Paleontology and geology

Sea level rose during this time, and by the Late Cambrian much of southern Minnesota was flooded. The slow rise of the sea left behind records of a sandy coastline dominated by tropical storms. Wind blown sand dunes accumulated on land. The sediments that were deposited in the warm, shallow sea were mostly sandy, and contain a record of life dominated by trilobites, brachiopods, and strange, shelled organisms called hyoliths.