Unconsolidated deposits, mainly glacial drift, overlie the bedrock surface in most of Illinois. Data are originally from ISGS Circular 490 by Piskin and Bergstrom (1975), Plate 1. Contour lines are coded with thickness, and polygons (areas between contours) are coded with range of thickness. ISGS, 1994 (revised 1998).
Publisher
Illinois Geospatial Data Clearinghouse
Access Rights
Public
Format
File
Language
English
Date Added
October 21, 2023
Provenance Statement
The metadata for this resource was last retrieved from ISGS on 2025-11-17.
[Creator not found] (n.d.). Glacial Drift Thickness and Character [Illinois]. Illinois Geospatial Data Clearinghouse. https://clearinghouse.isgs.illinois.edu/data/geology/glacial-drift-thickness-and-character (dataset)