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Phosphate rock in the Three Forks-Yellowstone Park region, Montana: Chapter G in Contributions to economic geology (short papers and preliminary reports), 1927: Part I - Metals and nonmetals except fuels

Bulletin 795-G

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Abstract

The region described is about 7,000 square miles in area. It includes most of Gallatin and Madison Counties, in Montana, and some contiguous parts of Idaho and Wyoming. Within it are several broad fertile valleys and a number of prominent mountain ranges. A considerable part is underlain by a bed of phosphate rock which occurs in the Phosphoria formation, of Permian age, and is elevated to the surface of the mountainous area. In most of the middle and southwestern parts of the region this deposit is about 2 feet thick; locally it is 3 feet or more. Outcrops of beds in which the deposit is more than 6 inches thick aggregate more than 200 miles in length. Toward the northeast the deposit thins out, and its limit in that direction is represented fairly accurately by a line drawn from Yellowstone Park northwestward through Salesville to Willow Creek, on Jefferson Kiver. Its thicker parts contain 45 to 65 per cent of tricalcium phosphate.

In this region the phosphate deposit is thinner and of poorer quality than in the adjoining parts of Montana on the west and northwest, where it is commonly 4 feet thick and contains 65 to 70 per cent of tricalcium phosphate. In southeastern Idaho the deposit is still thicker and richer.

Study Area

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Phosphate rock in the Three Forks-Yellowstone Park region, Montana: Chapter G in Contributions to economic geology (short papers and preliminary reports), 1927: Part I - Metals and nonmetals except fuels
Series title:
Bulletin
Series number:
795
Chapter:
G
Year Published:
1927
Language:
English
Publisher:
Government Printing Office
Publisher location:
Washington, D.C.
Description:
iv, 63 p.
Larger Work Type:
Report
Larger Work Subtype:
USGS Numbered Series
Larger Work Title:
Contributions to economic geology (short papers and preliminary reports), 1927: Part I - Metals and nonmetals except fuels (Bulletin 795)
First page:
147
Last page:
209
Country:
United States
State:
Montana
Other Geospatial:
Three Forks-Yellowstone National Park Region