Prairie du Chien Group

The Prairie du Chien Group is a sequence of ancient sedimentary rock layers formed during the Paleozoic Era, approximately 350 to 500 million years ago. These rocks mainly consist of limestone, dolomite, shale, and sandstone, and they were deposited in shallow seas that covered parts of what is now the Midwest United States. The Prairie du Chien Group is significant geologically because it contains important fossils and mineral deposits, and it helps scientists understand Earth's early marine environments and geological history of the region.