Bedrock Geology of Wisconsin, West-Central Sheet Types of bedrock, formation names, major faults, and time period of formation. Bedrock Geology Frac Sand Data and Resources M104 Bedrock Geology of Wisconsin, West-Central Sheet Brown, B.A.; 1988 Map: 28 in x 37 in, scale 1:250,000 Download ZIP M104-dataset01 M104 Dataset 1: GIS Data Brown, B.A.; 1988 GIS Data: GeMS file geodatabase and metadata Download Related Collections Map View Map