2015 Map of Mount Day

About this map

Mount Day and the surrounding peaks of the Diablo Range dominate this 2015 survey of the borderlands between Alameda and Santa Clara counties. The landscape is characterized by a complex network of high ridges, including Beartrap Ridge, Valpe Ridge, and Oak Ridge, which partition the drainage basins of Alameda Cr and Arroyo Hondo. Small, high-altitude pockets of level ground such as Hamilton Flat and Van Horn Flats suggest historical points of human activity or grazing in an otherwise steep environment. The map details the transition from the watershed of Calaveras Cr toward the summit of Mt Lewis, illustrating how the terrain was divided by the Public Land Survey System. Modern infrastructure is sparse, limited primarily to Alum Rock Falls Rd and primitive tracks connecting the various peaks and remote flats.