Structural Features in Illinois: Point Locations of Impact Features, Explosion Features, Silurian Reefs, and Buried Precambrian Hills

These data are for use at a scale of 1:500,000 or smaller only. They are appropriate for use in regional thematic analysis, for display purposes, and for mapping environmental phenomena related to them. This is a partial representation of Plate 1 from ISGS Bulletin 100 (1993). Features depicted are limited to well documented, significant ` impact features, explosion features, Silurian reefs, and buried Precambrian hills in Illinois. Names of the features are indicated. This data set must be used in conjunction with the companion data sets STRUCTFAULTS, STRUCTCLINES and STRUCTPOLY for a full representation of Plate 1 of ISGS Bulletin 100.