Black Marsh
An isolated upthrust peak serving as the primary survey datum for Northern California.
Mount Diablo is an isolated upthrust peak rising 3,849 feet (1,173 meters) in Contra Costa County, situated south of Clayton and northeast of Danville within the eastern San Francisco Bay Area. Part of the Diablo Range, this prominent landmark appears from many angles as a double pyramid featuring subsidiary peaks, most notably North Peak. Visible from most of the Bay Area, it stands as a critical reference point for land surveying across much of northern California and Nevada.
- Elevation
- 3,849 feet (1,173 meters)
- Location
- Contra Costa County, Eastern San Francisco Bay Area
- North Peak Elevation
- 3,557 feet (1,084 m)
- Distance to Lassen Peak
- 181 miles (291 kilometers)
- State Park Size (as of 2007)
- almost 20,000 acres (8,100 ha)
- Total Protected Lands
- more than 90,000 acres (36,000 ha)
Verified Timeline
Lore & Background
For many California Native American peoples, Mount Diablo is sacred. Miwok and Ohlone mythologies describe it as a point of creation; in one narrative fragment, the mountain and Reed's Peak (Mount Tamalpais) were islands surrounded by water where creator Coyote and assistant Eagle-man made people. Another story tells of Molok the Condor bringing forth his grandson Wek-Wek from within the mountain. About 25 independent tribal groups lived nearby at European contact, speaking Ohlone, Bay Miwok, and Northern Valley Yokuts dialects. The Chochenyo-speaking Ohlone called it Tuyshtak, meaning "at the dawn of time," while the Nisenan named it Sukkú Jaman ("dog mountain"). Spanish colonists referred to it as Cerro Alto de los Bolbones by 1811. The current name stems from a 1805 incident where Spanish soldiers interpreted a mysterious dancing spirit, or "puy," as a devil during the escape of Chupcan natives.
In Their Own Story
By 1824, the region north of the mountain was known as Monte del Diablo ("devil's thicket"), shown on maps near present-day Concord. In May 1862, William H. Brewer named the northeast peak "Mount King" after Rev. Thomas Starr King; it is now known as North Peak. Surveying history began in 1851 when Colonel Leander Ransom selected the south peak as the initial point for Mount Diablo Base and Meridian lines. Toll roads opened in 1874 by Joseph Seavey Hall and William Camron, with Hall's road opening May 2 of that year. Hall also built the 16-room Mountain House Hotel near the road junction, which burned around 1901. In 1928, Standard Oil erected the "Eye of Diablo" beacon at the summit. From 1954 to 1957, the peak hosted broadcasts for KSBR-FM and KOVR.
Reader's Guide
The summit is accessible by foot, bicycle, or motor vehicle via North Gate Road or South Gate Road. On a clear day, the Sierra Nevada range is plainly visible, with Lassen Peak (181 miles away) occasionally just visible over the curve of the earth. Sentinel Dome in Yosemite National Park can be seen, though Half Dome is hidden by an 8,000-foot ridge. Eight bridges are visible from southwest to northeast: San Mateo, Bay, Golden Gate, San Rafael, Carquinez, Benicia, Antioch, and Rio Vista. The mountain sits within Mount Diablo State Park, which was first established around the peak in 1931 after initial legislation in 1921. Botanist Mary Leolin Bowerman published her study boundaries in 1936, forming the basis for the park's first map. As of December 2007, the state park totaled almost 20,000 acres (8,100 ha), while protected lands on and around the mountain exceeded 90,000 acres across 38 preserves.
Did You Know?
- Mount Diablo serves as the reference datum for land surveying in much of northern California and Nevada.
- The name 'Kahwookum' was made up in 1866 with no real Native American connection, later resurfacing as a 1916 real estate gimmick.
- An aerial navigation beacon known as the 'Eye of Diablo' was visible for a hundred miles when erected by Standard Oil in 1928.
- On clear days, eight bridges are visible from the summit, ranging from San Mateo to Rio Vista.
- Botanist Mary Leolin Bowerman's 1936 dissertation boundaries became the basis for Mount Diablo State Park's first map.