- GeoRef, Copyright 2008, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
The Pine River quartzite conglomerate and Keys Lake quartzite, low-grade metamorphic rocks, and informal members of the Michigamme Slate are highly quartzitic units deposited, presumably, in a eugeosyncline tectonic environment. Sedimentary structure orientations and mineral composition of the rocks of the two units suggest a southeastward sediment movement and derivation from similar sedimentary rock sources to the northwest. Composition and texture suggest deposition in shallow-water marine environment close to source areas. Associated 'graywackes' are highly quartzose.