The Early Proterozoic Penokean Orogen developed along the southern margin of the Archean Superior craton. The orogen consists of a northern deformed continental margin prism overlying an Archean basement and a southern assemblage of oceanic arcs, the Wisconsin magmatic terranes. The south-dipping Niagara fault (suture) zone separates the south-facing continental margin from the accreted arc terranes. The suture zone contains a dismembered ophiolite. The Wisconsin magmatic terranes consist of two terranes that are distinguished on the basis of lithology and structure; the northern Pembine-Wausau terrane and the southern Marshfield terrane. -from Authors