Metalliferous deposits of the greater Helena mining region, Montana
<p>The ore deposits described in this bulletin are distributed through a region of about 3,000 square miles surrounding the city of Helena, Mont. In general…
Public-domain full text preserved in the Mountain Man Mining Library. Original source: pubs.usgs.gov.
Metalliferous deposits of the greater Helena mining region, Montana Author: Pardee, Joseph Thomas, Schrader, F. C. Year: 1933 Category: Report ore deposits described in this bulletin are distributed through a region of about 3,000 square miles surrounding the city of Helena, Mont. In general the surface of this region is mountainous, but it includes several large intermontane valleys. Large areas in the northern and eastern parts of the region sire underlain by sedimentary rocks of the Algonkian Belt series, and on the northeast and southwest the Belt rocks are overlain without any noticeable angular unconformity by Paleozoic and Mesozoic beds. Oligocene, Miocene, and possibly Pliocene sediments, composed chiefly of volcanic a Tags: usgs, Helena Montana gold mining Source: https://pubs.usgs.gov/bul/0842/plate-15.pdf