that extends south and east. Test drilling 
 for characterizing the MAS revealed, in addition to 
 Horberg's original valley, other deep bedrock valley 
 segments beneath and near the MAS. Figure 6 shows 
 
 the current interpretation of the regional bedrock 
 topography. 
 
 Thin drift (glacial and postglacial deposits and re- 
 lated materials) covers a bedrock-cored moraine east of 
 the MAS (fig. 1), as interpreted from surface topogra- 
 phy, distribution of bedrock outcrops (Horberg 1950, 
 Kettles 1980), and reconnaissance borings for this 
 study. This moraine locally coincides with the eastern 
 limit of the bedrock valley system that underlies the 
 MAS; older drift units occur east of the moraine (Curry 
 et al. 1989). 
 
 The buried valley segments are informally named 
 the North Fork Embarras bedrock valley, and the west- 
 ern, northern, and southern segments of the Martins- 
 
 11 
 
R14W 
 
 R13W 
 
 R14W 
 
 R13W 
 
 Figure 5 Bedrock topography of part of Clark County 
 as mapped by Horberg (1950). 
 
 ville bedrock valley (fig. 7). The North Fork Embarras 
 bedrock valley is generally parallel and nearly coinci- 
 dent with the modern valley of the North Fork Embar- 
 ras River as mapped by Horberg (1950). The western 
 and southern segments of the Martinsville buried bed- 
 rock valley join the North Fork Embarras bedrock val- 
 ley southwest of the MAS and in the northern part of 
 Martinsville, respectively (fig. 7). A persistent basal 
 alluvium containing clasts of extraregional lithologies 
 (Martinsville sand) occurs in all segments of the 
 Martinsville bedrock valley. This observation suggests 
 that the segments are connected. 
 
 The drainage network of the buried bedrock valleys 
 may be part of an anastomosing pattern (fig. 7). Anas- 
 tomosing or interconnecting valleys were mapped in 
 large bedrock valleys filled with glacial drift, such as 
 the Teays-Mahomet bedrock valley system (Kempton 
 et al. 1991), in smaller bedrock valley segments in Illi- 
 nois (Vaiden and Curry 1990), and elsewhere. Anasto- 
 mosing patterns are relatively common surficial 
 features along valleys that received discharge from gla- 
 cial meltwater or glacial lake outbursts, such as along 
 the Mississippi, Illinois, and Wabash River valleys 
 (Schumm and Brakenridge 1987). Such patterns result 
 from blockages (local damming), superposed stream 
 segments, and stream piracy. 
 
 Figure 6 Reinterpretation of bedrock topography 
 shown in figure 5 based on test drilling for the MAS and 
 reconnaissance borings. 
 
 The bedrock valley network at the MAS was devel- 
 oped during the pre-Illinoian. Although absent from 
 the MAS, pre-Illinoian glacigenic diamicton and sorted 
 sediments are distributed south, west, and east of the 
 study area (MacClintock 1929, Ford 1970, Johnson, 
 Gross, Moran 1971, Johnson et al. 1972, Kettles 1980/ 
 Curry et al. 1989, 1991a, b), indicating that the area had 
 been covered by pre-Illinoian ice. Subsequent Illinoian 
 glaciation further eroded bedrock on the valley flanks 
 and divides. 
 
 The thickest drift in the study area was measured in 
 boring M-106 (206 ft) in the northeast part of the MAS, 
 above the northern segment of the Martinsville bed- 
 rock valley. The thinnest drift (20 ft thick) was noted in 
 boring M-120 immediately northwest of the MAS in 
 the valley of Bluegrass Creek (fig. 8). Bedrock was 
 cored in 49 of the borings evaluated in this study. In 30 
 of these, 5 feet or more of bedrock was penetrated and 
 sampled. The oldest Quaternary deposits of alluvium 
 and colluvium are derived mostly from the local bed- 
 rock, making determination of the bedrock surface dif- 
 ficult in a few places. For the most part, however, 
 contacts between till units and bedrock are sharp, and 
 apparantly erosional. 
 
 12 
 
LITHOSTRATIGRAPHY AND PEDOSTRATIGRAPHY 
 OF QUATERNARY DEPOSITS 
 
 Physical characteristics, thickness, and distribution of 
 the Quaternary lithostrati graphic units are described in 
 this section. Pedostratigraphic units as they generally 
 occur within the lithostratigraphic framework are de- 
 scribed to maintain the overall continuity of this sec- 
 tion. Table 1 provides summary descriptions of the 
 stratigraphic units and derivative facies found in 
 north-central Clark County. 
 
 Previous Work 
 
 MacClintock (1929) described several sections east of 
 the study area along Big Creek and Mill Creek (fig. 1). 
 Although changes have occurred in stratigraphic no- 
 menclature (Jacobs and Lineback 1969, Willman and 
 Frye 1970), his descriptions and interpretations remain 
 valid. He found a thick, pre-Illinoian paleosol (the Yar- 
 mouth Soil) developed in wood-bearing till, which was 
 referred to as the Casey till member of the Banner 
 Formation by Ford (1970). MacClintock noted that the 
 top of the paleosol was commonly covered by a thin, 
 fossiliferous, silty unit (Petersburg Silt or the Smith- 
 boro Till Member of the Glasford Formation), which in 
 turn is overlain by the uppermost Illinoian unit of the 
 area, a loam till (Vandalia Till Member of the Glasford 
 Formation). The Sangamon Soil is developed in the 
 upper part of the Illinoian deposits. Wisconsinan loess 
 covers the Illinoian deposits in nearly all places, with 
 the exception of stream valleys. 
 
 As more of the central Illinois region was explored, 
 the geologic units were described and given informal 
 names (e.g., Jacobs and Lineback 1969, Ford 1970). Will- 
 man and Frye (1970) formalized the names and desig- 
 nated type sections; Johnson et al. (1972) and Follmer et 
 al. (1979) summarized regional relationships. Unpub- 
 lished theses provide additional stratigraphic and clay 
 mineralogical information on Illinoian and pre-Illi- 
 noian deposits in central Illinois (Kettles 1980, Hartline 
 1981, Fox 1987) and Holocene deposits elsewhere in the 
 state (Stanke 1988, Hajic 1990). These studies set the 
 regional framework for recognition of stratigraphic 
 units at the MAS. Recent reports by Battelle Memorial 
 Institute and Hanson Engineers, Inc. (1988, 1990a, b) 
 describe the geology of the MAS, independently of this 
 report. Battelle Memorial Institute and Hanson Engi- 
 neers, Inc. (1990a, b, c) give informal, site-specific, stra- 
 tigraphic names to several units. Their terminology is 
 compared with that of this report in table 2. 
 
 Banner Formation 
 
 The Banner Formation, the oldest known Quaternary 
 lithostratigraphic unit in Clark County, is less than 2 
 feet thick at the MAS, but it is more than 30 feet thick 
 elsewhere in the study area (fig. 1). As defined by 
 Willman and Frye (1970), the Banner Formation over- 
 lies the Afton Soil and underlies either Petersburg Silt 
 or the Glasford Formation. The stratigraphic position 
 of the Afton Soil at its type locality in Afton Junction, 
 
 Iowa, however, is controversial. The age of pre-Yar- 
 mouthian deposits, once called Nebraskan, Aftonian, 
 and Kansan, is now regarded in Iowa as pre-Illinoian 
 (Hallberg et al. 1980), an informal convention that was 
 also adopted in Illinois (Johnson 1986). The informal 
 unit known as the Casey till member of the Banner 
 Formation (described below) contains abundant wood 
 fragments, indicating that an earlier soil once covered 
 the area. Yarmouth Soil is developed in the upper part 
 of the Banner. 
 
 Casey Till Member 
 
 Ford (1970) informally described and named the Casey 
 till member of the Banner Formation, but Kettles (1980) 
 correlated the unit in Clark County with the Hillery Till 
 Member of the Banner Formation described near Dan- 
 ville, Illinois (Johnson et al. 1972). Because the regional 
 distribution of the Hillery Till Member is not well 
 known, Ford's local nomenclature was retained. 
 
 The Casey (be in table 1) is composed of gray loam 
 to clay loam diamicton that contains a mean grain-size 
 distribution of 38% sand, 38% silt, and 24% clay, and a 
 mean clay mineral composition of 8% expandables, 
 63% illite, and 29% kaolinite plus chlorite (appendix). 
 The particle-size distribution of the Casey is consistent 
 at any section, but it varies regionally (Kettles 1980). 
 The mineralogy of the fine sand fraction (0.25 to 0.125 
 mm) of pre-Illinoian tills in northern Clark County 
 indicates they were deposited by the Huron-Erie Lobe 
 of the Laurentide Ice Sheet (Fox 1987). Sediments de- 
 posited by the Huron-Erie Lobe are differentiated from 
 Lake Michigan Lobe deposits by a greater content of 
 magnetic minerals, plagioclase, and calcite (Johnson 
 1964, Fox 1987). 
 
 Where exposed, the Casey is commonly oxidized 
 (Kettles 1980; oxidized samples are denoted as bc-o in 
 figs. 9, 10). The oxidized diamicton generally is yel- 
 lowish brown to brown and contains irregularly ori- 
 ented fractures that have sand fillings as much as 0.25 
 inch thick. The oxidization is considered part of the CI, 
 C2, and/or C3 horizons of the Yarmouth Soil (soil 
 horizon designations after Follmer 1985). 
 
 Although not observed at the MAS, the Casey till has 
 been identified east and west of the MAS in outcrops 
 CC-8 and CC-11 near Mill Creek, and in CC-20 north 
 of Casey, Illinois. An accessible exposure of the Casey 
 till member in Clark County is along Mill Creek at 
 CC-11 (fig. 1) at or near location 7 of MacClintock 
 (1929), where the unit is at least 15 feet thick (fig. 9). At 
 CC-11, the upper 3 to 5 feet of the Casey is a leached, 
 reddish brown, clay loam diamicton that contains a 
 well developed, pedogenic subangular, blocky struc- 
 ture and abundant, continuous clay cutans (fig. 9). Be- 
 low the leached zone is about 5 feet of oxidized 
 diamicton that has numerous horizontal, platy joints 
 coated with sesquioxides, and at least 3 feet of unoxi- 
 dized, wood-bearing diamicton. MacClintock (1929) 
 
 13 
 
14 
 
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 00 
 
 4- 
 
 
 
 
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 e 
 
 r 
 
 CM 
 
 .2 
 
 75 
 
 > 
 
 75 
 
 c! 
 
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 0) 
 
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 a 
 
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 8 
 
 3 
 
 n 
 
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 15 
 
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 17 
 
Table 2 Comparison of stratigraphy used in this report and in the Battelle Memorial Institute and Hanson 
 Engineers, Inc. report (1990a). 
 
 Battelle (1990a) 
 
 This report 
 
 Cahokia Alluvium 
 
 Peyton Colluvium 
 
 Parkland Sand 
 
 Peoria Loess 
 
 not reported/not present at MAS 
 
 Roxana Silt 
 
 Berry Clay 
 
 Upper Sand 
 
 Glasford Formation 
 Vandalia Till Member 
 
 Fractured Vandalia Till 
 
 Vandalia Till 
 Vandalia Sand 
 
 Sand Facies 
 
 Smithboro Till - 
 Petersburg Silt 
 Basal Sand — 
 
 Pre-lllinoian Silt and Clay 
 
 not reported/not present at MAS 
 
 Cahokia Alluvium 
 
 Peyton Colluvium 
 
 Parkland Sand 
 
 Peoria Loess 
 
 Wedron Formation 
 
 sandy silt facies of Roxana Silt 
 
 Berry Clay Member of Pearl and Glasford Formations 
 
 Pearl Formation 
 
 Glasford Formation 
 
 Vandalia Till Member 
 — melange facies 
 
 uniform diamicton facies 
 
 Mulberry Grove Member 
 
 I silt facies, sand and gravel facies 
 
 I diamicton facies 
 
 Smithboro Till Member 
 
 I silt loam diamicton facies 
 
 I loam diamicton facies 
 
 Petersburg Silt 
 
 Martinsville sand 
 — sand and gravel facies 
 
 silty clay facies 
 
 diamicton facies 
 
 Banner Formation 
 Lierle Clay Member 
 
 Casey till member 
 
 described 20 feet of sand and gravel above bedrock and 
 below the diamicton, but it is not presently exposed at 
 the outcrop. MacClintock's location 7 is the only loca- 
 tion in Clark County where thick sand and gravel is 
 reported to be associated with the Casey till member. 
 
 Lierle Clay Member 
 
 Willman and Frye (1970) named and described the 
 Lierle Clay as a member of the Banner Formation in 
 west-central Illinois. The unit is composed of soft, 
 leached clay and silty clay diamicton that commonly 
 becomes finer upward (bl in figs. 9, 10). The mineral- 
 ogy, dominated by smectite, also contains interstrati- 
 fied clay minerals and no chlorite. The Lierle is 
 interpreted to have been deposited as pedogenically 
 altered colluvium, alluvium, or lacustrine sediment 
 (Willman et al. 1966, Willman and Frye 1970). 
 
 Lierle Clay, as much as 8.5 feet thick, occurs at CC-8 
 and CC-11 east of the MAS. The sequence is composed 
 of leached, dark gray, massive to crudely stratified, 
 silty clay (figs. 9, 10). The material has numerous joints 
 coated with sesquioxides, likely due to weathering at 
 
 the face of the outcrop. The clay mineralogy is domi- 
 nated by expandable clay minerals. 
 
 The Lierle Clay Member at the MAS was identified 
 in core from borings M-02, M-ll and M-105. In each 
 case, the Lierle is less than 2 feet thick, overlies bedrock, 
 and underlies the silt diamicton facies of the Smithboro 
 Till Member of the Glasford Formation. Thus, its strati- 
 graphic relationship with the Martinsville sand (de- 
 scribed below) is unknown. Battelle Memorial Institute 
 and Hanson Engineers, Inc. (1990a) include the Lierle 
 Clay as part of their Pre-lllinoian Silt and Clay unit 
 (table 2). 
 
 Yarmouth Soil 
 
 The Yarmouth Soil was named by Leverett (1898), who 
 described a buried soil from well cuttings at Yarmouth, 
 Iowa, near the maximum extent of Illinoian glacial de- 
 posits. The Yarmouth Soil in Clark County is devel- 
 oped in bedrock, Lierle Clay, or the upper part of the 
 Casey till member. 
 
 Pedogenic alteration of the Lierle Clay and the 
 Casey till member at CC-11 resulted in a leached zone 
 
 18 
 
soil depth particle-size distribution clay mineralogy 
 
 horizons (ft) (-2 mm) 
 
 50 100 50 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 Figure 9 Lithofacies log and laboratory data from outcrop samples collected at CC-11. 
 Location shown in figure 1. 
 
 19 
 
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 Location shown in figure 1. 
 
 20 
 
6 to 8 feet thick and an oxidized zone 5 feet thick (fig. 
 9). The upper Yarmouth (B horizon) at this site is red- 
 dish and has subangular, blocky structure and continu- 
 ous, thick, clay cutans. Diapiric intrusions of Lierle 
 Clay into the overlying Smithboro Till Member suggest 
 that the upper 3 feet of the Yarmouth Soil was affected 
 by soft sediment deformation, perhaps due to 
 glaciotectonic deformation or loading. Lierle Clay, cor- 
 responding to the Btg horizon of the Yarmouth Soil, 
 contains 34% to 48% clay compared with 19% clay in 
 the oxidized or unaltered Casey diamicton below. The 
 clay fraction contains abundant interstratified expand- 
 able clay minerals and no chlorite, and shows an up- 
 ward decrease of illite, all characteristics of material 
 that was weathered in an interglacial pedogenic envi- 
 ronment (Willman et al. 1966). 
 
 The lower Yarmouth (C horizon) is composed of 
 oxidized, sandy, and jointed material. The only clay- 
 mineral alteration is the transformation of chlorite to a 
 vermiculitic phase that partly expands in an atmos- 
 phere saturated with ethylene glycol (Willman et al. 
 1966). Whereas the contact between the B and C hori- 
 zons is gradational, the contact between the C horizon 
 and unaltered Casey diamicton (the C4 horizon of Foll- 
 mer 1985) is abrupt. 
 
 Martinsville Sand 
 
 The Martinsville sand is an informal lithostratigraphic 
 unit at the MAS that occurs above bedrock and below 
 either the Petersburg Silt or the Glasford Formation. 
 The unit also was identified in CLK-03-01 south of 
 Martinsville (fig. 1). Pedogenic features, described be- 
 low, suggest that the Martinsville sand is younger than 
 the Lierle Clay, although no contacts between the units 
 were observed. 
 
 The Martinsville sand has three distinct intercalated 
 facies that occur in varying stratigraphic order and 
 consist chiefly of thick and continuous sand and gravel, 
 less diamicton, and silty clay (ms-z, ms-d, and ms-s on 
 figs. 3, 11-16, especially fig. 12). Battelle Memorial In- 
 stitute and Hanson Engineers, Inc. (1990a,b,c) referred 
 to the sand and gravel facies as the Basal Sand (table 2) 
 and included the other two facies of the Martinsville 
 sand as part of their PreTllinoian Silt and Clay unit. 
 
 Sand and gravel facies The sand and gravel facies of 
 the Martinsville sand (ms-z in table 1) is as much as 30.8 
 feet thick at M-06 (fig. 17). The unit occurs persistently 
 in borings that penetrate glacial drift below an elevation 
 of 490 feet in the lowest portions of the buried bedrock 
 valleys. The sand and gravel facies may be continuous 
 along the Martinsville and North Fork Embarras bed- 
 rock valleys. A bed of mostly well sorted, fine grained 
 sand, about 3 feet thick and containing coniferous wood 
 fragments, occurs in boring CLK-02-<)2 (fig. 18). 
 
 Thin layers in the sand and gravel facies of the 
 Martinsville sand are cemented with sesquioxides. The 
 genesis of the cemented zones probably is related to the 
 reduction of iron and manganese that may have oc- 
 curred in wetland pedogenic or diagenetic environ- 
 
 ments. Negligible pedogenic structure and the pres- 
 ence of dolomite and chlorite favor a diagenetic origin. 
 Also supporting a diagenetic origin of these cements is 
 the relative abundance of reduced iron and manganese 
 species, dissolved carbon, and methane in groundwa- 
 ter from the Martinsville sand (Battelle Memorial Insti- 
 tute and Hanson Engineers, Inc. 1990b). A 3-day 
 aquifer test indicated hydrological continuity of the 
 sand and gravel facies of the Martinsville sand along 
 the northern segment of the Martinsville bedrock val- 
 ley (Battelle Memorial Institute and Hanson Engineers, 
 Inc. 1990b). The hydrological continuity of the Martins- 
 ville sand along and between the other segments of 
 bedrock valleys was not tested. 
 
 Diamicton facies The diamicton facies (ms-d), as 
 much as 9 feet thick at CLK-02-03, is the least common 
 facies of the Martinsville sand. A distinctive olive green 
 color (5Y 4/2, Munsell notation) and a mineralogy rich 
 in kaolinite plus chlorite differentiate this unit from 
 other diamicton units at the MAS; particle-size distri- 
 bution varies and is not diagnostic. 
 
 The facies is generally leached or slightly dolomitic. 
 The provenance of the coarse fragments is mostly local 
 bedrock, but pebbles composed of quartz, quartzite, 
 and polymineralogic lithologies with provenance from 
 the upper Great Lakes or Canadian Shield, suggest that 
 some of the material is reworked from pre-Illinoian 
 glacigenic sediment. 
 
 Silty clay facies The texture of the silty clay facies 
 (ms-s) ranges from loam to clay, but it is silty clay at 
 most places. Uncommon, thin interbeds of fine to me- 
 dium grained sand occur within the silty clay. The unit 
 is as much as 4 feet thick at boring CLK-03-01, but it is 
 generally thin or absent. In core, this facies has contrast- 
 ing colors, including mottles of greenish gray (5GY 6/1, 
 Munsell notation) and red (10R 4/6). Clay content, as 
 much as 76% (fig. 18), is the greatest measured for any 
 geologic unit described in this study. As with the 
 diamicton facies, the silty clay facies contains more 
 kaolinite plus chlorite relative to other units at the MAS 
 (appendix). The silty clay facies commonly overlies the 
 sand and gravel facies. 
 
 Petersburg Silt 
 
 Willman et al. (1963) described and named the Peters- 
 burg Silt (ps in table 1). At the MAS, it is composed of 
 brown, laminated (often rhythmically) or uniform, fos- 
 siliferous silt loam and less commonly, well sorted, 
 very fine to coarse grained sand. The Petersburg occurs 
 below an elevation of about 505 feet in the bedrock 
 valleys, where it is as much as 50.4 feet thick at M-125, 
 the thickest known occurrence of this unit in Illinois. 
 Mean thickness at the MAS is 5.7 feet. East and south of 
 the MAS, the Petersburg is generally absent or less than 
 about 2 feet thick, as at exposure CC-8 (ps in fig. 10). 
 The mean grain-size distribution is 11% sand, 67% silt, 
 and 22% clay (appendix). The semiquantitative minera- 
 logical analyses of the <2 urn fraction show that the 
 
 21 
 
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 22 
 
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 23 
 
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 bedrock 
 
 
 
 
 
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 — I — 
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 1 
 
 1000 ft 
 
 Figure 13 Cross section D-U. All borings extend to bedrock. 
 
 M-111 M-12 
 
 650 -, 
 
 M-128 
 
 M-126 
 
 North Fork 
 Interstate 70 fill Embarras 
 
 River 
 
 400 J 
 
 sand and gravel 
 silt 
 
 diamicton 
 silty clay 
 
 bedrock 
 
 Figure 14 Cross section E-E'. All borings extend to bedrock. 
 
 24 
 
400 
 
 vertical exaggeration 10x 
 
 sand and gravel j^=liJ| silty clay 
 
 ■:■:•:■>>: 
 
 son-. 
 
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 Figure 16 Cross section G-G'. All borings extend to bedrock. 
 
 E-1 
 
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 Kettering 
 
 Branch . North Fork 
 
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mean composition of the Petersburg is 19% ex- 
 pandables, 52% illite, and 29% kaolinite plus chlorite; 
 unoxidized samples are composed of about 12% ex- 
 pandables, 57% illite, and 31% kaolinite plus chlorite. 
 The unit contains abundant coniferous wood fragments 
 and a few gastropod shells, including Stenotrema, Hen- 
 dersonia, and Succinea (Barry Miller, Kent State Univer- 
 sity, personal communication 1989). Inclusions of the 
 Petersburg commonly occur in the silt loam diamicton 
 fades of the Smithboro Till Member of the Glasford 
 Formation. Pedogenic alteration of the Petersburg is 
 restricted to a few leached layers of peat that possess 
 silt coatings on platy peds, and abundant root traces. 
 Associated with these organic-bearing layers are bub- 
 ble impressions probably caused by methanogenesis. 
 
 Glasford Formation 
 
 The Glasford Formation, named and described by Will- 
 man and Frye (1970), has four members in north-cen- 
 tral Clark County. In ascending order, the members are 
 the Smithboro Till, Mulberry Grove, Vandalia Till and 
 Berry Clay. These units overlie the Banner Formation, 
 Martinsville sand, and Petersburg Silt, and underlie the 
 Pearl Formation, Peyton Colluvium, and Cahokia Allu- 
 vium. Jacobs and Lineback (1969) initially described 
 the glacigenic members of the Glasford Formation east 
 of the Illinois River near Vandalia, Illinois. In this re- 
 port, the Berry Clay, normally an upper member of the 
 Glasford Formation, includes soft, gleyed diamicton at 
 the top of the Pearl Formation. The Glasford is at least 
 180.4 feet thick at M-106 in the MAS buried valley; 
 about 30 feet is exposed in several outcrops adjacent to 
 and east of the study area. The Glasford is thinnest and 
 locally absent below modern valley floors, such as at 
 M-120 at the mouth of Bluegrass Creek (fig. 3). 
 
 Smithboro Till Member 
 
 At the MAS, the Smithboro Till Member of the Glasford 
 Formation is composed of silt loam to loam diamicton 
 and commonly contains wood fragments and sparse 
 gastropod shells, especially where the diamicton is 
 silty. The mineralogy of the fine grained sand fraction 
 indicates that the Smithboro Till Member was depos- 
 ited by the Lake Michigan Lobe of the Laurentide Ice 
 Sheet (Fox 1987). The Smithboro is not exposed at 
 ground surface at the MAS, but it is as much as 97 feet 
 thick in the Martinsville bedrock valley at boring M- 
 106 (fig. 19), the thickest occurrence yet described in 
 Illinois. Mean thickness of the Smithboro is 28 feet at 
 the MAS. Elsewhere in Illinois, the Smithboro is not 
 known to exceed a thickness of about 10 feet. The 
 Smithboro is composed chiefly of diamicton, but layers 
 of sand and gravel were encountered in several of the 
 67 borings that penetrated the Smithboro. The Smith- 
 boro truncates the Petersburg Silt and Martinsville 
 sand at several localities under the MAS (figs. 12, 15). 
 
 An arbitrary textural boundary differentiates two 
 diamicton facies of the Smithboro. Approximately 63% 
 of the Smithboro diamicton samples contains 25% or 
 
 less sand, and is assigned to the silt loam diamicton 
 facies. The remaining 37% of the samples contains 
 more than 25% sand, and is assigned to the loam 
 diamicton facies. The mean texture and standard de- 
 viation of the combined Smithboro diamicton facies is 
 23.1 ± 8.0% sand, 51.9 ± 9.8% silt, and 24.8 ± 5.9% clay; 
 clay mineralogy is 26.2 ± 9.7% expandables, 45.4 ± 7.3% 
 illite, and 28.3 ± 6.1% kaolinite plus chlorite (appendix). 
 Figure 20 shows the textural and clay mineralogical 
 variability of the two Smithboro facies. Figure 21 shows 
 composite plots for all diamictons at the MAS, and the 
 variability of the Smithboro compared with other units 
 at the MAS. By comparison, the Vandalia Till Member 
 has a relatively uniform texture and mineralogy. 
 
 The silt loam diamicton facies (gs-s in appendix) has 
 inclusions of abundant wood fragments, uniform and 
 laminated silt, and gleyed sandstone. Sparse gastropod 
 shells and folded beds and laminae of silt and silty clay 
 are present. Composition of the inclusions indicates 
 they are redeposited gleyed bedrock, Petersburg Silt, 
 and silty clay facies of the Martinsville sand. The silt 
 loam diamicton facies is as much as 58 feet thick at 
 boring M-03. The unit has a mean grain-size distribu- 
 tion of 18% sand, 57% silt, and 25% clay, and a mean 
 clay mineral composition of 29% expandables, 43% il- 
 lite, and 28% kaolinite plus chlorite (appendix). The silt 
 loam diamicton facies is commonly overlain by or in- 
 terbedded with the loam diamicton facies (gs in table 1, 
 appendix). 
 
 The loam diamicton facies is as much as 44 feet thick 
 at boring M-02. The unit has a mean grain-size distri- 
 bution of 31% sand, 44% silt, and 25% clay, and a mean 
 clay mineral composition of 23% expandables, 49% il- 
 lite, and 28% kaolinite plus chlorite (appendix). The 
 two facies of the Smithboro have markedly different 
 physical properties reflecting the difference in clay and 
 silt content. The mean moisture content, for example, is 
 17.3% for the silt loam diamicton facies and 13.1% for the 
 loam diamicton facies (Curry and Troost 1991). 
 
 Segments of the bedrock valleys are filled primarily 
 with one or the other facies of the Smithboro Till Mem- 
 ber. For example, loam diamicton is the dominant fa- 
 cies of the Smithboro in the southern segment of the 
 Martinsville bedrock valley (e.g., boring D-l, fig. 22), 
 but the silt loam facies is dominant in the North Fork 
 Embarras Bedrock Valley (figs. 14, 23). Because of simi- 
 lar lithologic characteristics, differentiating the Smith- 
 boro loam diamicton facies from the overlying 
 Vandalia Till Member is difficult without laboratory 
 data or the intervening Mulberry Grove Member. In 
 some bedrock valley segments, the grain-size distribu- 
 tion in some borings gradually coarsens upwards, as 
 shown by the data from CLK-02-02 (fig. 18). At other 
 locations, abrupt changes occur from one facies to an- 
 other, such as in the cores from borings M-07 (fig. 24) 
 and M-106 (fig. 25). The abrupt contacts are interpreted 
 to be shear planes caused by deformation and inclusion 
 of Petersburg Silt or the silt loam diamicton facies 
 within the loam diamicton facies of the Smithboro. 
 
 27 
 
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 Figure 18 Lithofacies log and laboratory data from samples of core CLK-02-02. 
 Location shown in figure 2. 
 
 30 
 
Kettles (1980) correlated units in the area with the 
 Smithboro and Fort Russell till members, which were 
 originally described in the East St. Louis area by McKay 
 (1979). The Smithboro and Fort Russell units have li- 
 thologic properties similar to those of the silt loam 
 diamicton and loam diamicton fades, respectively, de- 
 scribed above for the Smithboro (table 3). The grada- 
 tional physical properties and contacts between the 
 fades, and the repetition of fades in some borings (figs. 
 24, 25) indicate that the two fades probably are contem- 
 poraneous. The Fort Russell till member is, therefore, 
 not recognized at the MAS. Regionally, Kettle's Fort 
 Russell unit may correlate with the lower part of the 
 uniform diamicton fades of the Vandalia Till Member, 
 described below. Data in table 3 indicate that the silt 
 loam diamicton fades of the Smithboro at the MAS 
 contains about 10% less expandable clay minerals and 
 about 7% more silt than the Smithboro as described in 
 other studies. These differences likely reflect a larger 
 component of Petersburg Silt reworked within the 
 Smithboro at the MAS. 
 
 Mulberry Grove Member 
 
 The Mulberry Grove Silt Member was described by 
 Jacobs and Lineback (1969) and formally named and 
 assigned to the Glasford Formation by Willman and 
 Frye (1970). In the study area, the Mulberry Grove is as 
 much as 58 feet thick at boring C-l (fig. 26), and com- 
 prises three easily distinguishable fades composed of 
 sand and gravel, diamicton, and silt loam. Because the 
 sand and gravel fades is dominant at the MAS, silt is 
 dropped from the name in this report. Regional distri- 
 bution of the Mulberry Grove Member is not well 
 known; sediments equivalent to the sand and gravel 
 fades and the silt fades were described in the type area 
 near Vandalia, Illinois (Jacobs and Lineback 1969) and 
 in Coles County, Illinois (Johnson et al. 1972, Ford 1970). 
 Battelle Memorial Institute and Hanson Engineers, 
 Inc. (1990b) considered the Mulberry Grove to be a 
 moderate-yielding aquifer. An approximate north- 
 south regional flow pattern is indicated by hydrologi- 
 cal data. The City of Martinsville draws water from this 
 aquifer, as well as from shallower water-bearing units. 
 The munidpal wells are located southwest of the town 
 of Martinsville, which is adjacent to the North Fork 
 Embarras River valley (fig. 2). 
 
 The Mulberry Grove Member, as much as 31 feet 
 thick under the MAS, is thicker adjacent to the MAS in 
 the North Fork Embarras River valley at borings C-l 
 (58 ft), M-110 (32 ft), and M-lll (36 ft; fig. 26). In 
 general, the Mulberry Grove Member of this report 
 corresponds to the Sand Fades described by Battelle 
 Memorial Institute and Hanson Engineers, Inc. (1990a, 
 b, c; table 2). The Mulberry Grove, encountered in 62 of 
 the 76 borings that penetrated this stratigraphic inter- 
 val, averages 17.8 feet thick. 
 
 A persistent layer of the diamicton fades is sand- 
 wiched by the sand and gravel fades of the Mulberry 
 Grove along the North Fork Embarras River buried 
 valley (fig. 14, cross section E-E'). Differing geochemi- 
 
 cal and piezometric data from the sand and gravel 
 layers that overlie and underlie the diamicton (Battelle 
 Memorial Institute and Hanson Engineers, Inc. 1990b) 
 support the interpretation that the diamicton layer is 
 laterally continuous. These data indicate that ground- 
 water in the upper sand and gravel unit interacts with 
 groundwater in the Cahokia Alluvium, whereas 
 groundwater in the lower sand and gravel layer is 
 geochemically distinct and does not readily interact 
 with the Cahokia. The continuous diamicton and thick 
 sand and gravel layers occupy a paleochannel eroded 
 in the Smithboro Till Member along the North Fork 
 Embarras bedrock valley (fig. 27). The channel mor- 
 phology is evident in a segment of cross section C-C', 
 which is drawn perpendicular to the buried valley axis 
 through borings M-126, M-127, and M-110 (fig. 12). 
 Because of the general coincidence of the North Fork 
 Embarras River valley and its buried bedrock valley 
 counterpart, a thick sand and gravel fades likely occurs 
 in this channel along any cross-valley profile of the 
 modern North Fork Embarras River valley in the study 
 area. 
 
 Sand and gravel facies The sand and gravel fades 
 (gm-z in table 1) is composed of well sorted, fine to 
 coarse grained sand, and less sorted sand and gravel, 
 and sandy loam. The facies, as much as 35 feet thick 
 under the east half of the North Fork Embarras River 
 valley, is commonly interbedded with thin layers of 
 the diamicton facies (fig. 23). A thick sand and gravel 
 facies also occurs in the northeast part of the MAS 
 (fig. 28). 
 
 Diamicton facies The diamicton facies (gm-d) is 
 composed of beds of gray loam to clay loam diamicton 
 less than 12 feet thick. The diamicton facies generally is 
 interbedded with the sand and gravel facies or in con- 
 tart with the Smithboro Till Member. The mean clay 
 mineral composition of the diamicton facies is 12% 
 expandables, 60% illite, and 28% kaolinite plus chlorite, 
 which is nearly identical to the clay mineral composi- 
 tion of the overlying Vandalia Till Member (fig. 21). At 
 D-l, the diamicton facies is soft and gleyed, and is 
 interpreted as a Bg soil horizon of the Pike Soil, a 
 pedostratigraphic unit that has been described at sev- 
 eral localities in central Illinois (Johnson et al. 1972, Fox 
 1987). 
 
 Silt facies The silt facies of the Mulberry Grove 
 Member (gm-s) consists of silty sediment that is gray, 
 yellowish brown, or locally black, organic rich, and 
 leached or weakly calcareous. The clay mineralogy of 
 the silt facies is nearly identical to that of the underlying 
 Smithboro Till Member (e.g., fig. 24). Less common than 
 the organic rich silts are thin beds of gray, uniform 
 calcareous silt associated with the diamicton facies. The 
 clay mineralogy of these beds is nearly identical to the 
 clay mineralogy of the diamicton facies and the overly- 
 ing Vandalia Till Member. The silt facies, generally less 
 than 1 foot thick at the MAS, is as much as 10 feet thick 
 
 31 
 
32 
 
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 <u 
 
 Si 
 
 s 
 
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 — 
 
 33 
 
Smithboro Till Member; combined facies 
 loam diamicton facies 
 silt loam diamicton facies 
 
 100°/« 
 sand 
 
 100% 
 
 illite 
 
 100% 
 expandables 
 
 100% 
 kaolinite/chlorite 
 
 Figure 20 Ternary plots of textural and mineralogical data for the Smithboro Till Member. The envelopes 
 encompass values within 1 standard deviation of the mean (appendix). 
 
 34 
 
number 
 
 of 
 samples 
 
 606 
 93 
 
 513 
 35 
 364 
 134 
 230 
 
 100% 
 clay 
 
 VandaliaTill Member; combined facies 
 b melange facies 
 c uniform diamicton facies 
 d Mulberry Grove Member; diamicton facies 
 [/e^ SmithboroTill Member; combined facies 
 f loam diamicton facies 
 
 g silt loam diamicton facies 
 
 100% 
 sand 
 
 100% 
 silt 
 
 100% 
 
 illite 
 
 100% 
 expandables 
 
 100% 
 kaolinite/chlorite 
 
 Figure 21 Ternary plots of textural and mineralogical data for diamicton units at the MAS. The envelopes 
 encompass values within 1 standard deviation of the mean. 
 
 35 
 
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 clay mineralogy 
 
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 Figure 24 Lithofacies log and laboratory data from samples of core M-07. Location shown in figure 2. 
 
 40 
 
Table 3 Comparison of textural and clay mineral attributes of three members of the Glasford 
 Formation in central Illinois. 
 
 Unit 
 
 Author (year of study) 
 
 Percentage of the <2um 
 Sand Silt 
 
 fraction 
 Clay 
 
 Semiquantitative 
 clay mineral analyses 
 
 (No. of samples) 
 
 Exp* 
 
 Mite K/C" 
 
 Vandalia 
 
 
 
 
 
 
 Kettles (1980) 
 (199)*" 
 
 46 
 
 33 
 
 21 
 
 12 
 
 66 22 
 
 Hartline (1981) 
 (39) 
 
 45 
 
 35 
 
 20 
 
 16 
 
 65 19 
 
 Jacobs and Lineback (1969) 
 (10) 
 
 43 
 
 38 
 
 19 
 
 9 
 
 70 21 
 
 Lineback (1981) 
 (97) 
 
 42 
 
 35 
 
 23 
 
 9 
 
 70 21 
 
 This study: melange facies 
 (86) 
 
 45 
 
 33 
 
 22 
 
 12 
 
 60 28 
 
 uniform facies 
 (488) 
 
 43 
 
 35 
 
 22 
 
 12 
 
 58 30 
 
 Fort Russell 
 
 
 
 
 
 
 Kettles (1980) 
 (75) 
 
 35 
 
 41 
 
 24 
 
 23 
 
 57 20 
 
 Hartline (1981) 
 (18) 
 
 40 
 
 38 
 
 22 
 
 24 
 
 56 20 
 
 Lineback (1981) 
 (75) 
 
 32 
 
 42 
 
 26 
 
 24 
 
 54 22 
 
 Smithboro 
 
 
 
 
 
 
 This study: 
 
 Smithboro, loam diamicton 
 
 facies 
 
 (109) 
 
 32 
 
 45 
 
 23 
 
 26 
 
 47 27 
 
 Kettles (1980) 
 (24) 
 
 26 
 
 50 
 
 24 
 
 40 
 
 41 19 
 
 Hartline (1981) 
 (21) 
 
 23 
 
 49 
 
 28 
 
 45 
 
 37 18 
 
 « 
 
 Lineback (1981) 
 (71) 
 
 25 
 
 47 
 
 28 
 
 43 
 
 38 19 
 
 This study: 
 
 Smithboro, silt diamicton facies 
 
 (218) 
 
 18 
 
 57 
 
 25 
 
 30 
 
 42 27 
 
 Smithboro, composite (loam 
 diamicton and silt diamicton 
 combined) (327) 
 
 23 
 
 53 
 
 24 
 
 29 
 
 44 27 
 
 * Exp = expandable clay minerals; " K/C = kaolinite plus chlorite; *** composite of Kettle's Till 50W 
 and Till 50E 
 
 41 
 
depth particle-size distribution coefficient of uniformity 
 
 (ft) (<2 mm fraction) 
 
 50 100 100 200 
 
 clay mineralogy 
 
 
 § 
 
 Peo 
 "Roxi 
 
 na Loess p 
 
 
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 CO 
 
 Pes 
 
 Berry Clay peb 
 
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 Figure 25 Lithofacies log and laboratory data from samples of core M-106. Location shown in figure 2. 
 
 42 
 
at boring M-07, where it is composed of both leached 
 and calcareous intervals of organic-bearing silt that 
 contains abundant root traces (fig. 24). The weakly 
 developed soil profiles are tentatively correlated with 
 the Pike Soil. 
 
 Pike Soil 
 
 Willman and Frye (1970) named the Pike Soil in west- 
 ern Illinois for a strongly developed, weathering pro- 
 file in the Kellerville fill Member of the Glasford 
 Formation. Correlation of the Smithboro and Kel- 
 lerville Till Members (Lineback 1979b) indicates that 
 the paleosol developed in the Mulberry Grove Member 
 at the MAS is the Pike Soil. The Pike Soil in western 
 Illinois is of interglacial character (Lineback 1979b, 
 Johnson 1986), whereas the soil of the Pike in eastern 
 Illinois is of interstadial character (Johnson, Gross, 
 Moran 1971). The difference in the degree of weather- 
 ing suggests that the temporal correlation of the Smith- 
 boro and Kellerville Till Members may not be valid, but 
 current evidence supports the tentative stratigraphic 
 assignment of the Pike in eastern Illinois. 
 
 Vandalia Till Member 
 
 The Vandalia Till Member of the Glasford Formation, 
 the thickest and most widespread till unit in central 
 Illinois, has been mapped and described in several 
 reports (Johnson 1964, Jacobs and Lineback 1969, 
 Johnson et al. 1972, McKav 1979, Lineback 1979a, b, 
 Follmer et al. 1979, Kettles 1980, Hartline 1981, Follmer 
 1982, Fox 1987, Battelle Memorial Institute and Hanson 
 Engineers, Inc. 1990a, b). The Vandalia Till Member 
 consists of loam diamicton that regionally has a distinct 
 particle-size distribution and clay mineralogy (table 3). 
 In this study, the means and standard deviations of the 
 sand-silt-clay contents for Vandalia diamicton are 42.7 
 ± 5.4% sand, 34.8 ± 5.4% silt, and 22.3 ± 3.8% clay; the 
 means and standard deviations for clay minerals are 
 12.4 ± 4.5% expandables, 57.8 ± 4.8% illite, and 29.6 ± 
 3.4% kaolinite plus chlorite (appendix). The mineral- 
 ogy of the fine sand fraction indicates that the Vandalia 
 was deposited by the Lake Michigan Lobe of the 
 Laurentide Ice Sheet (Johnson 1964, Fox 1987). The 
 mean coefficient of uniformity of particle-size distribu- 
 tion for Vandalia Till at the MAS is much greater than 
 that of the underlying Smithboro (106 vs. 32, all facies 
 combined; fig. 29; appendix), a discrepancy indicating 
 that the Vandalia is less sorted than the Smithboro. The 
 texture and sorting coefficients of the lower 10 to 15 feet 
 of the Vandalia Till are, however, similar to the loam 
 diamicton facies of the Smithboro Till Member. Small 
 differences in clay mineralogy, outlined below, are use- 
 ful in differentiating between the Vandalia and Smith- 
 boro where the Mulberry Grove is thin or absent. The 
 following characteristics aid in differentiating Vandalia 
 and Smithboro diamictons in the contact zone. 
 
 (1) The lower Vandalia and the diamicton facies of 
 the Mulberry Grove commonly contain more illite than 
 the loam diamicton facies of the Smithboro (mean val- 
 ues of about 60% and 47%, respectively; fig. 21). 
 
 (2) The basal Vandalia diamicton and the diamicton 
 facies of the Mulberry Grove commonly have vermicu- 
 lite indices less than 0. The loam diamicton facies of the 
 Smithboro has values greater than 1. 
 
 (3) The Vandalia generally has coefficients of uni- 
 formity greater than 50; Smithboro has coefficients less 
 than 50 (fig. 29). 
 
 (4) X-ray diffractograms of unoxidized Vandalia 
 rarely have diffraction peaks discernible from back- 
 ground at the 5.1° 29 (17A) position, which results in no 
 measurement of the heterogeneous swelling index 
 (HSI; ISGS 1989). The opposite generally is the case 
 with the Smithboro, and the HSI is greater than or 
 equal to (fig. 30). 
 
 (5) The Vandalia generally contains more sand 
 (mean 42.7%) than the Smithboro (mean 23.1%; appen- 
 dix). 
 
 Two facies of the Vandalia Till Member are recog- 
 nized at the MAS: a lower, uniform diamicton facies 
 and an upper, melange facies. The diamicton of both 
 facies has similar texture and mineralogy (fig. 21). In 
 Battelle Memorial Institute and Hanson Engineers, Inc. 
 (1990a, b, c), the uniform diamicton facies is named the 
 Vandalia Till, and the melange facies is named the 
 Fractured Vandalia Till (table 2). In a few locations, the 
 melange facies occurs at or near the base of the uniform 
 diamicton facies (fig. 24). In such cases, the melange 
 facies correlates with the Vandalia Till of Battelle. 
 
 Uniform diamicton facies The uniform diamicton 
 facies (gv-u in table 1), as much as 129.4 feet thick at 
 boring M-112, is known to be absent only at the mouth 
 of Bluegrass Creek adjacent to the MAS (fig. 31). The 
 uniform diamicton facies elsewhere in the study area is 
 at least 40 feet thick beneath the uplands (e.g., fig. 3) and 
 generally less than 15 feet thick beneath the valley of the 
 North Fork Embarras River (fig. 14). The uniform 
 diamicton facies, composed of loam diamicton, is char- 
 acteristically massive; however, discontinuities are 
 spaced more than 3 feet apart (Battelle Memorial Insti- 
 tute and Hanson Engineers, Inc. 1990a). The types of 
 discontinuities include joints or fractures and lithologic 
 discontinuities between diamicton and granular mate- 
 rial. When partly dried, the core commonly breaks with 
 difficulty along nearly horizontal partings that com- 
 monly have a thin, discontinuous filling composed of 
 sand or silt. The uniform diamicton facies was not 
 observed in outcrops in the study area. 
 
 Sand and gravel layers, locally as much as 18.5 feet 
 thick at M-10, are present in the uniform diamicton 
 facies at the MAS. Limited information from borings 
 suggests that the sand and gravel occurs in channels, 
 but the width and length of the channels are unknown. 
 A sand and gravel deposit that appears to have limited 
 lateral continuity within the uniform diamicton facies 
 at the MAS is referred to as Vandalia Sand by Battelle 
 Memorial Institute and Hanson Engineers, Inc. (1990a, 
 b, c; table 2 in this report). The Vandalia Sand appears 
 to be, on the basis of head data from piezometers, 
 hydraulically discontinuous across the MAS. In parts 
 
 43 
 
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 uniform diamicton facies 
 
 combined facies 
 Mulberry Grove Member 
 
 diamicton facies 
 Smithboro Till Member 
 
 loam diamicton facies 
 
 silt loam diamicton facies 
 combined facies 
 * All diamictons; MAS 
 
 Figure 29 Histogram and box diagrams of values of the coefficient of uniformity (Cu) for glacigenic 
 diamicton units at the MAS. Within the boxes of the box diagrams, the range of values falls within 1 
 interquartile range about the median, which is shown as a line within the box. The lines extending from the 
 boxes (the "whiskers") are 1.5 times the value of the interquartile range beyond the range indicated by the 
 box; outside values (shown as asterisks) found beyond the "whiskers" are as much as 3.0 times the inter- 
 quartile range; extreme outside values (shown as open circles) are more than 3.0 times the interquartile 
 range (see Velleman and Hoaglin 1981). 
 
 50 
 
Berry Clay Member 
 8.7 ft depth 
 
 Vandalia Till Member 
 
 melange facies, oxidized 
 
 12.0 ft depth 
 
 Vandalia Till Member 
 
 uniform diamicton facies 
 
 66.7 ft depth 
 
 Smithboro Till Member 
 
 loam diamicton facies 
 
 86.3 ft depth 
 
 Smithboro Till Member 
 
 silt loam diamicton facies 
 
 109.5 ft depth 
 
 Martinsville sand 
 
 diamicton facies 
 
 183.5 ft depth 
 
 2°6 
 
 Figure 30 Smoothed traces of X-ray diffractograms of oriented, ethylene glycol solvated samples of the <2 urn 
 fraction of units from boring M-104. 
 
 DEC 1 3 1334 
 
 51 
 
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of the site, the Vandalia Sand has heads similar to those 
 of the Mulberry Grove; in other parts, head data are 
 similar to those of the surficial layers and the melange 
 facies. 
 
 Melange facies The melange facies (gv-m in table 1) 
 is composed predominantly of loam diamicton, but 
 numerous layers, lenses, and pods of sand and gravel, 
 and less commonly, well sorted, uniform silt also are 
 present. Contacts between sand and gravel bodies, 
 diamicton, and silt are sharp. The melange facies con- 
 tains at least one lithologic or structural discontinuity 
 per vertical or horizontal 3 feet of sediment. The 
 melange facies is more than 23 feet thick in an outcrop 
 (CC-16) adjacent to the MAS, and as much as 30.3 feet 
 thick beneath the MAS at boring M-104 (fig. 32). Below 
 the uplands, the melange facies is generally found at the 
 top of the Vandalia but, in rare instances, it occurs at 
 depth within the uniform diamicton facies (for exam- 
 ple, at a depth of 73-80 ft in boring M-07; fig. 24). The 
 facies generally is absent beneath the valley of the 
 North Fork Embarras River. 
 
 The melange facies contains numerous discontinui- 
 ties with variable orientation and habit, including li- 
 thologic discontinuities and fractures. At outcrop 
 CC-15, there are nearly vertical joints at least 10 feet 
 long and filled with sand. These joints have a maxi- 
 mum width of 1 inch and taper downward to a crack 
 with no sand filling (fig. 33a). At the same outcrop, 
 vertically oriented tabular beds of uniform silt are off- 
 set along glaciotectonic faults with about 2 feet of ap- 
 parent displacement. At outcrop CC-16, the grain of 
 the lithologic discontinuities is generally horizontal 
 with planar to wavy surfaces (fig. 33b). Observations of 
 outcrops and unoriented core from four clusters of 
 angled borings indicate that the discontinuities occur 
 in all dip orientations. The angled borings also indicate 
 that the contact between the uniform diamicton facies 
 and melange facies is abrupt. The cluster of angled 
 borings at M-101 illustrates the slope of the contact 
 surface. The slope is as much as 14° within a horizontal 
 distance of about 50 feet (fig. 34). 
 
 Observations of outcrops and core from vertical and 
 angled borings provide an indication of the variability 
 and complexity of the distribution of fractures and 
 sand lenses within the melange facies (figs. 33a, b, 34, 
 45, 46). Scattered sand lenses, ranging from less than 1 
 inch to as much as 10 feet thick, were observed in cores 
 and outcrops. The proportion of sand as lenses, bodies, 
 and fracture fillings in the melange facies ranges from 
 less than 1% to 70%, and averages 15%. 
 
 Berry Clay Member 
 
 The Berry Clay Member is composed of leached and 
 pedogenically modified loam to clay loam diamicton. 
 Beneath the upland surfaces at the MAS, the Berry 
 forms a continuous layer over the Vandalia Till Mem- 
 ber of the Glasford Formation and under the sandy silt 
 facies of the Roxana Silt. In this report, the Berry Clay 
 Member is included in the upper Pearl Formation (peb 
 
 in table 1) to emphasize the continuity of this mantle. 
 Average thickness of the Berry Clay is 5 feet; maximum 
 thickness is 13 feet. 
 
 The Berry Clay Member contains more expandable 
 clay minerals than underlying units (fig. 35, appendix), 
 although the lowermost portion commonly has a clay 
 mineral composition similar to that of oxidized Van- 
 dalia diamicton. Mean values for clay mineral content 
 are 59% expandables, 27% illite, and 14% kaolinite plus 
 chlorite. Where the Pearl sand is absent, the contact 
 between the Berry and the Vandalia generally is 
 abrupt, and pedogenically the contact is at the bound- 
 ary between the B and C horizons of the Sangamon Soil. 
 Visually, the Berry Clay can be difficult to differentiate 
 from the overlying Roxana Silt, which contains little or 
 no gravel and possesses finer pedogenic features than 
 the Berry. The contact between the Berry and the 
 Roxana generally is gradational across a 1 foot zone. 
 Although textural differences are useful for differenti- 
 ating the surficial upland units, clay mineralogy is not 
 a useful differentiating method (fig. 36). 
 
 Pearl Formation 
 
 The Pearl Formation discontinuously overlies the 
 melange facies of the Vandalia Till Member of the Glas- 
 ford Formation. The Berry Clay Member is the soft, 
 gleyed diamicton in the upper Pearl. Pearl sand, re- 
 ferred to as the Upper Sand by Battelle Memorial Insti- 
 tute and Hanson Engineers, Inc. (1990a; table 2 in this 
 report), was not observed in the sediment fill of pre- 
 sent-day valleys. The mean thickness of the Pearl at the 
 MAS is 1.9 feet; a maximum thickness of 12.9 feet oc- 
 curs in angled boring M-106W adjacent to boring M- 
 106 (Battelle Memorial Institute and Hanson Engineers, 
 Inc. 1990a). 
 
 The Pearl Formation is composed of stratified, 
 poorly sorted sand and gravel; well sorted, medium 
 grained sand; and uncommon, thin interbeds of silty 
 clay. Illuvial clay occurs in the upper portion of the 
 Pearl and is related to the Sangamon Soil. Its pedogenic 
 origin is indicated by an abundance of fine clay (<1 urn) 
 relative to coarser clay (1-4 urn; fig. 35). Pearl Forma- 
 tion particles commonly are stained and coated with 
 sesquioxides and clay that demarcate gamma horizons 
 (layers of translocated clay, organic matter, and sesqui- 
 oxides below primary and beta B horizons; Johnson 
 and Hansel 1989). Clay mineralogy of the Pearl Forma- 
 tion is similar to that of the uppermost weathered Van- 
 dalia diamicton. Mean clay mineral values are 37% 
 expandables, 48% illite, and 15% kaolinite plus chlorite 
 (appendix). The lower contact of the Pearl at outcrop 
 CC-16 is locally convoluted, above which are stratified 
 and undeformed beds of sand or silty clay, completely 
 stained black and red by sesquioxides. 
 
 Sangamon Soil 
 
 The B horizon of the Sangamon Soil commonly occurs 
 in the Berry Clay Member of the Glasford and Pearl 
 Formations and the upper 1 to 2 feet of the melange 
 facies of the Vandalia Till Member. The latter material 
 
 56 
 
feet 
 
 o 1 2 
 
 meters 
 
 meters 
 
 Figure 33 Sketches of outcrops CC-15 (a) and CC-16 (b) showing variable lithic discontinuities within the melange 
 the Vandalia Till Member (from Troost and Curry 1991). Locations shown in figure 2. 
 
 facies of 
 
 57 
 
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 Berry Clay 
 
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 Figure 36 Ternary plots of textural and mineralogical data for surficial units at the MAS, including the 
 Berry Clay Member, Roxana Silt, and Peoria Loess. The envelopes encompass values within 1 standard 
 deviation of the mean. 
 
 61 
 
(gv-mx in appendix) is dominated by (1) pedogenic 
 structures, such as blocky to granular peds that have 
 continuous clay skins (argillans), (2) reddish, 
 brownish, or greenish hue, (3) abundant, variably swel- 
 ling vermiculite and smectite (Curry 1989), and (4) rela- 
 tively abundant, fine clay (as expressed by relatively 
 large fine to coarse clay ratios (<1 urn to 1-4 urn; fig. 35). 
 In most cases at the MAS, the Berry Clay Member is 
 interpreted to be the Btg horizon of the Sangamon Soil 
 developed in Pearl Formation or the Vandalia Till 
 Member. 
 
 At greater depth in the C horizon, oxidized sediment 
 occurs with organo-sesquioxide coatings along the 
 faces of joints and fractures in diamicton, or as grain 
 coats within bodies of sand and gravel. Oxidized and 
 calcareous diamicton with relatively coarse, blocky 
 structure occurs in the upper part of the C horizon (the 
 C2 horizon of Follmer 1985). Oxidation of the diamic- 
 ton in the C2 horizon is indicated by lighter hues com- 
 pared with unoxidized diamicton (grayish brown, 
 10YR 5/2 compared with gray, N 5/0). It is also de- 
 tected in the clay mineralogical analyses of the <2 urn 
 fraction. The pedogenic transformation of chlorite to 
 vermiculite results in lower kaolinite plus chlorite val- 
 ues (mean values for gv-mo and gv-m are 15.6 and 
 28.1, respectively) and greater vermiculite indices 
 (mean values for gv-mo and gv-m are 11.4 and 5.7, 
 respectively). In the C3 horizon, the faces of disconti- 
 nuities are stained with sesquioxides, although the 
 diamicton between the discontinuities is unweathered. 
 Stains commonly occur in the upper parts of sand and 
 gravel bodies often sandwiched between unaltered 
 diamicton. The C3 horizon is as much as 20 feet thick at 
 the MAS, extending more than 40 feet below ground 
 surface. 
 
 Roxana Silt 
 
 Johnson et al. (1972) named the sandy silt facies of the 
 Roxana Silt to designate a zone composed of pedogeni- 
 cally mixed, weathered Illinoian and Sangamonian 
 sediment and Wisconsinan loess (Roxana Silt). The 
 sandy silt facies of the Roxana Silt near Casey, Illinois, 
 is described in detail by Follmer (1982). At the MAS, the 
 Roxana is composed of pedogenically modified, 
 leached loam, 1 to 8 feet thick. The loam contains abun- 
 dant nodules and ped coatings composed of organo- 
 sesquioxides. The mean thickness of the sandy silt 
 facies of the Roxana Silt in the region is about 1.3 feet 
 (Fehrenbacher et al. 1986); mean thickness at the MAS 
 is about 3.0 feet. 
 
 The Roxana Silt is differentiated from the Berry Clay 
 Member and Peoria Loess on the basis of particle-size 
 distribution, stratigraphic position, and the presence of 
 features characteristic of the Farmdale Soil. The Roxana 
 Silt at the MAS may be sandier than in other parts of 
 Illinois (Follmer 1982, Johnson et al. 1972) because of a 
 potential proximal source of eolian sediment derived 
 from the valley of the North Fork Embarras River. In 
 general, the Roxana differs from the underlying Berry 
 Clay Member by containing more than about 35% silt 
 
 and less than 2% gravel. Roxana Silt generally can be 
 distinguished from the overlying Peoria Loess by its 
 content of more than 15% sand (fig. 36); the Peoria also 
 contains little or no gravel. Clay mineralogy is not a 
 useful differentiating criterion because the Berry Clay 
 Member, Roxana Silt, and Peoria Loess at the MAS 
 contain abundant expandable clay minerals (59%, 68%, 
 and 53%, respectively; appendix; fig. 36). 
 
 The Roxana is distinguished most easily from other 
 units where sediments are thick, such as in loess along 
 the Illinois River valley. At the MAS, however, the 
 Roxana Silt generally is less than 3 feet thick, possesses 
 no primary loess character, and has physical properties 
 similar to those of the underlying Berry Clay Member. 
 Were it not for regional relationships, a tenable inter- 
 pretation at the MAS would be that only one Wisconsi- 
 nan loessial unit is present and its lower portion is 
 pedogenically mixed with the Berry Clay Member. 
 
 Farmdale Soil 
 
 The Farmdale Soil is developed in the top of the Roxana 
 Silt and possesses cumulic B, E, or A horizons above the 
 Sangamon Soil. Pedogenic characteristics of the 
 Farmdale at the MAS are similar to, but not as promi- 
 nent as those of the Sangamon Soil. Typically, angular 
 blocky structure is somewhat coarser and sesquioxide 
 concretions are finer in the Farmdale than in the San- 
 gamon. The Farmdale also is typically grayer than the 
 Sangamon. At the MAS, contact between the Farmdale 
 and the overlying modern soil generally is gradual. The 
 contact was determined on the basis of textural differ- 
 ences (discussed above) between the Roxana Silt and 
 Peoria Loess (figs. 35, 36). The Bt horizon of the modern 
 soil, developed in Peoria Loess, is generally above the 
 Farmdale Soil. 
 
 Wedron Formation, Fairgrange Till Member 
 
 The Fairgrange Till Member of the Wedron Formation, 
 although absent at the MAS, is present in the Shelby- 
 ville Moraine 8 miles northwest of the study area. The 
 moraine marks the maximum southward advance of 
 the late Wisconsinan Lake Michigan Lobe about 20,000 
 years ago (fig. 1). The Fairgrange Till Member is com- 
 posed chiefly of clay loam or loam diamicton and lesser 
 amounts of sand and gravel (Ford 1970). 
 
 Peoria Loess 
 
 The Peoria Loess, named by Frye and Leonard (1951), 
 is further discussed in McKay (1979) and Follmer 
 (1982). At the MAS, the Peoria Loess continuously 
 mantles the upland surface. The Peoria Loess generally 
 is less than 6 feet thick and its mean thickness is 2.8 feet. 
 The Peoria is composed of leached, pedogenically 
 modified silt loam, silty clay loam, and silty clay. A 
 sand content of less than 15% distinguishes it from the 
 underlying Roxana Silt (fig. 36). The mean texture of 
 the Peoria is about 5% sandier than the regional mean 
 (Fehrenbacher et al. 1986). This textural difference may 
 be explained by an admixture of silty loess and eolian 
 sand derived from the North Fork Embarras River val- 
 
 62 
 
ley. The modern soil developed in the Peoria Loess 
 imparts pedogenic features such as biopores (roots, 
 etc.)/ clay cutans, and subangular blocky structure. 
 
 Parkland Sand 
 
 The Parkland Sand, named and described by Willman 
 and Frye (1970), consists of predominantly fine to me- 
 dium grained sand. The Parkland Sand is as much as 5 
 feet thick at M-01, and only locally present along an 
 upland corridor about 0.5 mile wide east of the North 
 Fork Embarras River valley. Parkland Sand, probably 
 eolian in origin, was mapped on upland surfaces out- 
 side the MAS east of the North Fork Embarras River 
 (Lineback 1979a). 
 
 Henry Formation 
 
 Willman and Frye (1970) named and described the 
 Henry Formation. It consists of surficial sand and 
 gravel from late Wisconsinan glaciation and thus is 
 restricted to the North Fork Embarras River valley ad- 
 jacent to the MAS. A thick deposit of the Henry Forma- 
 tion occurs beyond the late Wisconsinan glacial margin 
 in the valleys of large streams and rivers. Several ter- 
 races adjacent to the Holocene floodplain are com- 
 posed of this deposit (Miller 1973, Hajic 1990). In the 
 valley of the North Fork Embarras River, the sand and 
 gravel facies of the Cahokia Alluvium (described be- 
 low) may locally correlate with the Henry Formation. 
 Radiocarbon ages (discussed below) indicate the sand 
 and gravel is at least in part Holocene. Henry Forma- 
 tion was mapped about 7 miles north along the head- 
 waters of the North Fork Embarras River (Lineback 
 1979a). 
 
 Cahokia Alluvium 
 
 Deposits in the Mississippi River valley near East St. 
 Louis, Illinois, were described and named Cahokia 
 Alluvium by Willman and Frye (1970). The character of 
 the Cahokia was studied in the lower Illinois River 
 valley (Hajic 1985, 1990) and along tributaries to the 
 Vermilion River near Danville, Illinois (Stanke 1988). In 
 the study area, Cahokia Alluvium occurs below wide 
 terraces along valleys 1 to 10 feet above the modern 
 stream beds, and in the channels of modern rivers and 
 streams (fig. 37). Well sorted, medium grained sand 
 constitutes the bed load of present-day streams at low 
 flow and forms a thin mantle above the terrace sedi- 
 ments adjacent to the modern stream channels. This 
 mantle was deposited during recent floods. Numerous 
 bars along the stream channels are composed of well 
 sorted sand or coarser rock fragments as much as 2 feet 
 across. 
 
 The Cahokia is subdivided into a lower sand and 
 gravel facies (c-z) and an upper silt loam facies (c-s). 
 The sand and gravel facies, composed of uniform to 
 stratified, coarse grained sediment, is as much as 34 feet 
 thick at M-127. The silt loam facies, as much as 14.6 feet 
 thick at H-l, is composed of pedogenically altered, 
 soft, leached, uniform to vaguely laminated silt loam in 
 the North Fork Embarras River valley. The silt loam 
 
 facies is sandier in the valleys of Bluegrass Creek and 
 Kettering Branch. The silt loam facies is interpreted to 
 have originated as overbank sediment and as tongues 
 of colluvium, especially adjacent to valley slopes. The 
 lower layer of the sand and gravel facies and the upper 
 layer of the silt loam facies of the Cahokia along the 
 North Fork Embarras River are remarkably continuous 
 (fig. 14). Radiocarbon ages from the Cahokia adjacent 
 to the MAS span from 320 to 23,700 yr B.P. (discussed 
 below). Portions of the unit may be as old as late 1111— 
 noian. 
 
 Peyton Colluvium 
 
 Deposits near Peoria, Illinois, were described and 
 named Peyton Colluvium by Willman and Frye (1970). 
 The unit comprises colluvial and alluvial fans associ- 
 ated with archaeological sites along the lower Illinois 
 River (Hajic 1985). In the study area, the Peyton Collu- 
 vium occurs primarily at the base of slopes between the 
 uplands and valleys of the North Fork Embarras River, 
 Bluegrass Creek, Kettering Branch, and their tributar- 
 ies adjacent to and on the MAS. The lithology of the 
 Peyton Colluvium is similar to the lithology of the 
 sediment from which the colluvium is derived. The 
 local thickness of the Peyton Colluvium changes sig- 
 nificantly as it is removed by stream erosion at the base 
 of slopes. 
 
 Lacon Formation 
 
 Willman and Frye (1970) named and described the 
 Lacon Formation. This surficial lithostratigraphic unit 
 is composed of sediment flow and landslide material. 
 Because of the genetic definition of the Lacon Forma- 
 tion, its regional composition varies. Adjacent to the 
 MAS, small earth slumps were noted along Bluegrass 
 Creek where the stream impinged on the valley wall. 
 The largest slump, noted in early spring 1989 at out- 
 crop CC-16, involved 5,000 cubic feet of debris com- 
 posed of reworked Vandalia Till and overlying upland 
 units. Much of the slump material was removed by 
 creek erosion later in the spring. 
 
 Petrographic Characteristics of Sand Units 
 
 The petrography of sand units, except Cahokia Allu- 
 vium at the MAS, was determined to aid in strati- 
 graphic discrimination and interpretation of 
 environments of deposition. Table 4 lists the lithologic 
 categories counted for each sample. In general, the 
 petrographic characteristics of the sand and gravel 
 facies of the Martinsville sand and Pearl Formation 
 were distinctive due to pedogenic or diagenetic grain 
 coatings. The sand and gravel facies of the Mulberry 
 Grove Member was not petrographically distinct from 
 sand and gravel bodies within the uniform diamicton 
 facies of the Vandalia Till Member. 
 
 Samples from the sand and gravel facies of the 
 Martinsville sand consist of lithic components similar 
 to the other units studied in detail and suggest similar 
 provenance (fig. 38). Unique attributes of this unit in- 
 clude brownish coatings on the grains and nodular 
 
 63 
 
64 
 
S E 
 
 
 S 
 
 2 £ 
 
 (J 0) 
 
 o 2 
 
 £S 
 
 
 
 \ | 
 
 • 
 
 V 
 
 S I 
 
 
 
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 6 
 
 o 
 
 vt 
 
 s 
 
 3> 
 
 65 
 
Table 4 Lithic composition of sand units as interpreted from point counts of petrographic slides (from Battelle Memorial 
 Institute and Hanson Engineers, Inc. 1990a). 
 
 
 
 
 Sand bodies 
 
 in the 
 
 
 
 
 
 
 
 
 uniform diamicton 
 
 Sand and gravel 
 
 Sand and 
 
 gravel 
 
 
 
 
 facies, Vandalia Till 
 
 facies, 
 
 Mulberry 
 
 facies, Martinsville 
 
 
 Pearl Formation 
 
 Membei 
 
 
 Grove Member 
 
 sand 
 
 
 
 
 Std. 
 
 
 Std. 
 
 
 Std. 
 
 
 Std. 
 
 
 Mean 
 
 Dev.* 
 
 Mean 
 
 Dev.* 
 
 Mean 
 
 Dev.* 
 
 Mean 
 
 Dev.* 
 
 
 (9 slides) 
 
 (14 slides) 
 
 (20 slides) 
 
 (15 slides) 
 
 Quartz 
 
 
 
 
 
 
 
 
 
 Single grain 
 
 64.1 
 
 9.4 
 
 51.1 
 
 9.9 
 
 35.8 
 
 22.3 
 
 37.9 
 
 15.5 
 
 Polycrystalline 
 
 5.2 
 
 2.6 
 
 4.4 
 
 1.9 
 
 3.8 
 
 2.4 
 
 6.4 
 
 2.8 
 
 Undulatory extinction 
 
 2.7 
 
 4.4 
 
 1.5 
 
 1.6 
 
 1.1 
 
 1.1 
 
 1.3 
 
 1.2 
 
 Feldspar 
 
 6.2 
 
 2.1 
 
 4.9 
 
 1.9 
 
 3.8 
 
 3.0 
 
 5.3 
 
 2.9 
 
 Limestone 
 
 
 
 
 
 
 
 
 
 Fine grained 
 
 1.6 
 
 2.2 
 
 5.4 
 
 1.5 
 
 9.0 
 
 5.8 
 
 5.2 
 
 3.7 
 
 Crystalline 
 
 5.7 
 
 5.9 
 
 16.7 
 
 5.8 
 
 19.3 
 
 8.8 
 
 11.9 
 
 9.3 
 
 Fossiliferous 
 
 0.1 
 
 0.3 
 
 0.6 
 
 1.0 
 
 1.1 
 
 1.6 
 
 1.5 
 
 3.3 
 
 Siliceous 
 
 0.2 
 
 0.4 
 
 4.3 
 
 4.6 
 
 9.4 
 
 5.7 
 
 3.7 
 
 3.6 
 
 Rock fragments 
 
 
 
 
 
 
 
 
 
 Metamorphic/lgneous 
 
 4.0 
 
 2.8 
 
 3.4 
 
 1.7 
 
 5.7 
 
 3.6 
 
 5.2 
 
 3.9 
 
 Sedimentary 
 
 7.2 
 
 5.2 
 
 7.6 
 
 3.2 
 
 11.3 
 
 6.5 
 
 19.8 
 
 8.8 
 
 Iron cemented aggregates 
 
 2.8 
 
 4.2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Opaques 
 
 0.1 
 
 0.3 
 
 0.1 
 
 0.3 
 
 0.3 
 
 0.4 
 
 1.3 
 
 2.0 
 
 TOTALS 
 
 
 
 
 
 
 
 
 
 Quartz 
 
 72.0 
 
 6.4 
 
 57.0 
 
 10.6 
 
 40.7 
 
 21.6 
 
 45.5 
 
 17.1 
 
 Limestone 
 
 7.6 
 
 7.9 
 
 27.0 
 
 8.6 
 
 38.7 
 
 16.3 
 
 22.3 
 
 17.2 
 
 Rock fragments 
 
 11.2 
 
 4.5 
 
 11.0 
 
 4.1 
 
 17.0 
 
 8.0 
 
 25.0 
 
 9.6 
 
 "Standard deviation 
 
 aggregate grains of calcareous concretions. Either at- 
 tribute may be of pedogenic or diagenetic origin, but 
 the paucity of pedogenic structures suggests the latter. 
 The average lithic composition of the sand and 
 gravel facies of the Mulberry Grove Member, and of the 
 sand bodies within the uniform diamicton facies of the 
 Vandalia Till Member is similar. The most useful pet- 
 rographic criterion for differentiating these units was 
 sorting of lithic type per grain-size category (fig. 39). 
 The mean value and standard deviation of quartz 
 grains found in the various categories of sand size is 
 57.0 ± 10.6% in sand bodies of the Vandalia, and 40.7 ± 
 21.6% in the sand and gravel facies of the Mulberry 
 
 Grove Member. The relatively poor sorting (i.e., greater 
 standard deviation) of the latter unit indicates that the 
 sand and gravel facies of the Mulberry Grove was 
 deposited under more variable conditions of stream 
 power and sediment load than the sand bodies in the 
 Vandalia Till. 
 
 Samples of the Pearl Formation contain heterolithic 
 grains of silt and fine grained sand cemented by 
 brownish black sesquioxides. The Pearl also contains 
 less limestone fragments than the other units exam- 
 ined. The microconglomerate and paucity of limestone 
 fragments may be attributed to pedogenesis associated 
 with the Sangamon Soil. 
 
 GEOCHRONOLOGY 
 
 The chronologic age of most lithostratigraphic units at 
 the MAS is not well understood from on-site determi- 
 nations. The age of some deposits was estimated by 
 correlation of these units with those in areas where the 
 chronology is better known (fig. 40). The confidence in 
 
 these estimates lessens with increasing age. Along the 
 Illinois River valley, Peoria Loess was deposited from 
 about 25,000 to 12,500 B.P. (McKay 1979) and Roxana 
 Silt, from about 50,000 to 30,000 B.P. (McKay 1979, 
 Curry and Follmer 1992). Three ages from the Berry 
 
 66 
 
7.1% 
 
 5.0% 
 
 25.0°/c 
 
 22.3% 
 
 MARTINSVILLE SAND 
 
 1 1 .0% 
 
 45.6% 
 
 27.0% 
 
 SAND BODIES WITHIN 
 VANDALIATILL 
 
 57.0% 
 
 6.4% 2.8% 
 
 7.6% 
 
 3.5% 
 
 72.0% 
 
 PEARL FORMATION 
 
 40.7% 
 
 MULBERRY GROVE MEMBER, 
 SAND AND GRAVEL FACES 
 
 Figure 38 Average lithic composition of sand units. 
 
 average composition 
 based on point count data 
 
 | iron cemented grains 
 
 | total quartz grains 
 
 E53 total limestone fragments 
 
 HI total rock fragments 
 
 | other grains 
 
 67 
 
100 
 
 80- 
 
 60 
 
 2 
 co 
 
 3 
 
 3 
 O 
 
 40- 
 
 20- 
 
 MULBERRY GROVE MEMBER, 
 SAND AND GRAVEL FACIES 
 
 total slides - 20 
 average % - 40.7 
 standard deviation - 21 .6 
 
 t 
 
 t 1 1 1 1 1 1 1 r 
 
 Si-vfSa vfSa fSa f-mSa mSa fSa-fGr m-cSa mSa-fGr cSa-fGr 
 
 grain size of particles 
 
 100 
 
 80- 
 
 £ 60 
 
 CO 
 
 fi 
 
 CO 
 
 er 40 
 
 3 
 
 o 
 
 20- 
 
 SAND BODIES WITHIN 
 VANDALIA TILL 
 
 total slides - 14 
 average % - 57.0 
 standard deviation - 10.6 
 
 i 1 1 1 1 1 1 1 r 
 
 Si-vfSa vfSa fSa f-mSa mSa fSa-fGr m-cSa mSa-fGr cSa-fGr 
 
 Figure 39 Percentage of quartz vs. grain size or range of grain sizes per slide from 
 petrographic studies. Grain size ranges are positioned on the scale according to the 
 mean particle size of each range. 
 
 grain size of particles 
 
 Si - silt 
 Sa - sand 
 Gr - gravel 
 
 vf - very fine 
 f - fine 
 m - medium 
 c - coarse 
 
 20 
 
 40 
 
 60 
 
 80 
 
 100 
 
 120- 
 
 140 
 
 160- 
 
 180 
 
 200 J 
 
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 *3 
 
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 en 
 
 
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 1 "-C 
 
 u 
 
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 1 
 1 
 
 CD 
 
 Unit 
 
 Peoria Loess 
 
 Roxana Silt 
 
 Berry Clay 
 
 Pearl Formation, 
 Glasford Formation, 
 Petersburg Silt 
 
 Banner Formation 
 
 Age(ka) 
 
 Reference 
 
 Basis of age/region or site 
 
 Peyton Colluvium not determined — 
 
 Cahokia Alluvium 23.7-0.3 this study 
 
 250-12.5 
 
 50.0-30.0 
 
 130-21 
 
 302-132 
 
 788-302 
 
 McKay 1979, Follmer 
 etal. 1979 
 
 McKay 1979, Curry and 
 Follmer 1992 
 
 Johnson, Glass et al. 
 1971 
 
 Blackwelletal. 1990 
 
 Richmond and Fullerton 
 1986 
 
 Richmond and Fullerton 
 1986 
 
 Richmond and Fullerton 
 1986 
 
 ,4 C ages on wood adjacent to 
 MAS(0.3and23.7ka) 
 
 14 C ages on wood , lower 
 Illinois River valley, 
 Athens Quarry 
 
 '"C ages on organic-rich 
 sediment, wood and snails, 
 lower Illinois River Valley, 
 Athens Quarry 
 
 14 C age on organic-rich clay, 
 Shelbyville (21 ka) 
 
 Electron-spin resonance age 
 on mastodon molar, Hop- 
 wood Farm (1 30-73 ka) 
 
 Orbitally tuned marine 
 records (132-70 ka) 
 
 Orbitally tuned marine 
 records 
 
 Orbitally tuned marine 
 record, Matuyama-Bruhnes 
 magnetochron (~ 788 ka) 
 
 Figure 40 Estimation of unit ages based on data from outside the MAS. 
 
 68 
 
Table 5 Amino acid measurements of gastropod shells (from William McCoy, University of Massachusetts, 
 Amherst, personal communication 1989). 
 
 Free Total 
 
 Analyses hydrolysate hydrolysate 
 
 4 0.35 ± 0.01 0.25 ± 0.01 
 
 Core or boring 
 (depth, ft) 
 
 Unit 
 
 Genus 
 
 Lab no 
 AGL- 
 
 M-07 
 (118.0) 
 
 Mulberry Grove, 
 silt facies 
 
 Succinea 
 
 1324 
 
 M-14 
 (113.5) 
 
 Smithboro Till Member, 
 
 silt loam diamicton 
 
 facies (inclusion of 
 
 Petersburg Silt) 
 
 Stenotrema 
 
 1325 
 
 M-14 
 (147.0) 
 
 Petersburg Silt 
 
 Pomatiopsis 
 
 1326 
 
 CC-11 
 
 Smithboro Till Member, 
 
 silt loam 
 
 diamicton facies 
 
 Hendersonia 
 
 1327 
 
 CC-11 
 
 Smithboro Till Member, 
 
 silt loam 
 
 diamicton facies 
 
 Stenotrema 
 
 1328 
 
 CC-11 
 
 Smithboro Till Member, 
 
 silt loam 
 
 diamicton facies 
 
 Anguispira 
 
 1329 
 
 0.27 
 
 0.30 
 
 0.30 
 
 0.31 
 
 0.15 
 
 0.19 
 
 0.17 
 
 0.19 
 
 0.13 
 
 Clay include ca. 130 to 73 ka (Blackwell et al. 1990), 
 41,770 ± 1100 yr B.P. (ISGS-684; Follmer 1983), and 
 21,400 ± 1000 yr B.P. (ISGS-46; Johnson, Glass et al. 
 1971). The older ages are considered to be more repre- 
 sentative of the regional age of the Berry Clay than the 
 age of 21,400 yr B.P., which may have been collected 
 from a younger stratigraphic unit (W. H. Johnson, Uni- 
 versity of Illinois, personal communication 1990). Rich- 
 mond and Fullerton (1986) estimated the age of 
 Illinoian deposits to be 300,000 to 130,000 yr B.P. by 
 extrapolating from orbitally tuned, oxygen isotope 
 deep-sea records. 
 
 The geochronology of sediments deposited during 
 the pre-Illinoian and Yarmouthian Ages are not well 
 known. Pre-Illinoian lacustrine sediments near Dan- 
 ville, Illinois, and in adjacent western Indiana have 
 normal and reversed paleomagnetic polarity (Johnson 
 1986). The last change from normal to reversed polarity 
 is the Matuyama-Brunhes magnetochron that occurred 
 about 788,000 years ago (Richmond and Fullerton 
 1986). If the Casey till member correlates with the 
 Hillery Till Member of the Banner Formation in the 
 Danville area, as suggested by Kettles (1980), it is less 
 than 788,000 years old. 
 
 Correlation of the Petersburg Silt with other early 
 Illinoian deposits is supported by measurements of 
 amino acid racemization of gastropod shells. The 
 amino acid racemization reaction used in this study 
 was the measurement of the relative amount of alloiso- 
 leucine (Aile) and isoleucine (He) (McCoy 1987). Shells 
 of living gastropods contain only isoleucine. Through 
 geologic time, isoleucine epimerizes to the dias- 
 tereomer alloisoleucine, and the ratio, expressed as 
 Aile/Ile, increases to an equilibrium value of 1.30 ± 
 
 0.05. Although the rate of this reaction is known, the 
 temperature history of the sample must be known 
 within 1% variance through time to calculate an age of 
 about 30% accuracy. The temperature history generally 
 cannot be assumed or measured with such precision 
 (McCoy 1987). Thus, determining ages using this tech- 
 nique at the MAS was not attempted. 
 
 If deposits in a geographic area have experienced 
 similar temperature histories, measurements of amino 
 acid racemization can be used for relative age correla- 
 tions. Typically, the data are presented as Aile/Ile in 
 the free and peptide-bound amino acids and in the total 
 amino acid hydrolysate (Clark et al. 1989), or as 
 Aile/Ile in the total hydrolysate relative to Aile/Ile in 
 the free hydrolysate. Six amino acid racemization 
 measurements were made on gastropods from core 
 collected at the MAS and from units in outcrop CC-11, 
 including Petersburg Silt, and the Smithboro Till Mem- 
 ber and Mulberry Grove Member of the Glasford For- 
 mation (table 5). The results indicate that these units 
 correlate with Illinoian deposits near the type sections 
 (Miller et al. 1988) and other sediments in western 
 Indiana (fig. 41; Miller et al. 1987). 
 
 Four radiocarbon ages were determined from wood 
 fragments and organic debris in Cahokia Alluvium 
 adjacent to the MAS (table 6). Two ages from sediment 
 in the valley of the North Fork Embarras are Holocene, 
 including an age of 8,370 ± 300 yr B.P. (ISGS-2176) from 
 small woody fragments and powdery organic-rich de- 
 bris found at the contact between the sand and gravel 
 facies and silt loam facies of the Cahokia Alluvium. A 
 fragment of hickory wood (L. R. Follmer, ISGS, per- 
 sonal communication 1990) in alluvium adjacent to the 
 North Fork Embarras River yielded an age of 320 ± 70 
 
 69 
 
Table 6 Radiocarbon ages from Cahokia Alluvium at the MAS. 
 
 Age 
 
 ISGS lab no. Material 
 
 Location 
 
 Depth (ft) 
 
 320±70 
 
 2073 
 
 wood (hickory) 
 
 CC-18, North Fork Embarras 
 River valley 
 
 4.5 
 
 8,370±300 
 
 2176 
 
 unidentified 
 wood fragments 
 
 H-1 , North Fork Embarras 
 River valley 
 
 14.2 
 
 14,4901140 
 
 2024 
 
 wood (spruce) 
 
 M-120, Bluegrass Creek valley 
 
 10.8-11.2 
 
 23,7201300 
 
 2113 
 
 wood fragments 
 plus organic-rich 
 clay 
 
 CC-17, Bluegrass Creek valley 
 
 at creek level 
 
 (about 590 ft elevation) 
 
 0.0 
 
 LLI 
 _J 
 
 lu 
 
 _j 
 
 < 
 
 0) 
 
 To 
 w 
 
 _>. 
 o 
 
 "O 
 
 >% 
 o 
 
 0.1 
 
 0.2 
 
 0.3 
 
 0.4 
 
 0.5 
 
 0.6 
 
 AI,on W Lomax 
 
 / "Mate Wisconsinan 
 
 Beardstown 
 
 earliest 
 
 Long Lake 
 (Petersburg) 
 
 Powdermilk Creek 
 (Petersburg equivalent) 
 
 Stenotrema 
 M-14; 113.5 ft 
 
 • ',CC-11 
 
 Riddle North 
 (Petersburg) 
 
 pre-lllinoian 
 Wildcat 
 
 Creek 
 
 -^ 
 
 County ^AJ 
 Line 
 
 0.0 0.1 0.2 0.3 0.4 0.5 0.6 
 
 free AILE/ILE 
 
 0.7 
 
 0.8 
 
 0.9 
 
 1.0 
 
 Figure 41 Plot of Aile/Ile in the total hydrolysate vs. Aile/Ile in the free hydrolysate of Stenotrema showing 
 that samples from the study area correlate with Petersburg Silt near the type area. 
 
 yr B.P. (ISGS-2073). The sample, taken from a depth of 
 4.5 feet at outcrop CC-18 (fig. 2), provided a minimum 
 age for the broad terrace surface adjacent to the pre- 
 sent-day streams of Bluegrass Creek and the North 
 Fork Embarras River. Corrections of the radiocarbon 
 age by Stuiver and Pearson (1986) put the age in calen- 
 dar years between 1474 and 1648 A.D. The age also 
 indicates that potential archeological sites in the valley 
 bottoms may be buried by thick alluvium. 
 
 Two radiocarbon ages from the Cahokia in Blue- 
 grass Creek are late Wisconsinan. A coniferous wood 
 fragment found in a buried, organic-rich horizon along 
 Bluegrass Creek at exposure CC-17 yielded an age of 
 23,720 ± 300 yr B.P. (ISGS-2113). Well preserved, conif- 
 erous wood fragments (probably spruce) from a depth 
 of 10.8 to 11.2 feet at boring M-120 (fig. 2) yielded an 
 age of 14,490 ± 140 yr B.P. (ISGS-2024). 
 
 70 
 
QUATERNARY GEOLOGICAL HISTORY AND 
 ENVIRONMENTS OF DEPOSITION 
 
 The glacial stratigraphy of the MAS is representative of 
 Fllinoian deposits in central Illinois. Pre-Illinoian till 
 units are not present at the site, but they are found 
 adjacent to the site. The large database for the MAS 
 allows detailed characterization of several units, in- 
 cluding their thickness and distribution within two 
 buried bedrock valleys. Interpretation of the environ- 
 ments of deposition of most units is limited to what can 
 be inferred from examination of core and isopach 
 maps. 
 
 Pre-Illinoian 
 
 The age of the regional buried bedrock valley system is 
 uncertain, but it is, in part, pre-Yarmouthian because 
 Lierle Clay occurs near the base of the bedrock valleys. 
 Regional evidence indicates that pre-Illinoian ice prob- 
 ably modified a preexisting drainage system primarily 
 by valley widening (Kempton et al. 1991), and by effec- 
 tively removing drainage divides with low relief. Al- 
 though pre-Illinoian tills are not present at the MAS, 
 the Casey till member of the Banner Formation is pres- 
 ent about 10 miles north, east, and west of the MAS 
 (CC-11, fig. 1; MacClintock 1929, Kettles 1980, Ford 
 1970, Fox 1987). Other Banner tills have been described 
 near Danville, Illinois (Johnson 1964, Johnson, Gross, 
 Moran 1971, Johnson et al. 1972). 
 
 Early Illinoian Martinsville Sand 
 and Petersburg Silt 
 
 The succession of sediments at the base of the buried 
 bedrock valleys was deposited primarily during the 
 early Illinoian. Yarmouthian Lierle Clay is present 
 along the flanks, but not along the bottoms, of the 
 buried bedrock valleys beneath and adjacent to the 
 MAS. No more than 25 feet of downcutting is inferred 
 to have occurred during deposition of the overlying 
 Martinsville sand when earliest Illinoian streams were 
 at or near the base of the Martinsville and the North 
 Fork Embarras bedrock valleys. These buried bedrock 
 valleys are now filled with the thickest known occur- 
 rences of several Illinoian units: the Petersburg Silt, and 
 the Smithboro Till, Mulberry Grove, and Vandalia Till 
 Members of the Glasford Formation. 
 
 The basal deposit of the succession, informally 
 named Martinsville sand, is composed of colluvium, 
 alluvium, and lacustrine sediment. Poorly expressed 
 pedogenic features, in addition to coniferous wood 
 fragments, indicate that the Martinsville sand accumu- 
 lated under cool climate at the beginning of the Illi- 
 noian Age. Features or products characteristic of 
 interglacial weathering, such as rounded subangular 
 blocky soil structure, cutans, krotovina (crayfish bur- 
 rows filled with black, clayey sediment; Follmer et al. 
 1979), and abundant clay particles <1 urn in diameter, 
 are not evident in any facies of the Martinsville sand. 
 Typical changes in clay mineralogy along weathering 
 profiles, such as loss of chlorite and an upward increase 
 
 in interstratified or expandable clay minerals (Willman 
 et al. 1966, Curry 1989), also are lacking. These charac- 
 teristics are common in the Lierle Clay (figs. 9, 10) and 
 the overlying Berry Clay Member (fig. 35), both of 
 which were pedogenically modified during inter- 
 glacial episodes. 
 
 Weakly developed soils, pulmonate gastropods, 
 concentrations of coniferous wood fragments, silt con- 
 tent, and laminations collectively indicate that the Pe- 
 tersburg Silt was deposited in a slackwater lake under 
 periglacial conditions (Curry and Follmer 1992). The 
 slackwater lake in the Embarras River valley formed 
 during the early Illinoian as the level of glacial melt- 
 water and fluvial sediment rose in the ancient Wabash 
 River valley. As an analogy, late Wisconsinan sedi- 
 ment, mapped as Equality Formation and deposited in 
 ancient Lake Embarras (Frye et al. 1972), occurs about 
 20 miles south of Martinsville along the Embarras River 
 (Lineback 1979a). 
 
 Illinoian Glasford Formation — Environment 
 of Deposition of Diamicton (Till) 
 
 Overlying the Petersburg Silt, till members belonging 
 to the Glasford Formation are the thickest and most 
 widespread lithostratigraphic units beneath the MAS. 
 Special discussion of their genesis helps to explain 
 lithologic features, physical characteristics, and distri- 
 bution across the site. Generally, three types of till 
 related to processes of deposition are recognized. They 
 are lodgement, deformation, and meltout tills. Deter- 
 mining what processes predominated during till depo- 
 sition requires careful study of outcrops or core 
 because sedimentary structures characteristic of one 
 process may have been modified by another process 
 (Boulton 1987, Hicock 1990). 
 
 Lodgement and deformation tills are interpreted to 
 have been deposited by active ice. Lodgement till re- 
 sults from debris released at the base of a sliding gla- 
 cier. Deformation till results from the plastic behavior 
 of sediment beneath the glacier as it is moved by the 
 shearing force of the glacier. This underlying sediment 
 is not incorporated into the glacial ice. Lodgement till 
 commonly is interpreted to have been deposited by 
 sliding "warm-based" glaciers that abraded bedrock 
 surfaces, or covered paleosols or proglacial sequences 
 with little or no deformation (Boulton 1972). Evidence 
 of deposition by a shearing or sliding glacial bed in a 
 lodgement environment includes bullet-shaped cob- 
 bles, strong pebble fabric, and U-shaped channels filled 
 with sand and gravel in diamicton (Eyles 1983, Drewry 
 1986, Johnson and Hansel 1990). 
 
 The theory that till deposition results from deform- 
 ing beds was recently advanced by Boulton (1987), 
 Boulton and Hindmarsh (1987), Alley et al. (1987), and 
 Alley (1991). Many tills thought to have been deposited 
 by lodgement are now thought to have been deposited 
 during the pervasive shear in a deforming bed. Some 
 
 71 
 
attributes thought to be diagnostic of lodgement may 
 be reinterpreted as features that support the deform- 
 ing-bed theory. For example, cobble pavements (or 
 stone lines), interpreted as partially eroded lag deposits 
 by advocates of the lodgement process, may be reinter- 
 preted as a lag deposit of a deforming bed (Clark 1991). 
 
 Deformation till includes masses of sediment in 
 which the primary sedimentary structure or sequence 
 has been disturbed (Boulton 1987). Deformation till 
 contains abundant fragments of underlying lithologies, 
 and the lower contact is erosional as indicated by trun- 
 cated subsequences. Deformation and lodgement may 
 be closely related; for example, diamicton originally 
 deposited by lodgement processes may be deformed 
 later. 
 
 Meltout till contains evidence for passive melting of 
 interstitial ice. Passive melting may result in interca- 
 lated deposits of sorted sediment and diamicton modi- 
 fied by soft-sediment deformation. Examples of 
 sedimentary structures associated with meltout till are 
 silt layers draped over cobbles or boulders (Shaw 
 1988). Meltout till may be deposited in a subglacial 
 environment or in the upper portion of an ablating 
 glacier, from which it subsequently may be redeposited 
 by mass wasting processes, such as sediment gravity 
 flow (Lawson 1982). 
 
 Smithboro Till Member 
 
 The Smithboro Till Member of the Glasford Formation 
 was deposited by the earliest Illinoian glacier in the 
 region. The silt loam diamicton facies of the Smithboro 
 is characterized by its great thickness and abundant 
 inclusions of weathered bedrock, Martinsville sand, 
 and most commonly, Petersburg Silt. Well preserved 
 fossil gastropods in the Smithboro suggest that under- 
 lying sediment was incorporated as blocks with little 
 internal deformation. Shearing also is indicated by 
 strongly developed platy structure imparted by crude 
 layering of silt loam and organic-rich, silty clay loam. 
 These features are suggestive of remolding of primary 
 sediment and associated structures. 
 
 The great thickness of the silt loam diamicton facies 
 of the Smithboro at the MAS probably is due to incor- 
 poration or reworking of Petersburg Silt, which was at 
 least 50 feet thick in the bedrock valleys before the 
 earliest Illinoian glacier covered the area. Several defor- 
 mational processes may account for the thick sections 
 of lacustrine silt incorporated in both facies of the 
 Smithboro (figs. 24, 25). For example, a cold-based gla- 
 cier may have incorporated frozen Petersburg Silt, or 
 alternatively, a warm-based glacier may have de- 
 formed normally or underconsolidated, saturated sedi- 
 ment. Differences in texture of the silt loam diamicton 
 facies may be explained by relative degrees of shearing 
 and remolding of sediment. 
 
 The loam diamicton facies is more uniform than the 
 silt loam diamicton facies with respect to texture and 
 structure. These differences may be explained by the 
 deforming-bed theory. Deposition of the loam diamic- 
 ton facies may have occurred during more pervasive 
 
 shear than the deposition of the silt loam diamicton 
 facies. Alternatively, the loam diamicton facies may 
 have been deposited by lodgement or regelation 
 (Drewry 1986). In either scenario, the composition of 
 the sediment at the base of the glacier changed as the 
 local silty and expandable clay-rich sediment became 
 covered with till and was not re-entrained by the gla- 
 cier. Composition of sediment higher in the sequence, 
 therefore, was influenced by proportionally more far 
 traveled sediment. The result is a till composition in the 
 loam diamicton facies that generally is less silty and 
 contains more illite relative to expandable clay miner- 
 als than till lower in the sequence. 
 
 Mulberry Grove Member 
 
 The distribution and physical characteristics of facies in 
 the Mulberry Grove Member indicate deposition in 
 subaerial proglacial and ice marginal or subglacial en- 
 vironments, but primarily in the latter (fig. 42). Evi- 
 dence for these environments abruptly changes 
 laterally and vertically. Successions that, in part, are 
 composed of the pedogenically modified and fossilifer- 
 ous silt facies (such as seen in core from borings M-03, 
 M-07 [fig. 24], and M-lll) are interpreted to have been 
 deposited subaerially in a proglacial environment. Suc- 
 cessions composed of diamicton and unaltered gray 
 silts that have a Vandalia-like mineralogy or texture are 
 interpreted to have been deposited in subglacial or ice 
 marginal environments. Because of the similar miner- 
 alogy of this part of the Mulberry Grove and Vandalia, 
 they are interpreted to have been deposited during the 
 same glacial advance. Evidence for the abrupt changes 
 in depositional environments is illustrated by features 
 shown in cross section A-A' (fig. 3). Subaerial pro- 
 glacial environments are indicated by pedogenically 
 altered silt in the Mulberry Grove Member at M-07, but 
 immediately to the west beneath CLK-02-03 and M- 
 101, subglacial erosion is indicated by truncation of the 
 Smithboro Till by the Mulberry Grove and Vandalia 
 Members. 
 
 A thick deposit of Mulberry Grove Member occurs 
 under the east part of the modern North Fork Embarras 
 River valley adjacent to the MAS (figs. 14, 26), and 
 consists of interbedded diamicton and sand and gravel. 
 The topography of the lower surface of the Mulberry 
 Grove Member (fig. 27) indicates that most of these 
 sediments may have been deposited in subglacial or ice 
 marginal drainageways associated with the glacial ad- 
 vance that deposited the Mulberry Grove and Vandalia 
 Till Members. Comparison of surface relief at the base 
 of the Mulberry Grove Member (fig. 27) with that of the 
 Vandalia Till Member (fig. 43) shows that the final 
 phases of deposition of the Mulberry were generally 
 aggradational. 
 
 Uniform Diamicton Facies, Vandalia 
 Till Member 
 
 The second advance of Illinoian ice in the region depos- 
 ited the Vandalia Till Member and part of the Mulberry 
 Grove Member of the Glasford Formation. The homo- 
 
 72 
 
geneity of texture and lack of primary or deformed 
 sedimentary structure suggest that the uniform 
 diamicton facies of the Vandalia was deposited by 
 lodgement (Eyles 1983, Ashley et al. 1985) or in a per- 
 vasively deforming bed (Alley et al. 1987). 
 
 The genesis of anomalously thick Vandalia and deep 
 Mulberry Grove sand and gravel near M-112 and 
 CLK-02-03 (fig. 11) is speculative. Such a shallow cone 
 (apex down) filled with glacigenic diamicton has not 
 been described in the literature. Truncation of units 
 indicate the cone is an erosional feature possibly 
 formed in concert with the channel that occurs on the 
 surface of the Smithboro Till Member (fig. 27). Present 
 data do not allow specific interpretation of the genesis 
 of these features (i.e., subglacial, ice marginal, or 
 glaciofluvial erosion). 
 
 Melange Facies, Vandalia Till Member 
 
 The melange facies of the Vandalia Till Member was 
 deposited by a combination of subglacial or ice mar- 
 ginal and supraglacial processes, and modified by pas- 
 sive loading and dewatering of relatively stagnant, 
 debris-rich ice. At outcrop CC-16, subparallel, discon- 
 tinuous layers, lenses, pods, and convoluted laminae of 
 well sorted, medium grained sand as much as 3 feet 
 thick and 30 feet long, are interbedded with layers of 
 loam diamicton and uniform silt (figs. 33b, 45). The 
 upper contacts of the sand layers commonly are irregu- 
 lar and wavy, which possibly was caused by soft sedi- 
 ment deformation during deposition and dewatering. 
 The sand bodies (or "rafts"; Ruszczynska-Szenajch 
 1987) may have been incorporated into the glacier bed 
 in the frozen state, and then transported to the site in a 
 deforming bed (Menzies 1990a, b). Shearing during 
 and after deposition destroyed any primary bedding 
 structures. 
 
 The soft-sediment deformation mentioned above re- 
 sulted in a relatively weak macrofabric; therefore, the 
 diamicton is interpreted, in part, as a meltout till. The 
 loam diamicton above and below the sand layers at 
 outcrop CC-16 contains numerous wavy sand part- 
 ings, and yields pebble macrofabrics with poorly ex- 
 pressed preferred orientations (SI values of 0.58 and 
 0.66 for macrofabrics A and B, respectively, in fig. 44). 
 For a discussion of the interpretation of pebble macro- 
 fabric data, see Lawson 1982. Evidence for deposition 
 by primarily lodgement processes is lower in the sec- 
 tion, where the melange facies yields a pebble fabric 
 (macrofabric C in fig. 44) with a strong preferred orien- 
 tation (SI value of 0.81) of approximately S 32° W, the 
 inferred direction of ice movement. The diamicton also 
 contains abundant striated, bullet-shaped cobbles and 
 discontinuous cobble-rich layers. Such characteristics 
 are interpreted to indicate deposition by lodgement 
 (Eyles 1983, Johnson and Hansel 1990) or possibly at 
 the base of a deforming bed (Clark 1991). Thus, the 
 melange facies at CC-16 appears to have been depos- 
 ited in a stagnating, ice-marginal environment as 
 lodgement till, or initially deposited in a deforming bed 
 and later deposited or modified by meltout processes. 
 
 The melange facies at outcrop CC-15 consists of 
 irregularly shaped pods of gravelly sand that are asso- 
 ciated with thin layers of loam diamicton (fig. 46). Mix- 
 ing of gravelly sand and diamicton did not occur, 
 although diamicton layers are commonly less than 0.1 
 inch thick. Brittle fracturing of the sand and gravel, 
 followed by filling of the fractures with fluid diamic- 
 ton, may be explained by high hydrostatic pressure 
 and partial dewatering of frozen sediment during 
 deposition. Because a larger volume of ice or water 
 would be in contact with grain surfaces in the diamic- 
 ton than with those in the sand and gravel, it is possible 
 that, with loading, the interstitial water in the diamic- 
 ton was fluid, while the interstitial water in the sand 
 and gravel remained frozen. Under great hydrostatic 
 pressure and radial tensional shear stress, the bodies of 
 sand, gravel, and ice may have deformed as a brittle 
 solid, while the surrounding diamicton was suffi- 
 ciently fluid to flow in the voids between fracture faces. 
 
 The specific mechanisms that formed the disconti- 
 nuities in the melange facies are not well understood, 
 but multiple modes or episodes of formation probably 
 occurred. The genesis of fracturing and discontinuities 
 in the melange facies can be divided into primary and 
 secondary mechanisms. Primary mechanisms likely to 
 have affected the melange facies include deformation 
 and faulting during compaction and dewatering, dif- 
 ferential compaction, and stresses from loading and 
 unloading of ice or ice movement (Connell 1984). Sec- 
 ondary mechanisms likely to have affected the melange 
 facies include desiccation cracking, stress release, 
 weathering, periglacial processes, and ice-wedge for- 
 mation under ancient permafrost conditions. The verti- 
 cally oriented sand-filled joints at CC-15 (fig. 33a) may 
 have formed as ice-wedge casts during the late Illi- 
 noian. Battelle Memorial Institute and Hanson Engi- 
 neers, Inc. (1990a) provide a more detailed discussion 
 of fracture genesis and character at the MAS. 
 
 Late and Post-Illinoian Deposits, Weathering, 
 and Development of Stream Network 
 Upland surfaces Sand and gravel and patchy lacus- 
 trine sediments belonging to the late Illinoian Pearl 
 Formation were initially deposited on upland surfaces 
 during melting of the glacier that deposited the Van- 
 dalia Till Member. These sediments were partly buried 
 by colluvium and weathered during the Sangamonian 
 Age. Composed of soft, expandable, clay-rich diamic- 
 ton, this sediment is the Berry Clay Member. Weather- 
 ing and bioturbation of surficial sediment continued as 
 the first Wisconsinan loess (Roxana Silt) was deposited 
 at the MAS. Less sand and finer pedogenic features in 
 the lower part of the overlying Peoria Loess indicate 
 that less bioturbation and weathering occurred during 
 the late Wisconsinan than during the Sangamonian and 
 early to middle Wisconsinan. The most likely origin of 
 the Parkland Sand and the relatively high sand content 
 of the loess at the MAS (compared to the regional mean 
 of Fehrenbacher et al. 1986) was locally sandy alluvium 
 in the floodplain of the North Fork Embarras River. For 
 
 73 
 
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 % 
 
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 60 
 
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 75 
 
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 9 
 60 
 
 77 
 
-CC-16 
 
 trend = 8° 
 plunge = 4° 
 S, = 066 
 
 Bluegrass Cr 
 
 Figure 44 Outcrop CC-16 along Bluegrass Creek, immediately north of 
 the MAS, and pebble macrofabrics from the melange facies of the Vandalia 
 Till Member, Glasford Formation. 
 
 about the last 10,000 years, the mantle of late glacial and 
 postglacial sediment has been weathered under a cli- 
 mate similar to that of today (Willman and Frye 1970). 
 
 Upland slopes Throughout the study area, the San- 
 gamon Soil occurs on uplands, as well as along gentle 
 valley slopes extending to about 30 feet above the major 
 streams. The depth of leaching and other pedogenic 
 alteration below these slopes is shallower than on the 
 uplands. The thin mantle of Wisconsinan loess above 
 the Sangamon Soil on slopes indicates that sediment 
 was transported during the late Sangamonian (Johnson 
 et al. 1972). Erosion has stripped any postglacial loess 
 or upper soil horizons of the Sangamon Soil from slopes 
 extending from major floodplains to about 30 feet above 
 the floodplains. 
 
 Valleys Development of the drainage network on 
 and immediately adjacent to the MAS may have begun 
 after deposition of the Pearl Formation and upper Van- 
 dalia Till Member. In this model, the stream valleys 
 were incised into a nearly continuous upland surface. 
 Alternatively, the present position of the North Fork 
 Embarras valley may be related to subglacial drainage 
 of the glacier that deposited the Mulberry Grove and 
 Vandalia Till Members. In this scenario, the proto- 
 North Fork Embarras River valley was initially a pri- 
 mary conduit for proglacial and subglacial discharge; 
 less diamicton is present in the valley not because of 
 erosion, but because diamicton was never deposited 
 there. Boulton and Hindmarsh (1987) postulated a simi- 
 lar model of subglacial deposition in the development 
 of tunnel valleys under warm-based glaciers. When the 
 Vandalia glacier melted, the valley of the North Fork 
 
 78 
 
Figure 45 Sediment types of the melange facies of the Vandalia Till Member, Glasford Formation, at CC-16. 
 Area of photograph outlined in figure 44. 
 
 Embarras River may have been a route for meltwater 
 from glacial activity north of the MAS during the upper 
 Illinoian (Johnson et al. 1972, Lineback 1979a, b). Later, 
 the valley was a route for drainage during the San- 
 gamonian, Wisconsinan, and Holocene. 
 
 The age of most postglacial sediments in the North 
 Fork Embarras River valley adjacent to the MAS ap- 
 pears to be younger than the upland postglacial se- 
 quences at the MAS. The upper silt loam facies of the 
 Cahokia Alluvium in the valley of the North Fork Em- 
 barras River is Holocene, based on a radiocarbon age of 
 ca. 8,300 yr B.P. from the base of the facies at H-l. The 
 underlying sand and gravel facies of the Cahokia in this 
 valley is largely composed of reworked late Wisconsi- 
 nan outwash, or less likely, reworked late Illinoian 
 outwash. 
 
 As was observed by Hajic (1990) in the Illinois and 
 Mississippi River valley area, older alluvial sediment is 
 more commonly preserved in tributary valleys than in 
 the valleys of master streams. Patches of pre-Holocene 
 sediment have been preserved in the alluvium of Blue- 
 grass Creek, including a narrow terrace at CC-17 that 
 contains a thin, wavy band of organic material and 
 wood fragments that yielded an age of 23,720 ± 300 yr 
 B.P. (ISGS-2113). From the Illinoian to the present, the 
 lowest elevation Bluegrass Creek may have attained 
 during periods of downcutting was about 557 feet, 
 which is the elevation of the bedrock surface at M-120 
 near the mouth of Bluegrass Creek (fig. 2). At about 
 
 14,500 yr B.P., the mouth of Bluegrass Creek was no 
 more than about 4 feet above its present level of about 
 575 feet, as indicated by the radiocarbon age (ISGS- 
 2024) on wood from a depth of about 11 feet at M-120. 
 This suggests net aggradation in the valley some time 
 after 14,500 yr B.P., followed by incision to present 
 stream levels during an unknown period. 
 
 Figure 46 Sand and gravel bodies (stippled) in 
 loam diamicton of the melange facies are suggestive 
 of soft sediment deformation under hydrostatic 
 loading. 
 
 79 
 
SUMMARY AND CONCLUSIONS 
 
 Quaternary deposits beneath the MAS fill two buried 
 bedrock valleys (the Martinsville and North Fork Em- 
 barras bedrock valleys) above sandstone, siltstone, and 
 shale of the Pennsylvanian Bond and Modesto Forma- 
 tions. The Martinsville bedrock valley had not been 
 mapped prior to the MAS investigations. Pre-Illinoian 
 deposits were not encountered at the MAS, but they are 
 found 3 miles east of the MAS. The thicknesses of each 
 primary Illinoian lithostratigraphic unit, including the 
 Petersburg Silt, and the Smithboro Till, Mulberry 
 Grove, and Vandalia Till Members of the Glasford For- 
 mation, are the greatest known in Illinois. Glacial drift 
 varies in thickness from about 70 feet to more than 200 
 feet at the MAS, but it is absent in the valley of Blue- 
 grass Creek just north of the site. 
 
 The base of the Quaternary succession at the MAS is 
 the Yarmouthian Lierle Clay, composed of pedogeni- 
 cally altered sediment no more than 2 feet thick. This 
 unit is overlain by the early Illinoian Martinsville sand, 
 which was deposited during cool climate, and by as 
 much as 50 feet of Petersburg Silt, interpreted as slack- 
 water lacustrine sediment. 
 
 Silt loam and loam till of the Smithboro Member of 
 the Glasford Formation, as much as 97 feet thick, over- 
 lies the Petersburg. The Smithboro is interpreted to 
 have been deposited as subglacial till, initially by defor- 
 mational processes and lodgement, and later by pri- 
 marily lodgement or a deforming bed. 
 
 The overlying Mulberry Grove Member has three 
 facies composed of diamicton, silt, and sand and 
 gravel, primarily the latter. The Mulberry Grove Mem- 
 ber was deposited under two contrasting environ- 
 ments. In subaerial proglacial environments, 
 pedogenically altered fossiliferous silt was deposited, 
 whereas in subglacial and ice marginal environments, 
 sand and gravel and loam diamicton were deposited. 
 
 The Vandalia Till Member of the Glasford Forma- 
 tion has two facies, a lower uniform diamicton and a 
 melange facies. The uniform diamicton facies, as much 
 as 129 feet thick, is composed of loam diamicton depos- 
 ited subglacially by lodgement or by pervasive shear in 
 a deforming bed. Subglacial channels filled with poorly 
 sorted sand and gravel as much as 18.5 feet thick also 
 occur in the uniform diamicton facies; however, the 
 
 length, continuity, and width of the channels are un- 
 known. The melange facies, as much as 34 feet thick, 
 typically overlies the uniform diamicton facies. The 
 melange consists chiefly of loam diamicton, with nu- 
 merous discontinuities, inclusions and lenses of sand, 
 and few inclusions of silt. The melange facies was de- 
 posited in subglacial and ice marginal environments. 
 
 The Glasford Formation is overlain discontinuously 
 by sand and gravel of the Pearl Formation, which is as 
 much as 13 feet thick. The overlying Berry Clay Mem- 
 ber is composed of leached loam and clay loam diamic- 
 ton no more than 12 feet thick. The Pearl and Berry, as 
 well as the upper melange facies of the Vandalia, are 
 leached and pedogenically modified by the Sangamon 
 Soil. The Berry Clay Member is overlain by Wisconsi- 
 nan loess as thick as 7 feet, including a lower zone of 
 pedogenically mixed loess and weathered sediment 
 composed of loam (Roxana Silt) and silt loam (Peoria 
 Loess). Both units are pedogenically modified — the 
 Roxana by the Farmdale Soil and the Peoria by the 
 modern soil. 
 
 Streams and terraces along the North Fork Embarras 
 River, Bluegrass Creek, Kettering Branch, and smaller 
 valleys are underlain by Cahokia Alluvium. The Ca- 
 hokia, as much as 35 feet thick, is composed of coarse 
 granular sediment, well sorted medium sand, loam, 
 and silt loam. Radiocarbon ages of 23,720 ± 300 yr B.P. 
 (ISGS-2113), 14,490 ± 140 yr B.P. (ISGS-2024), 8,370 ± 
 300 yr B.P. (ISGS-2176), and 320 ± 70 yr B.P. (ISGS-2073) 
 from wood within the Cahokia indicate an age that 
 ranges from late Wisconsinan to Holocene. The pres- 
 ence of late Wisconsinan sand and gravel outwash 
 (Henry Formation) cannot be confirmed in the valley of 
 the North Fork Embarras River because neither the 
 Roxana Silt, Berry Clay Member, nor Sangamon Soil is 
 preserved in the valley. 
 
 Development of the drainage network on and imme- 
 diately adjacent to the MAS probably began in the 
 Illinoian during and after deposition of the Pearl For- 
 mation and the melange facies of the Vandalia Till 
 Member. Much of the relief across the North Fork 
 Embarras River valley may have developed earlier 
 during the time the Mulberry Grove Member and the 
 Vandalia Till Member were deposited. 
 
 ACKNOWLEDGMENTS 
 
 The authors are grateful to the following reviewers 
 whose comments improved the manuscript: Donald 
 Ballman, Battelle Memorial Institute; Daniel N. Clayton 
 and Ronald R. Nicks, Shannon & Wilson, Inc.; W. Hil- 
 ton Johnson, University of Illinois; Leon R. Follmer, 
 
 Ardith K. Hansel, and E. Donald McKay III, Illinois 
 State Geological Survey; and Robert Redman. Barry 
 Miller, Kent State University, identified the gastropod 
 shells, and William McCoy, University of Massachu- 
 setts at Amherst, provided amino acid analyses. 
 
 80 
 
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 83 
 
Appendix Mean values ol particle-size determinations, semiquantitative mineralogical analyses, and selected physical characteristics. 
 
 
 
 Particle 
 
 size distribution 
 
 
 Coefficient of 
 uniformity, Cu 
 
 Moisture 
 content, % 
 
 
 Atterberg limits 
 
 
 
 Total 
 gravel, % 
 
 
 <2 mm, % 
 
 
 Liquid 
 limit, % 
 
 Plastic 
 limit, % 
 
 Plasticity 
 
 Unit 
 
 Sand 
 
 SIN 
 
 Clay 
 
 index 
 
 Cahokia Alluvium (c) 
 silt loam fades 
 (c-sl) 
 
 0.6±1.1 
 29(0-5) 
 
 16.7113.1 
 29(2-53) 
 
 53.1113.2 
 29(32-82) 
 
 30.1111.9 
 29(7-59) 
 
 24.6119.2 
 16(4.0-68.0) 
 
 23.818.5 
 16(14.8-51.5) 
 
 34.019.5 
 15(16-51) 
 
 16.813.6 
 15(14-26) 
 
 17.118.4 
 15(0-37) 
 
 sand and gravel 
 lacies (c-z) 
 
 12.4±21.5 
 27(0-84) 
 
 87.119.0 
 27(64-97) 
 
 7.916.0 
 27(1-23) 
 
 5.013.5 
 27(2-16) 
 
 25.0141.1 
 27(1.8-207.5) 
 
 19.214.8 
 25(8.5-29.1) 
 
 - 
 
 - 
 
 - 
 
 Peona Loess (p) 
 
 0.5±0.8 
 37(0-3) 
 
 10.214.1 
 37(4-21) 
 
 55.516.1 
 37(44-69) 
 
 34.217.6 
 37(20-49) 
 
 7.916.3 
 32(0.6-18.5) 
 
 24.913.8 
 34(14-32) 
 
 40.819.7 
 18(28-60) 
 
 17.912.3 
 18(14-22) 
 
 22.9111.0 
 18(7-44) 
 
 Ftoxana Silt, sandy-silt 
 facies (r) 
 
 1.211.4 
 31(0-6) 
 
 25.216.5 
 31(6-38) 
 
 40.814.8 
 31(27-48) 
 
 33.815.5 
 31(20-46) 
 
 15.5111.8 
 26(1.0-54.8) 
 
 20.513.7 
 27(8.8-28.7) 
 
 33.818.1 
 20(25-54) 
 
 13.611.7 
 20(11-18) 
 
 25.218.1 
 29(8-37) 
 
 Pearl Formation (pe) 
 
 3.0±4.1 
 12(0-15) 
 
 74.5121.9 
 12(14-95) 
 
 11.7110.7 
 12(3-37) 
 
 13.7113.6 
 12(0-54) 
 
 83.7169.2 
 8(2.6-255.0) 
 
 18.416.9 
 8(4.8-27.0) 
 
 — 
 
 - 
 
 - 
 
 Berry Clay Member (peb) 
 and (gb) 
 
 3.7±2.8 
 
 75(0-16) 
 
 37.019.5 
 75(14-64) 
 
 30.117.4 
 75(15-47) 
 
 32.716.4 
 75(13-47) 
 
 44.9148.5 
 68(1.5-185.0) 
 
 20.113.4 
 70(14.0-40.9) 
 
 35.216.3 
 46(21-48) 
 
 12.311.6 
 46(8-17) 
 
 22.916.0 
 46(6-35) 
 
 Glaslord Formation 
 Vandalia Till Member 
 melange facies 
 weathered diamicton 
 (gv-mx) 
 
 5.513.2 
 6(3-11) 
 
 44.514.4 
 6(39-52) 
 
 28.716.2 
 6(22-38) 
 
 26.613.8 
 6(22-31) 
 
 134.116.4 
 3(125.2-139.6) 
 
 11.911.7 
 3(9.7-13.9) 
 
 - 
 
 - 
 
 - 
 
 oxidized diamicton 
 (gv-mo) 
 
 5.814.3 
 43(1-28) 
 
 45.615.0 
 68(32-63) 
 
 30.713.5 
 68(22-39) 
 
 23.614.2 
 68(11-31) 
 
 71.1166.1 
 42(1.5-312.3) 
 
 11.814.6 
 42(6.1-25.0) 
 
 21.5+3.1 
 24(15-28) 
 
 11.811.2 
 24(10-15) 
 
 9.6+3.0 
 24(3-15) 
 
 unoxidized diamicton 
 (gv-m) 
 
 8.015.2 
 93(1-33) 
 
 44.717.8 
 93(14-65) 
 
 33.317.7 
 93(19-68) 
 
 21.915.4 
 93(8-40) 
 
 100.2+56.8 
 93(4.5-298.6) 
 
 8.812.2 
 95(4.1-19.4) 
 
 20.613.7 
 80(14-41) 
 
 11.010.9 
 80(8-14) 
 
 9.613.0 
 80(3-28) 
 
 unoxidized sand and 
 gravel (gv-mz) 
 
 5.915.3 
 13(0-19) 
 
 88.316.0 
 13(77-96) 
 
 7.814.8 
 13(2-17) 
 
 3.811.6 
 13(1-6) 
 
 10.3112.0 
 13(2.5-38.4) 
 
 16.714.1 
 11(10.0-25.9) 
 
 — 
 
 - 
 
 - 
 
 uniform diamicton 
 facies (gv-u) 
 
 8.414.8 
 513(0-41) 
 
 42.414.7 
 522(14-71) 
 
 35.114.8 
 522(19-76) 
 
 22.413.4 
 522(3-38) 
 
 86.6162.8 
 482(1.5-903.6) 
 
 9.911 .6 
 479(4.7-21.3) 
 
 21.912.2 
 392(17-44) 
 
 1 1 .810.9 
 392(8-18) 
 
 10.112.2 
 392(1-31) 
 
 total diamicton, 
 Vandalia Till Member 
 
 8.314.9 
 606(0-41) 
 
 42.715.4 
 615(14-71) 
 
 34.815.4 
 615(19-76) 
 
 22.313.8 
 615(8-40) 
 
 105.7153.9 
 575(1.5-903.6) 
 
 9.711.8 
 574(4.1-21.3) 
 
 21.712.6 
 472(14-44) 
 
 11.611.0 
 472(8-18) 
 
 10.012.5 
 472(1-31) 
 
 unoxidized sand and 
 gravel facies (gv-z) 
 
 9.219.7 
 25(0-38) 
 
 79.8113.8 
 26(56-96) 
 
 14.1110.9 
 26(2-35) 
 
 6.113.9 
 26(1-13) 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 Mulberry Grove Member 
 sand and gravel 
 facies (gm-z) 
 
 19.7119.3 
 69(0-77) 
 
 84.2112.7 
 69(48-97) 
 
 11.219.9 
 69(1-41) 
 
 4.513.2 
 69(1-17) 
 
 23.7133.8 
 63(2.0-176.5) 
 
 14.815.3 
 60(6.0-36.4) 
 
 - 
 
 - 
 
 - 
 
 diamicton facies 
 (gm-d) 
 
 11.616.8 
 35(3-30) 
 
 42.317.0 
 35(31-62) 
 
 37.715.8 
 35(24-47) 
 
 19.814.1 
 35(8-27) 
 
 97.8150.0 
 31(10.7-229.4) 
 
 11.212.9 
 29(5.2-19.5) 
 
 20.411.8 
 25(16-25) 
 
 12.010.7 
 25(11-13) 
 
 8.411 .8 
 25(3-12) 
 
 silly loam facies 
 (gm-s) 
 
 2.112.0 
 12(0-8) 
 
 17.319.3 
 12(5-38) 
 
 63.3113.1 
 12(38-78) 
 
 19.217.1 
 12(10-34) 
 
 17.716.1 
 12(4.5-25.1) 
 
 17.315.4 
 12(11.0-32.8) 
 
 28.017.8 
 9(21-46) 
 
 18.415.7 
 9(12-32) 
 
 9.616.9 
 9(0-20) 
 
 Smithboro Till Member 
 loam diamicton 
 facies (gs) 
 
 6.714.2 
 134(0-24) 
 
 31.116.2 
 138(26-70) 
 
 43.816.8 
 138(17-56) 
 
 25.016.3 
 
 138(8-45) 
 
 46.6+26.8 
 111(11 4-209 7) 
 
 13.112.2 
 124(9.0-23.2) 
 
 25.813.3 
 107(18-40) 
 
 13.411.4 
 107(11-22) 
 
 12.413.5 
 107(1-28) 
 
 silt loam diamicton 
 facies (gs-s) 
 
 3.613.0 
 230(0-17) 
 
 18.414.5 
 233(2-25) 
 
 56.718.0 
 233(26-83) 
 
 24.715.7 
 233(10-52) 
 
 24.716.2 
 209(3.0-45.6) 
 
 17.312.9 
 222(10.1-31.8) 
 
 28.413.7 
 207(21-61) 
 
 15.6±2.1 
 207(11-27) 
 
 12.814.2 
 207(0-44) 
 
 total diamicton, 
 Smithboro.Till Member 
 
 4.713.8 
 364(0-24) 
 
 23.118.0 
 371(2-70) 
 
 51.919.8 
 371(17-83) 
 
 24.815.9 
 371(8-52) 
 
 32.2119.5 
 320(0-209.7) 
 
 15.813.3 
 346(9-32) 
 
 27.513.8 
 314(18-61) 
 
 14.9+2.2 
 314(11-27) 
 
 12.614.0 
 314(0-44) 
 
 sand and gravel 
 facies (gs-z) 
 
 23.3127.7 
 6(2-77) 
 
 76.1111.5 
 8(61-93) 
 
 15.717.0 
 8(4-25) 
 
 8.115.1 
 8(2-17) 
 
 — 
 
 12.515.8 
 
 6(4.4-19.2) 
 
 — 
 
 — 
 
 - 
 
 Petersburg Silt (ps) 
 
 1 .313.4 
 62(0-16) 
 
 11.2116.1 
 62(0-94) 
 
 66.8114.9 
 62(3-90) 
 
 21.9+9.9 
 62(3-47) 
 
 — 
 
 22.114.4 
 57(9.4-32.7) 
 
 28.914.6 
 47(21-45) 
 
 18.912.9 
 47(14-25) 
 
 10.015.2 
 47(0-23) 
 
 Martinsville sand 
 sand and gravel 
 facies (ms-z) 
 
 18.8122.7 
 51(0-90) 
 
 79.8110.8 
 51(51-95) 
 
 13.417.8 
 51(0-36) 
 
 7.116.5 
 51(0-38) 
 
 36.9144.5 
 45(2.5-156.8) 
 
 7.417.1 
 49(6.9-42.5) 
 
 - 
 
 - 
 
 - 
 
 silty clay facies 
 (ms-s) 
 
 0.610.7 
 16(0-2) 
 
 22.9116.5 
 16(2-52) 
 
 42.1118.6 
 16(14-77) 
 
 34.6117.8 
 16(13-76) 
 
 6.418.4 
 15(2.4-36.9) 
 
 19.112.7 
 15(15-23) 
 
 46.0+3.3 
 3(42-50) 
 
 15.311.9 
 3(14-18) 
 
 30.611.9 
 3(28-32) 
 
 diamicton facies 
 (ms-d) 
 
 10.2110.3 
 16(0-31) 
 
 36.7113.7 
 16(6-59) 
 
 38.519.3 
 16(23-55) 
 
 23.6+10.7 
 16(5-51) 
 
 53.5145.9 
 12(3.1-149.0) 
 
 17.612.8 
 
 12(13.4-23.1) 
 
 27.114.8 
 8(22-38) 
 
 15.113.3 
 8(12-23) 
 
 12.014.2 
 
 8(7-22) 
 
 Banner Formation 
 Lierle Clay 
 Member (bl) 
 
 4.0119.5 
 12(0-35) 
 
 28.7111.8 
 12(7-54) 
 
 40.2113.6 
 12(26-70) 
 
 31.118.0 
 12(17-48) 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 Casey till member 
 oxidized (bc-o) 
 
 - 
 
 30.515.1 
 16(23-44) 
 
 39.815.3 
 16(31-52) 
 
 29.914.2 
 16(21-37) 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 Casey till member 
 unoxidized (be) 
 
 - 
 
 37.616.9 
 12(25-46) 
 
 38.214.4 
 12(32-48) 
 
 24.214.8 
 12(19-36) 
 
 — 
 
 - 
 
 - 
 
 - 
 
 — 
 
Appendix continued 
 
 
 
 
 M 
 
 ineratogy ol the <2 
 
 urn traction 
 
 
 
 
 
 Unit 
 
 Expandable clay 
 minerals. % 
 
 lllite, % 
 
 Chlorite & 
 kaolimte. % 
 
 Calcite. cps 
 
 Dolomite 
 cps 
 
 Vermiculite 
 
 index 
 
 Diffraction 
 intensity ratio 
 
 Heterogeneous 
 swelling index 
 
 Total counts 
 per second 
 
 Cahokia Alluvium (c) 
 silt loam tacies 
 
 (C-8l) 
 
 49.8116.6 
 30(10-79) 
 
 34.2112.3 
 30(14-59) 
 
 16.616.1 
 30(0-35) 
 
 1.6±6.6 
 30(0-35) 
 
 1.817.6 
 30(0-40) 
 
 29.9±9.6 
 30(11-46) 
 
 1.410.3 
 30(0.7-2.0) 
 
 9416.8 
 30(1-24) 
 
 206911215 
 30(641-5200) 
 
 sand and gravel 
 tacies (c-z) 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 Peona Loess (p) 
 
 53.2*14.6 
 28(27-82) 
 
 27.719.2 
 28(11-44) 
 
 19.017.1 
 28(7-36) 
 
 -0- 
 28(0-0) 
 
 -0- 
 27(20-55) 
 
 38.4±8.2 
 27(20-55) 
 
 1.010.4 
 28(0.7-2.0) 
 
 7214.6 
 27(1-19) 
 
 2173H024 
 28(610-3980) 
 
 Roxana Sift, sandy-silt 
 tacies (r) 
 
 67.5112.0 
 24(37-87) 
 
 18.618.5 
 24-(6-44) 
 
 13.7±4.3 
 24(7-23) 
 
 •0- 
 24(0-0) 
 
 -0- 
 
 24(0-0) 
 
 46.9±7.6 
 23(32-59) 
 
 0.9±0.3 
 24(0.6-1.6) 
 
 8.0146 
 24(3-26) 
 
 321711513 
 
 24(750-6450) 
 
 Peart Formation (pe) 
 
 37 3119.3 
 6(13-59) 
 
 47.6116.2 
 6(28-70) 
 
 15.0±5.4 
 6(7-23) 
 
 5.0±11.2 
 6(0-31) 
 
 10.0122.4 
 6(0-60) 
 
 — 
 
 2.110.8 
 6(1.3-38) 
 
 6.316.9 
 6(0-18) 
 
 23901822 
 6(1410-3680) 
 
 Berry Clay Member (peb) 
 and(gb) 
 
 59.4H8.0 
 63(11-89) 
 
 26.7115.5 
 
 63(6-71) 
 
 13.614.7 
 63(4-23) 
 
 0.514.1 
 63(0-33) 
 
 0.413.5 
 63(0-28) 
 
 41.0113.0 
 63(4-69) 
 
 1.310.6 
 63(0.4-3.3) 
 
 8.116.6 
 63(0-28) 
 
 3235H761 
 63(1050-7890) 
 
 Glastord Formation 
 
 Vandalia Till Member 
 
 melange tacies 
 
 weathered diamicton 
 
 (gv-mx) 
 
 29.1 ±7.1 
 9(15-38) 
 
 59.1 ±8.2 
 9(49-72) 
 
 11.7±2.8 
 8(8-17) 
 
 9.0+18.0 
 5(0-45) 
 
 7.0114.0 
 5(0-35) 
 
 20.0+6.2 
 8(8-25) 
 
 3.611.3 
 9(1.9-6.0) 
 
 4.6+3.3 
 5(0-10) 
 
 24991856 
 5(1790-4126) 
 
 oxidized diamicton 
 (gv-mo) 
 
 18.2±7.0 
 86(5-60) 
 
 66.1 ±6.5 
 86(40-80) 
 
 15.613.8 
 
 86(7.24) 
 
 42.2129.1 
 84(0-207) 
 
 36.4±27.3 
 84(0.227) 
 
 11.416.3 
 56(2-34) 
 
 3.011.0 
 86(1.7-7.3) 
 
 1.411.7 
 52(0-6) 
 
 20301546 
 54(1070-3500) 
 
 unoxidized diamicton 
 (gv-m) 
 
 12.5±6.2 
 80(7-44) 
 
 59.316.6 
 80(26-69) 
 
 28.1 ±3.4 
 
 80(15-35) 
 
 57.4118.0 
 80(0-100) 
 
 39.9110.8 
 (0-72) 
 
 5.7+6.6 
 80(-3-31) 
 
 1.4+0.3 
 80(0.5-3.1) 
 
 0.2-0.8 
 81(0-6) 
 
 2461+495 
 80(1620-3860) 
 
 unoxidized sand and 
 gravel (gv-mz) 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 uniform diamicton 
 tacies (gv-u) 
 
 12.4±4.1 
 401(3-40) 
 
 57.514.3 
 401(42-74) 
 
 29.9±3.3 
 401(12-39) 
 
 49.2114.8 
 401(10-98) 
 
 34.7111.0 
 401(0-75) 
 
 6.414.7 
 380(-6-40) 
 
 1.3+0.3 
 401(0.8-3.9) 
 
 0.1+0.6 
 382(0-10) 
 
 2493+523 
 380(890-5090) 
 
 total diamicton, 
 Vandalia Till Member 
 
 12.4±4.5 
 481(3-44) 
 
 57.814.8 
 481(26-74) 
 
 29.6-3.4 
 481(12-39) 
 
 50.6115.7 
 481(0-100) 
 
 35.6111.2 
 481(0-75) 
 
 6.315.0 
 460(-6-40) 
 
 1.310.3 
 481(0.5-3.9) 
 
 0.1+0.7 
 463(0-10) 
 
 24881518 
 460(890-5090) 
 
 unoxidized sand and 
 gravel (gv-z) 
 
 - 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 — 
 
 Mulberry Grove Member 
 sand and gravel 
 tacies (gm-z) 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 diamicton tacies 
 (gm-d) 
 
 12.1±6.0 
 49(3-30) 
 
 60.216.8 
 49(45-76) 
 
 27.613.7 
 49(17-36) 
 
 42.9116.1 
 49(0-115) 
 
 35.4113.1 
 49(0-97) 
 
 3.8+8.1 
 49(- 16-22) 
 
 1.5+0.4 
 49(1 .0-2.9) 
 
 0.2+0.8 
 49(0-4) 
 
 2615+642 
 49(1250-4020) 
 
 sifty loam tacies 
 (gm-s) 
 
 22.9111.1 
 20(9-53) 
 
 49.8110.8 
 20(22-64) 
 
 27.2+2.9 
 20(24-33) 
 
 32.9+22.3 
 20(0-95) 
 
 22.8+17.2 
 
 20(0-57) 
 
 14.1110.2 
 20(-7-32) 
 
 1.2+0.3 
 20(0.5-1.7) 
 
 1.712.3 
 20(0-9) 
 
 2268+809 
 20(840-3880) 
 
 Smithboro Till Member 
 loam diamicton tacies 
 <9S) 
 
 22.619.1 
 126(5-48) 
 
 48.8±5.9 
 126(29-61) 
 
 28.415.5 
 126(20-45) 
 
 34.3113.3 
 126(0-61) 
 
 25.2110.3 
 126(0-45) 
 
 16.617.3 
 125(0-33) 
 
 1.210.2 
 125(0.5-1.8) 
 
 1.0+1.5 
 122(0-9) 
 
 24591576 
 122(1150-4976) 
 
 silt loam diamicton 
 tacies (gs-s) 
 
 29.2+9.3 
 
 150(6-64) 
 
 42.517.1 
 150(17-59) 
 
 28.216.5 
 150(16-51) 
 
 24.5113.6 
 15(0-50) 
 
 21.2112.2 
 
 150(0-50) 
 
 23.1 ±6.3 
 
 146(9-45) 
 
 1.1+0.3 
 150(0.4-2.0) 
 
 1.6+2.0 
 146(0-8) 
 
 2294+669 
 148(880-4760) 
 
 total diamicton 
 Smithboro Til Member 
 
 26.2±9.7 
 
 276(5-64) 
 
 45.417.3 
 276(17-61) 
 
 28.316.1 
 276(16-51) 
 
 29.0114.3 
 276(0-61) 
 
 23.0111.6 
 276(0-50) 
 
 20.217.5 
 268(0-45) 
 
 1.110.3 
 268(0.4-2.0) 
 
 1 311 8 
 275(0-9) 
 
 2368+634 
 270(880-4970) 
 
 sand and gravel 
 tacies (gs-z) 
 
 — 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 Petersburg Sift (ps) 
 
 18.817.1 
 37(12-51) 
 
 51.7±6.4 
 37(31-62) 
 
 29.3+5.0 
 37(18-46) 
 
 21.6114.6 
 37(0-48) 
 
 16.2112.5 
 37(0-37) 
 
 16.016.4 
 38(7-37) 
 
 1.210.2 
 37(0.6-1 7) 
 
 0.811.9 
 37(0-10) 
 
 18401531 
 37(900-2900) 
 
 Martinsville sand 
 sand and gravel 
 facies (ms-z) 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 - 
 
 sifty day tacies 
 (ms-s) 
 
 22.3113.0 
 20(2-45) 
 
 426±18.3 
 20(16-85) 
 
 35.0110.1 
 
 20(9-57) 
 
 7.6113.5 
 20(0-40) 
 
 4.3110.5 
 20(0-37) 
 
 19.4112.2 
 20(-8-36) 
 
 1.111.2 
 20(0.2-6.0) 
 
 611.6 
 
 20(0-7) 
 
 22201796 
 20(1340-4190) 
 
 diamicton facies 
 (ms-d) 
 
 22.917.3 
 16(13-34) 
 
 40.618.0 
 16(25-51) 
 
 36.316.7 
 16(22-46) 
 
 18.9+20.1 
 16(0-40) 
 
 10.4H1.8 
 16(0-80) 
 
 19.518.2 
 16(3-33) 
 
 0.810.3 
 16(0.4-1.4) 
 
 2.313.6 
 16(0-12) 
 
 1623+599 
 16(830-2630) 
 
 Banner Formation 
 Uerte Clay 
 Member (W) 
 
 43 0113.0 
 14(13-60) 
 
 31.919.0 
 
 14(25-59) 
 
 25.1+6.4 
 14(15-42) 
 
 
 14(0) 
 
 
 14(0) 
 
 32.6H04 
 14(8-48) 
 
 09102 
 14(0.6-1.4) 
 
 5.113.0 
 
 14(0-9) 
 
 2574+71 1 
 14(1190-4040) 
 
 Casey till member 
 oxidized (bc-o) 
 
 21.817.0 
 24(10-40) 
 
 60.0±6.3 
 24(45-70) 
 
 18.215.2 
 24(10-30) 
 
 29.4115.5 
 21(4-63) 
 
 13.6+75 
 22(0-30) 
 
 243+7.3 
 8(15-32) 
 
 2.41-0.8 
 24(1.2-4 3) 
 
 1.311.1 
 
 6(0-3) 
 
 1583^240 
 8(1170-1790) 
 
 Casey till member 
 unoxidized (be) 
 
 8.3140 
 18(4-20) 
 
 62.814.7 
 18(56-70) 
 
 28 9138 
 
 18(22-36) 
 
 30.4H32 
 18(13-70) 
 
 13.415 9 
 18(7-34) 
 
 137+27 
 9(9-17) 
 
 15+0 3 
 18(1.1-1.9) 
 
 
 9(0-0) 
 
 16291538 
 9(1050-2730) 
 
M-120 
 CC-18 M-13 
 
 M-04 
 
 300