View from the top of Marble Mountain (elev. 6,881') in the Marble Mountain Wilderness west of Fort Jones, California. This particular section contains a vast region of marble karst (except for the summit block which is volcanized/metamorphized schist), 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. Black Marble Mountain is to the north, to the south one can see the snowy Trinity Alps, of Sierra Batholith origin. This peak is not formally named, though the entire rim leading up is collectively known as Marble Mountain.