Geology
The center of the range is occupied by the Tobacco Root Batholith, thought to be a satellite pluton of the Boulder Batholith. This Late Cretaceous granitic body intrudes Archean gneisses and schists. Significant gold deposits appear to be related to the intrusion of the Tobacco Root Batholith and northwest-trending faults in the Pony area and elsewhere. The northern flank of the Tobacco Roots consists of thrusted and folded sedimentary and volcaniclastic rocks ranging from Proterozoic Belt Supergroup strata to Cretaceous Elkhorn Mountains Volcanics. Thick sections of Paleozoic and Mesozoic strata, including the Flathead Sandstone and Madison Limestone, are present.
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