Iron Mountain, an 8,007-foot summit in the San Gabriel Mountains of Los Angeles County, stands within Sheep Mountain Wilderness and reflects a layered naming history. Early miners in San Gabriel Canyon called it Sheep Mountain after the bighorn sheep that once roamed its slopes, but U.S. Geological Survey mapping in the 1890s adopted the name Iron Mountain instead; a 1940 U.S. Forest Service plan to restore the old name never took effect. The peak is also known as Iron Mountain #1 or Big Iron. Remote and seldom visited despite its proximity to Los Angeles, it is renowned as one of Southern California’s hardest climbs because of steep, trail-less, exposed terrain and the lack of water or facilities.