Timber Mountain is a peak in Southern California’s San Gabriel Mountains, in the Cucamonga Wilderness of Angeles National Forest, above the Icehouse Canyon area. Though sometimes shown as a hill, it is identified as a mountain peak in rugged high country. Originally called Chapman Mountain, it was renamed Timber Mountain in the mid-20th century. Hikers commonly reach it by the Three T’s Trail, which connects nearby summits across exposed alpine-like terrain unusual for this part of Southern California. Routes approach from the south through Icehouse Canyon and Icehouse Saddle or from the north by way of Telegraph Peak and Thunder Mountain.