The Birchdale area lies near the southern edge of the Superior Province of the Canadian Shield. The rocks are felsic-intermediate metatuffs, metasediments, granite, and mafic intrusives. The rocks are part of a northwest ...

Early Proterozoic diabases in the Republic Mine, Northern Michigan have undergone pre-metamorphic hydrothermal alterations, followed by regional and retrograde metamorphism. High calcic plagioclase, pyroxene and olivine ...

The Barron Quartzite of northwestern Wisconsin is a fine-grained, quartz-cemented, buff to red quartz arenite with minor interbedded argillite and a thin basal quartz-pebble conglomerate. The thickness of the Barron is at ...

The geology of the Skinner Peaks 7 .5 minute quadrangle has been mapped at a scale of 1:24,000. The quadrangle is located m central Utah, just west of the leading edge of the Sevier fold-and-thrust belt, and in the transition ...

Lower Proterozoic rocks near Philbrook, Minnesota consist of tourmaline-rich metasedimentary rocks, ultramafic to mafic igneous rocks, and metaconglomerates. The metasedimentary rocks have been intersected by drilling only; ...