Site information:

Mount Diablo State Park, on summit

Access limited to State Park operating hours.

37.881733,-121.9144

Plaque information:

State plaque

Plaque text:

Mount Diablo

Mount Diablo, sacred to Native Americans who lived and worshipped there for over 5,000 years became a critical reference point for Spanish explorers in the 18th century, and American trappers and early California settlers in the 19th. In 1851 Colonel Leander Ransome established the crossing of the Mount Diablo Base and meridian lines from which most of California and Nevada are surveyed.

Plaque placed by the State Department of Parks and Recreation in cooperation with the San Ramon Valley Historical Society, April 23, 1978.

OHP description:

Mount Diablo had been a home with spiritual significance to the Costanoan Indians for at least 500 years when Spanish explorers viewed the mountain in 1772. In 1851 Mount Diablo was selected as the initial point for land surveys of Northern California and Nevada, with the Mount Diablo Base and Meridian Lines originating at its peak. Due to the mountain's variations in wind, rainfall, and temperature, it is also a preserve for a wide variety of plant and animal life.

Registered 12/7/1976