Elkhorn Mountains

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.

The mountain range seen today is related to regional structural uplift dating mostly to Oligocene time.

Recently with efforts conducted by the BLM, Montana FWP and Helena National Forest, new conservation and wildlife management plans have been put into place including big horn sheep reintroduction and the westslope cutthroat trout restoration program.

Management of the 2000+ elk herd in the area and the suppression of noxious weeds is also an ongoing task.

Late Cretaceous paleogeographic map of the United States, showing Elkhorn volcanoes in the northwest
South face of the Elkhorns as seen from outside Boulder, Montana .