The Nigger Hill District, located on the Wyoming-South Dakota border in the northwestern Black Hills, is an area of Paleozoic sedimentaries, dipping outward from a central core of various alkaline and sub-alkaline Tertiary intrusive, and pre-Cambrian pegmatitic granite and schists. The Tertiary igneous rocks are of interest for three reasons: (1) they may furnish data that will contribute to the much debated problem of the origin of alkaline rocks; (2) when their structural relations are better understood, it will be possible to interpret more correctly the mechanics of their intrusion and the type of intrusive body they represent; (3) apparently they have been the source of the gold in a rare genetic type of potential ore deposit.
Proceedings of the Iowa Academy of Science
©1940 Iowa Academy of Science, Inc.
Berg, J. Robert
"Petrography of the Tertiary Igneous Rocks, Nigger Hill District, Wyoming-South Dakota,"
Proceedings of the Iowa Academy of Science, 47(1), 270-271.
Available at: https://scholarworks.uni.edu/pias/vol47/iss1/63