Exposed Precambrian Bedrock in Part of Dickinson County, Michigan, and Marinette and Florence Counties, Wisconsin

The U.S. Geological Survey conducted a program of bedrock geologic mapping in much of the central and western upper peninsula of Michigan and parts of Wisconsin from...美国地质调查局（U.S. Geological Survey）在密歇根州上半岛中西部大部分区域以及威斯康星州部分区域，开展了一项基岩地质填图（bedrock geologic mapping）项目，该项目始于……