View from the top of Black Marble Mountain (elev. 7,442') 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.  To the south, one can see the snowy Trinity Alps, of Sierra Batholith origin.  The Red Buttes Wilderness & Siskiyou Mountains are visible to the north, as is Grayback Mountain, Preston Peak, & the edges of Mt. McLoughlin & Mt. Shasta.