A geological reconnaissance across the Bitterroot Range and Clearwater Mountains in Montana and Idaho

This report describes, in a preliminary way, a belt of country extending westward from the Bitterroot Valley, across the dividing range and the rugged mountains of the Clearwater system, down to the fertile plateaus which border the canyon of Snake River. It thus presents a reconnaissance section from western Montana across northern Idaho, and deals chiefly with areas about which, thus far, little geological information has been available.