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Reconnaissance geologic map of the Sliderock Mountain area, Sweet Grass and Stillwater counties, Montana

Miscellaneous Field Studies Map 2259

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Abstract

The remains of a deeply eroded Late Cretaceous stratovolcano centered near Sliderock Mountain dominate the map area. The volcano consists mostly of lahars, although basaltic andesite lava flows are also present. An extensively eroded, weakly mineralized hypabyssal intrusive complex, inferred to represent the volcano's solidified magma chamber, intrudes previously erupted lava flows and associated lahars. Cretaceous sandstone and shale and Paleozoic sedimentary rocks, principally limestone of the Madison Group, host the stratovolcano; remnants of these rocks are preserved as large xenoliths and roof pendants.

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Reconnaissance geologic map of the Sliderock Mountain area, Sweet Grass and Stillwater counties, Montana
Series title:
Miscellaneous Field Studies Map
Series number:
2259
Edition:
-
Year Published:
1994
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Description:
Map: 31.37 x 33 inches
Country:
United States
State:
Montana
County:
Stillwater County;Sweet Grass County
Other Geospatial:
Sliderock Mountain
Scale:
50000