Marked by cliffs, pinnacles, canyons. Remaining material is a light colored Precambrian granite with gneiss, quartzite, greenstone, and schism.
Principal hazards are landslides and erosion.
Runoff from snowbelt, thunderstorms and from springs fed by ground water. Little water use in area. Important source of water used elsewhere. Upper Sonoran foothills to Transition, Canadian, and Hudsonian on peaks. Vegetation is somewhat sensitive to over browsing and intrusion by man.