Description: “c(fp)”#”Silt and clay; occasional sand lenses; trace gravel; stratified; brown to yellowish brown; loose to compact; may be mottled and gleyed; some bedding; organic-rich in places; Typical thickness: 1 to 20 feetdg#"Fill, excavated land, or other disturbed material; highly variable in grain size (may range from clay to gravel) and color; may contain construction and mining debris; Typical thickness: variable"“e”#"Silt and clay; may be massive, bedded or laminated; dark gray to light gray; calcareous; soft to hard; compact; may be sticky and plastic; very fine and fine sand common along bedding planes; occasional inclusions and lenses of light gray to white silt; some wood fragments; very few clasts; generally abrupt upper and lower contacts. Typical thickness: 5 to 25 feet"“gp”#"Peat, muck, and organic-rich sediment; may contain interbeds of silt, clay and some fine sand; black to dark brown; soft to firm; snail shells common. Typical thickness: 1 to 10 feet"“h(f)”#"Sand; fine to medium, massive to stratified, lenses of silt common; yellowish brown to gray; Typical thickness: 5 to 30 feet"“h(m)”#"Sand and gravel; stratified; occasionally massive; yellowish to grayish brown; calcareous; loose; sand is very fine to very coarse, very well to poorly sorted; gravel is very fine to coarse, very well to very poorly sorted; trace to little amounts of silt and clay, frequently as thin beds. Typical thickness: 5 to 120 feet"“h(p)”#"Sand; fine and medium; well sorted; loose; may be mixed with organics, including layers of peat; some thin lenses of clay; Typical thickness: 1 to 12 feet"“h(p)gp”#"Sand and peat, muck, marl, and organic-rich sediment; intermixed dune sand and peat in back dune area; fine and medium sand with trace silt and clay; peat and silt and clay content increases in lower-lying areas; stratified; Typical thickness 1 to 12 feet"“l-h”#"Diamicton; commonly very cobbly sandy loam to silty loam but quite variable; beds of sand, silt, and clay; yellowish brown to brown; calcareous; hard. Typical thickness: 10 to 50 feet"“t”#"Diamicton; pebbly loam to clay loam; light reddish brown to brown; hard; dense; calcareous; some cobbles and boulders; contains discontinuous beds of stratified sand, silt, or clay. Typical thickness: 5 to 45 feet(thickens to west in McHenry County)"“w”#"Diamicton; silty clay loam to silty clay; dark gray to yellowish brown; massive; calcareous; compact; firm to very hard; pebbly with occasional cobbles and boulders; commonly contains silt and sand inclusions and sand and/or gravel lenses; may contain pebble-free, silty and clayey zones with strongly expressed laminations that may be interbedded with the diamicton; lenses of saturated silt and very fine sand are loose and liquify in core; Typical thickness: 50 to 200 feet"“h”#Sand and gravel; fine to coarse; often well stratified; yellowish brown to brown; may contain some silt and clay lenses; Typical thickness: 5 to 30 feet “dg/h”#"Fill, excavated land, or other disturbed material; highly variable in grain size (may range from clay to gravel) and color; may contain construction and mining debris; Typical thickness: variable/Sand and gravel; fine to coarse; often well stratified; yellowish brown to brown; may contain some silt and clay lenses; Typical thickness: 5 to 30 feet "“dg/e”#"Fill, excavated land, or other disturbed material; highly variable in grain size (may range from clay to gravel) and color; may contain construction and mining debris; Typical thickness: variable/Silt and clay; may be massive, bedded or laminated; dark gray to light gray; calcareous; soft to hard; compact; may be sticky and plastic; very fine and fine sand common along bedding planes; occasional inclusions and lenses of light gray to white silt; some wood fragments; very few clasts; generally abrupt upper and lower contacts. Typical thickness: 5 to 25 feet"“dg/w”#"Fill, excavated land, or other disturbed material; highly variable in grain size (may range from clay to gravel) and color; may contain construction and mining debris; Typical thickness: variable/Diamicton; silty clay loam to silty clay; dark gray to yellowish brown; massive; calcareous; compact; firm to very hard; pebbly with occasional cobbles and boulders; commonly contains silt and sand inclusions and sand and/or gravel lenses; may contain pebble-free, silty and clayey zones with strongly expressed laminations that may be interbedded with the diamicton; lenses of saturated silt and very fine sand are loose and liquify in core; Typical thickness: 50 to 200 feet"water#“e(x)”#"Clay, silt, sand, and diamicton; continuity, thickness, and composition variable; generally stratified; poorly to well sorted; dark gray to yellowish brown; calcareous; gradational to abrupt contacts; Typical thickness: 5 to 50 feet, varies with relief of landform"
Copyright Text: Illinois State Geological Survey
Prairie Research Institute
University of Illinois at Urbana-Champaign
615 East Peabody Drive
Champaign, Illinios 61820
217-333-4747 general
isgs@isgs.illinois.edu general email address www.isgs.illinois.edu
This map was funded by: 1.) the State of Illinois; and 2.) the U.S. Geological Survey (STATEMAP and Great Lakes Geologic Mapping Coalition components of the National Cooperative Geologic Mapping Program) under Cooperative Agreements 00HQAG0151, 01HQAG0103, 03HQAG0112, 04HQAG0046, 05HQAG0079, 06HQAG0053, 07HQAG019, 08HQAG0084, G09AC00197, G09AC00503, G10AC00418, G10AC00706, G12AC20291, and G13AC00168.