Red, brown, and white quartzose sandstone, and minor siltstone, shale and conglomerate
Mainly reddish-brown, medium- to fine-grained lithic arkosic sandstone, siltstone, and micaceous silty shale.
Lava flows, mostly basalt, andesite and felsite flows and subordinate interflow sedimentary rocks.
Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks
Red lithic conglomerate and sandstone; mafic to felsic volcanic flows similar to those of the unnamed formation (unit Yu) are interlayered with the sedimentary rocks.
Thick and stratigraphically varied formation of sedimentary and less abundant volcanic rocks. Metamorphosed graywacke is predominant rock of Michigamme Formation. Calcareous concretions common. Metamorphosed from cholorite to sillimanite grade (Cannon, 1986). Mapped undivided in poorly exposed areas
Porcupine Volcanics; Rhyolite
Gray, green, and brown lithic siltstone, shale, and sandstone. Copper sulfides and native copper occur locally near base
Dominantly dark-gray, massive, porphyritic tholeiitic basalt. Includes a basal conglomerate and a lean iron-formation in middle of formation
Dark-gray basalt and minor porphyritic andesite. Generally strongly magnetic with reversed remanent magnetism. Underlain by a thin unit of quartzose sandstone (Bessemer Quartzite).
Basaltic to andesitic volcanic flows interbedded within the conglomerate and sandstone
Portage Lake Volcanics; Rhyolite at Bergland
Gabbro, anorthosite, granite, peridotite
Gray, fine-grained, thin- to thick-bedded, commonly graded graywacke and slate in Marenisco, Mich. area