Michigan Dept. of Environment, Great Lakes, and EnergyBedrock geology : digitized from the 1987 Michigan Bedrock Geology map from the Michigan Geological Survey; Milstein, Randall, 1987, Bedrock Geology of Southern Michigan: Michigan Department of Natural Resources, Michigan Geological Survey, Geological Publication BG-01, scale 1:500,000. Reed, Robert C., and Daniels, Jennifer, 1987, Bedrock Geology of Northern Michigan: Michigan Department of Natural Resources, Michigan Geological Survey, Geological Publication BG-01, scale 1:500,000. Midcontinent Rift: Areas underlain by rifting in the midcontinent approximately 1.1 billion years ago. John Esch, 2011, unpublished map. For more information, visit Michigan.gov/EGLE/Maps-Data/GeoWebFace or contact EGLE-GeoWebFace@michigan.gov . Field Name Field Descriptions OBJECTID ESRI ID Number FormationCode Formation code FormationName Formation nameArcGIS DynamicMapLayerhttps://hub.arcgis.com/datasets/74d201ffb0874870a090e0217845a6ec_0engState of Michigan Open Data PortalPublicMichigan Bedrock Geology [Michigan]Web servicesMichiganLast Modified: 2025-09-24