The principal geologic structures present are granitic and metamorphic rock formations. Located approximately west of Colfax is a branch of the Melones Fault, running in north to south direction. The fault runs through the old grammar school baseball field so they closed the school. (Earth Metrics, 1989) Another branch of the same fault is located about to the east, also aligned in a north–south orientation. No movement has been recorded by the U.S. Geological Survey, and the faults are considered inactive. Bunch Creek is an active water source flowing south to eventually reach a confluence with the North Fork of the American River.