Elkhorn Mountains
| Elkhorn Mountains | |
|---|---|
West side of the Elkhorns as viewed from Jefferson County, Montana
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| Highest point | |
| Peak | Crow Peak |
| Elevation | 9,414 ft (2,869 m) |
| Coordinates | 46°17′38″N 111°54′15″W / 46.29389°N 111.90417°WCoordinates: 46°17′38″N 111°54′15″W / 46.29389°N 111.90417°W |
| Geography | |
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| Country | United States |
| State | Montana |
| Parent range | Rocky Mountains |
| Geology | |
| Age of rock | Late Cretaceous |
The Elkhorn Mountains are a mountain range in southwestern Montana, part of the Rocky Mountains and are roughly 300,000 acres (1200 km²) in size. It is an inactive volcanic mountain range with the highest point being Crow Peak at 9,414 ft (2,869 m), right next to Elkhorn Peak, 9,381 ft (2,859 m). The range is surrounded by the cities of Helena, Montana City, Townsend, Whitehall, and Boulder and is part of the Helena National Forest in Montana's Jefferson County.
The rocks of the Elkhorns were formed about 74 to 81 million years ago (Late Cretaceous time) as a result of the Farallon tectonic plate subducting beneath western North America and allowing magma to rise to the surface. The Elkhorn Mountains Volcanics are extrusive rocks related to the plutonic granites of the Boulder Batholith. Volcanic flows, lahars, and ash falls from sources in the Elkhorn Mountains reach as far as Choteau, Montana, but the thickest deposits lie within a radius of about 60 miles (97 km) from the Elkhorns. The volcanics probably originally covered an area of about 10,000 square miles (26,000 km2). Mineral deposits associated with the Elkhorn Mountains Volcanics include those mined at Elkhorn, Montana, now a ghost town, and gold at the Golden Sunlight Mine near Whitehall, which is associated with a breccia pipe in the volcanics.
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