|Elevation||5,240 ft (1,600 m)|
|Length||180 mi (290 km)north-south from Carquinez Strait to Polonio Pass|
|Width||20 mi (32 km)|
|Topo map||USGS San Benito Mountain|
The Diablo Range is a mountain range in the California Coast Ranges subdivision of the Pacific Coast Ranges in northern California, United States. It stretches from the eastern San Francisco Bay area at its northern end to the Salinas Valley area at its southern end.
The Diablo Range extends from the Carquinez Strait in the north to Orchard Peak and Polonio Pass in the south, near the point where State Route 46 crosses over the Coast Ranges at Cholame, as described by the United States Geological Survey (USGS). It is bordered on the northeast by the San Joaquin River, on the southeast by the San Joaquin Valley, on the southwest by the Salinas River, and on the northwest by the Santa Clara Valley.The USGS designation is somewhat ambiguous north of the Santa Clara Valley, but on USGS maps, the range is shown as the ridgeline which runs between its namesake Mount Diablo southeastward past Mount Hamilton. Geologically, the range corresponds to the California Coast Ranges east of the Calaveras Fault in this northern section. It is divided in two sections, the Eastern Diablo Range and the Western Diablo Range. The Eastern Diablo Range is located in the western Central Valley. The Westside Freeway runs parallel to it. The Western Diablo Range is found in the Central Coast and in the Bay Area. For much of its length, it is paralleled by other sections of the California Coast Ranges to the west, the Santa Cruz Mountains across the southern San Francisco Bay and Santa Clara Valley, and the Santa Lucia Range across the Salinas Valley.
The range passes through Contra Costa, Alameda, San Joaquin, Santa Clara, Stanislaus, Merced, San Benito, Fresno, Monterey, and Kings Counties, and ends in the northwesternmost extremity of Kern County.
Though the average elevation is about 3,000 feet (910 meters), a summit of over 2,300 feet (700 m) is considered high, mainly because the range is mostly rolling grassland and plateaus, punctuated by isolated peaks. Plateaus are usually at about 2,000–3,000 feet (610–910 m). Hills rise to about 1,000 feet (300 m), while foothills such those in the Santa Clara Valley, Livermore Valley and San Joaquin Valley are typically 400–1,000 feet (120–300 m).
Canyons are usually 300–400 feet (91–122 m) deep; valleys are often deeper but less steep-sided. Peaks often have high topographic prominence, as they are surrounded by valleys or lower hills or plateaus. Streams draining the eastern slopes of the Diablo Range include Hospital Creek and Ingram Creek. Stream draining the western slopes include Alameda Creek and Coyote Creek.
The Diablo Range's peaks and ridges are between 2,517–5,241 feet (767–1,597 m) and are distinct landmarks. Mount Diablo (3,849 feet (1,173 m)), San Benito Mountain (5,241 feet (1,597 m)), Mount Hamilton Ridge (4,230–4,260 feet (1,290–1,300 m)), and Mount Stakes (3,804 feet (1,159 m)) are four of the highest peaks in the range.
The Diablo Range is paralleled for much of its distance by U.S. Route 101 to the west and by I-5 to the east. Major routes of travel through the range include:
A sparsely used gravel road is the highest road in the range, with its highest point being on San Benito Mountain at over 5,000 feet.[ citation needed ]
The Diablo Range is largely unpopulated outside of the San Francisco Bay Area. Major nearby communities include Antioch, Concord, Walnut Creek, San Ramon, Pleasanton, Livermore, Fremont, Milpitas, San Jose, Morgan Hill, and Gilroy and the Central Valley city of Tracy. South of Pacheco Pass, the only major nearby communities (those with a population over 15,000) are Los Banos, and Hollister. The small town of Coalinga may also be notable for its location on State Route 198, one of the few routes through the mountains. Also the town of Kettleman City is also on State Route 41, another route that crosses the mountains. There are eight trans-Diablo routes that connect the Central Valley to the coast (four of them to the Bay Area).
Most of the range consists of private ranchland, limiting recreational use. However, the range does contain several areas of parkland, including Mount Diablo State Park, Alum Rock Park, Grant Ranch Park, Henry W. Coe State Park, Laguna Mountain Recreation Area, and the BLM's Clear Creek Management Area. In addition, some private land is held in conservation easements by the California Rangeland Trust.
Since the range lies around 10–50 miles (16–80 kilometers) inland from the ocean, and other coastal ranges like the Santa Lucia Range and the Santa Cruz Mountains block incoming moisture, the range gets little precipitation. In addition, the average elevation of 3,000 feet (910 m) is not high enough to catch most of the incoming moisture at higher altitudes.
Winters are mild with moderate rainfall, but summers are very dry and hot. Areas above 2,500 feet (762 m) get light to moderate snow in the winter, especially at the highest point, the 5,241 ft (1,597 m) San Benito Mountain in the remote southeastern section of the range. However, though sites at the lower end get annual snowfall, it is typically light and melts too fast to be noticed. Once or twice a decade there is seriously deep and long lasting snowfall.
Mercury contamination near the southern end of the range is an ongoing problem, due to the New Idria quicksilver mines, which stopped production in the 1970s. Heavy mercury contamination has been documented in the San Carlos and Silver Creeks, which flow into Panoche Creek, and thence into the San Joaquin River. This has resulted in mercury contamination all the way downstream to the San Francisco Bay. Silver and San Carlos creeks provide a wetland environment in an otherwise arid region and are important for the ecology of the region. As of 2011, New Idria has been listed as a Superfund site and scheduled for cleanup.
The Diablo Range is part of the California interior chaparral and woodlands ecoregion. It is covered mostly by chaparral and California oak woodland communities, with stands of closed-cone pine forests appearing above 4,000 feet (1,219 m). The native bunch grass savanna has been predominantly replaced by annual Mediterranean grasses, except in some rare habitat fragments. The understory is dominated with nonnative invasives. Blooming in spring are such plants as Viola pedunculata , Dodecatheon pulchellum , Fritillaria liliacea , and Ribes malvaceum , which can be viewed in the Blue Oak Ranch Reserve.
The range's riparian zones have such trees as bigleaf maple (Acer macrophyllum), white alder (Alnus rhombifolia), California bay (Umbellularia californica), and California sycamore (Platanus racemosa).
The most common trees are coast live oak (Quercus agrifolia) and blue oak (Quercus douglasii), with the largest blue oak growing in Alameda County. There are also good populations of California buckeye (Aesculus californica), and California black oak (Quercus kelloggii). The gray pine (Pinus sabiniana) and rarer Coulter pine (Pinus coulteri) can be found at all elevations, especially between 800–3,000 feet (240–910 m). Coulter pine reaches its northern limit on northern of Mt. Diablo. The conifers at higher elevations in the Diablo Range include knobcone pine (Pinus attenuata), Jeffrey pine (Pinus jeffreyi) and ponderosa pine (Pinus ponderosa).
The Diablo Range attracts far more raptors than coastal forests, such as red-tailed hawks. Golden eagle nesting sites are foundin the Diablo Range, reaching their highest density in southern Alameda County.
The Bay checkerspot butterfly, a federally listed threatened species, has habitat in the Range, especially at Mount Diablo. The California tiger salamander (Ambystoma californiense), also a federally threatened species and a vulnerable species of amphibian native to Northern California, lives in ponds in the range.The northern Pacific rattlesnake is thriving, as are many ground squirrels, hares, and various species of native and nonnative rodents.
Tule elk (Cervus canadensis ssp. nannodes) were restored to Mount Hamilton between 1978-1981 and are slowly recovering in several small herds in Santa Clara and Alameda Counties. See Mount Hamilton elk recovery. Black-tailed deer are abundant. Pronghorn, grizzly bears, and wolves were extirpated in the 1800s. There still are numerous coyotes and some of the more vital mountain lion populations in the state. There are excellent populations of bobcats and gray foxes, which depend on the chaparral habitat.
A species of millipede, Illacme plenipes , is endemic to the southern Diablo Range. First described in 1926, then not seen again until 2005, the species has more legs than any other species of millipede, with one specimen having 750.
Mount Diablo is a mountain of the Diablo Range, in Contra Costa County of the eastern San Francisco Bay Area in Northern California. It is south of Clayton and northeast of Danville. It is an isolated upthrust peak of 3,849 feet, visible from most of the San Francisco Bay Area. Mount Diablo appears from many angles to be a double pyramid and has many subsidiary peaks. The largest and closest is North Peak, the other half of the double pyramid, which is nearly as high in elevation at 3,557 feet (1,084 m), and is about one mile northeast of the main summit.
The San Gabriel Mountains are a mountain range located in northern Los Angeles County and western San Bernardino County, California, United States. The mountain range is part of the Transverse Ranges and lies between the Los Angeles Basin and the Mojave Desert, with Interstate 5 to the west and Interstate 15 to the east. The range lies in, and is surrounded by, the Angeles and San Bernardino National Forests, with the San Andreas Fault as its northern border.
The Sunol Regional Wilderness is a regional park in Alameda County, the eastern San Francisco Bay Area, Northern California. It is located near the town of Sunol, south of Pleasanton and east of Fremont.
The Tehachapi Mountains are a mountain range in the Transverse Ranges system of California in the Western United States. The range extends for approximately 40 miles (64 km) in southern Kern County and northwestern Los Angeles County and form part of the boundary between the San Joaquin Valley and the Mojave Desert.
Pacheco Pass, elevation 1,368 ft (417 m), is a low mountain pass located in the Diablo Range in southeastern Santa Clara County, California. It is the main route through the hills separating the Santa Clara Valley and the Central Valley.
The State Scenic Highway System in the U.S. state of California is a list of highways, mainly state highways, that have been designated by the California Department of Transportation (Caltrans) as scenic highways. They are marked by the state flower, a California poppy, inside either a rectangle for state-maintained highways or a pentagon for county highways.
Henry W. Coe State Park is a state park of California, United States, preserving a vast tract of the Diablo Range. The park is located closest to the city of Morgan Hill, and is located in both Santa Clara and Stanislaus counties. The park contains over 87,000 acres (35,000 ha), making it the largest state park in northern California, and the second-largest in the state. Managed within its boundaries is a designated wilderness area of about 22,000 acres (8,900 ha). This is officially known as the Henry W. Coe State Wilderness, but locally as the Orestimba Wilderness. The 89,164-acre (36,083 ha) park was established in 1959.
Mount Hamilton is a mountain in the Diablo Range in Santa Clara County, California. The mountain's peak, at 4,265 feet (1,300 m), overlooks the heavily urbanized Santa Clara Valley and is the site of Lick Observatory, the world's first permanently occupied mountain-top observatory. The asteroid 452 Hamiltonia, discovered in 1899, is named after the mountain. Golden eagle nesting sites are found on the slopes of Mount Hamilton. On clear days, Mount Tamalpais, the Santa Cruz Mountains, Monterey Bay, the Monterey Peninsula, and even Yosemite National Park are visible from the summit of the mountain.
The South Bay Aqueduct is an aqueduct located in the eastern part of the San Francisco Bay Area. It conveys water from the Sacramento-San Joaquin Delta through over forty miles of pipelines and canals. It begins in north-eastern Alameda County on the California Aqueduct's Bethany Reservoir serving as the forebay. The aqueduct flows along the eastern and southern edges of the Livermore Valley. Then it flows through a series of tunnels to an end in the foothills of eastern San Jose, 5 miles (8 km) from downtown San Jose, California.
The Coast Ranges of California span 400 miles (644 km) from Del Norte or Humboldt County, California, south to Santa Barbara County. The other three coastal California mountain ranges are the Transverse Ranges, Peninsular Ranges and the Klamath Mountains.
The community of San Antonio Valley, also called San Antonio or San Antone, is located along the Diablo Range in eastern Santa Clara County, California. The locale is bordered by Alameda County to the north and Stanislaus County to the east. The sparsely populated area is located at the junction of San Antonio Valley Road, Mines Road, and Del Puerto Canyon Road. The area includes the San Antonio Valley Ecological Reserve, a 3,282 acre nature preserve created by a Nature Conservancy purchase of land from local rancher, Keith Hurner, and known for its herd of tule elk.
California oak woodland is a plant community found throughout the California chaparral and woodlands ecoregion of California in the United States and northwestern Baja California in Mexico. Oak woodland is widespread at lower elevations in coastal California; in interior valleys of the Coast Ranges, Transverse Ranges and Peninsular Ranges; and in a ring around the California Central Valley grasslands. The dominant trees are oaks, interspersed with other broadleaf and coniferous trees, with an understory of grasses, herbs, geophytes, and California native plants.
Cirsium fontinale, the fountain thistle, is a flowering perennial herb in the sunflower family. It is endemic to California. The genus Cirsium is commonly known as the "thistle" genus, Cirsium being the Greek word for 'thistle.'
Carbonera Creek is a 10.2-mile-long (16.4 km) watercourse in Santa Cruz County, California, that eventually flows to the San Lorenzo River.
Grant Ranch Park is the largest county park in Santa Clara County, California. Also known as Joseph D. Grant County Park, this site is situated in the Diablo Range foothills of the eastern Santa Clara Valley. The park is one of 28 owned by Santa Clara County and managed by the Santa Clara County Parks and Recreation Department.
Smith Creek is a 14-mile-long (23 km) perennial stream which flows along the western flank of Mount Hamilton in Santa Clara County. The creek begins near Bollinger Ridge, about 7.7 km SxSW of Mount Hamilton.
Santa Clara County, officially the County of Santa Clara, is California's 6th most populous county, with a population of 1,936,259, as of the 2020 census. Santa Clara County and neighboring San Benito County together form the U.S. Census Bureau's San Jose-Sunnyvale-Santa Clara, CA Metropolitan Statistical Area, which is part of the larger San Jose-San Francisco-Oakland, CA Combined Statistical Area. Santa Clara is the most populous county in the San Francisco Bay Area and in Northern California.
El Camino Viejo a Los Ángeles, also known as El Camino Viejo and the Old Los Angeles Trail, was the oldest north-south trail in the interior of Spanish colonial Las Californias (1769–1822) and Mexican Alta California (1822–1848), present day California. It became a well established inland route, and an alternative to the coastal El Camino Real trail used since the 1770s in the period.