Geology of the Three Forks quadrangle, Montana, with sections on petrography of igneous rocks
Professional Paper
370
By: G. D. Robinson and Henry Frank Barnett
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- Document: Report
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Abstract
The Three Forks quadrangle at the head of the Missouri River, has a long stratigraphic succession. The oldest rocks are Precambrian gneiss, derived from arkosic sandstone, and amphibolite, probably altered from mafic sills and lava flows. The unmetamorphosed sedimentary rocks range in age from late Precambrian to Recent, have an aggregate thickness of about 11,000 feet, and underlie about 85 percent of the quadrangle. The only systems not represented are Ordovician,
Silurian, and Triassic.
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Geology of the Three Forks quadrangle, Montana, with sections on petrography of igneous rocks |
| Series title | Professional Paper |
| Series number | 370 |
| DOI | 10.3133/pp370 |
| Year Published | 1963 |
| Language | English |
| Publisher | United States Government Printing Office |
| Description | iv, 143 p. |
| Country | United States |
| State | Montana |
| Other Geospatial | Three Forks quadrangle |