"The surficial geology of McHenry County has been developed almost completely as a function of pre-Wisconsin and Wisconsin Episode glaciations, which specifically include ice marginal/subglacial and proglacial deposits (moraines/till and outwash, respectively)."
Learn more by clicking these links to the Illinois State Geological Survey's website:
Geologic Setting in McHenry County, Illinois
Surficial Geology of Wauconda Quadrangle Lake and McHenry Counties, Illinois