The Vermilion District in northeastern Minnesota contains one of the classic Neoarchean Archean granite-greenstone belt terranes in the United States that formed between 2722 Ma to ~2661 Ma. Crustal development during ...

Lower Paleozoic clastic strata of western Wisconsin were deposited during a series of transgressive marine incursions into the mid-continent in Cambrian to Ordovician time. These strata consist of intercalated sandstone, ...