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.