Quaternary Deposits of Illinois, 1979, GeMS 2021 version
This dataset conforms to GeMS (Geologic Map Schema)--a standard format for the digital publication of geologic maps, available at https://ngmdb.usgs.gov/Info/standards/GeMS/. The intention of the 2021 project which produced this dataset was to digitally archive the original Lineback 1979 map in the U.S. Geological Survey Geologic Map Schema (GeMS). More information on the history of this dataset can be read in the Process Steps of this metadata. Eight Chicago area counties include data which may reflect the Willman and Lineback 1970 map instead of Lineback 1979. Outside of those eight counties this dataset matches Lineback 1979.
Zip Data: ILQuatDeposits1979_GeMS.zip(121 MB)
Quaternary Deposits of Illinois, 1979, digitized 1984
This dataset is an early, but highly generalized, version of the Lineback (1979) map was digitized by Esri in 1984.The original coverage was generated in 1984 by Esri as one component of a multi-layer Integrated Terrain Unit (ITU) database. Attribute accuracy was subsequently reviewed by ISGS personnel. Details of this review are unavailable.Polygons on the source map of less than one square mile in area or less than one half mile in width are not included. Other narrow polygons shown on the source map are not reflected in the data set, possibly due to polygon collapse. As a result, overlay with the published map shows significant differences in some areas. This data can only be used to show the generalized Quaternary boundaries within Illinois.
Zip Data: IL_Quat_Geology_500K_1979_Py.zip(2.91 MB)