3-D MAPPING OF THE QUATERNARY GLACIAL DEPOSITS IN THE HEBRON QUADRANGLE, McHenry COUNTY, ILLINOIS

The sand and gravel deposits in the Hebron Quadrangle, McHenry County, Illinois represent the outwash deposits of multiple glaciations which intertounge with the glacial till deposits. These sand and gravel units are the sole source of water within the Hebron Quadrangle. There is a need to better understand their distribution, geometry, and hydrologic properties in the interest of groundwater supply. Stratigraphic borings, 1-D and 2-D geophysical data, and historical water well records were collected and reviewed. These data were imported into Petrel 2007 to generate 3-D surfaces that delineate horizons representing the top elevations of Wisconsin and Illinois Episode glacial deposits. Products indicate variability of the sand and gravel bodies within the Hebron Quadrangle, such as thickness and extent of those aquifers, and an estimation of the hydrologic properties within those sand and gravel units. The 3-D products as well as new stratigraphic borings have contributed to an increased understanding of the local and regional geology as well as an increased knowledge of the geologic events associated with glacial retreat. Ultimately, the 3-D surfaces will provide the basis for groundwater flow modeling, capable of estimating future groundwater resources for the Hebron Quadrangle.