GIF images are not cartographic products; they portray the general nature of the data.
Bedrock Geology, 2005
Bedrock Geology, 1967
Distribution and extent of the bedrock geologic units within Illinois. Data originally from the Geologic Map of Illinois (1967) by Willman and et. al.. Depicts geologic units and fault lines. Attributes include geologic unit and fault designation. ISGS, 1996.
Topography of the bedrock surface in Illinois. Bedrock topography is shown as 50-foot (15-meter) contours of bedrock elevation above mean sea level (msl). Several major bedrock valleys are found across the state. Attributes include contour values. ISGS, 1994.
Continuous lines representing the lowermost elevations/ locations of (buried) bedrock valleys in the state of Illinois. Names of buried valleys are annotated. Attributes include bedrock valley names. ISGS, 1994.
Location Points from the ISGS Wells and Borings Database
This shapefile contains point locations from the ISGS Wells and Borings database. The attribute information include API number (the ID), well or boring type, longitude, and latitude. The spatial reference is geographic coordinates, decimal degrees, NAD83. The data are exported to a shapefile weekly from the Wells and Borings (source) database for Internet distribution. ISGS, 2008.
Structural Features: Anticlines, Synclines, and Monoclines
Structural features, anticlines, synclines, and monoclines in Illinois. Features depicted are limited to significant anticlines, synclines and monoclines. Names of the features and the geologic horizons (bedrock unit) on which they were mapped are included. Use in conjunction with companion data sets structfaults, structpnts and structpoly for a full representation of Plate 1 of ISGS Bulletin 100 (1993). ISGS, 1995.
Structural Features: Faults, Grabens, and Flexures
Structural features, significant faults, faulted flexures and grabens in Illinois. Names of the features and the associated directions of faulting are included. Use in conjunction with companion data sets structclines, structpnts and structpoly for a full representation of Plate 1 of ISGS Bulletin 100 (1993). ISGS, 1995.
Structural Features: Polygon and Point Features
Structural features depicted are limited to well documented, significant anticlines and domes (and the Glasford Disturbance), impact features, explosion features, Silurian reefs, and buried Precambrian hills in Illinois. Names of the features are indicated. Use in conjunction with companion data sets structclines, structfaults, and structpoly for a full representation of Plate 1 of ISGS Bulletin 100 (1993). ISGS, 1995.