The Marble Mountain Wilderness lies within the Klamath Mountains west of Fort Jones, California. This particular section b/w Black Marble Mountain & Marble Mountain contains a vast region of marble karst, w/ many channels & sinks of sculpted rock in solution leading down to vertical pits & cave entrances. There are at least 150 known cave entrances within the karst, the largest is Bigfoot Cave w/ about 12.4 miles of known passages & a depth of 1,205 feet, which is more than Oregon Caves to the north. The geology of the Klamath Mountains is among the most bizarre & intriguing in North America, nearby atop the marble & w/in are schist deposits & the adjacent higher peaks w/in the Boulder Peak region is comprised of red peridotite. To the south, one can see the snowy Trinity Alps, of Sierra Batholith origin. This view along the Marble Rim, which contains a long escarpment on the west side.