Diablo Range

For the census county division, seeDiablo Range (census county division).

TheDiablo Rangeis amountain rangein theCalifornia Coast Rangessubdivision of thePacific Coast Rangesin northernCalifornia,United States. It stretches from the easternSan Francisco Bay Areaat its northern end to theSalinas Valleyarea at its southern end.

Diablo Range
Mount Hamilton
Highest point
Elevation	5,240 ft (1,600 m)
Dimensions
Length	180 mi (290 km) north-south fromCarquinez StraittoPolonio Pass
Width	20 mi (32 km)
Geography
Diablo Range Location of the Diablo Mountain Range inCalifornia,U.S.
Country	United States
State	California
Region	Central California
Range coordinates	36°22′10.844″N120°38′39.609″W
Topo map	USGSSan Benito Mountain

Geography

The Diablo Range extends from theCarquinez Straitin the north to Orchard Peak andPolonio Passin the south, near the point whereState Route 46crosses over the Coast Ranges atCholame,as described by theUnited States Geological Survey(USGS). It is bordered on the northeast by theSan Joaquin River,on the southeast by theSan Joaquin Valley,on the southwest by theSalinas River,and on the northwest by theSanta Clara ValleyandSan Francisco Bay.On USGS maps, the "Diablo Range" is shown as the ridgeline which runs between its namesakeMount Diablosoutheastward pastMount Hamilton.However, the USGS Geographic Names Information System (GNIS) includes theEast Bay Hillsin its list of various GPS coordinates for the Diablo Range. Although not formally recognized by USGS GNIS, the East Bay Hills consists of theBriones Hillsfurthest north, then theBerkeley Hills,theSan Leandro Hillscentrally, and Walpert RidgeandPleasanton Ridgeto the southwest and southeast, culminating atAlameda Creek/Highway 84.

Geologically, the Diablo Range corresponds to the California Coast Ranges east of theCalaveras Faultin its northern section. For much of its length, it is paralleled by other sections of the California Coast Ranges to the west, theSanta Cruz Mountainsacross the southern San Francisco Bay and Santa Clara Valley, and theSanta Lucia Rangeacross theSalinas Valley.The East Bay Hills are bounded geologically by the Calaveras Fault to the east and theHayward Faultto the west.

The range passes throughContra Costa,Alameda,San Joaquin,Santa Clara,Stanislaus,Merced,San Benito,Fresno,Monterey,andKingsCounties, and ends in the northwesternmost extremity ofKern County.

Topography

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 includeHospital CreekandIngram Creek.Stream draining the western slopes includeAlameda CreekandCoyote Creek.

Peaks

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)), andMount Stakes(3,804 feet (1,159 m)) are four of the highest peaks in the range.

View of Mt. Diablo fromConcord.Main peak at right, North Peak at left, Mt. Zion at center (scroll image L/R to view)

Human elements

The south edge (mostly Monument Peak) of the Mission Ridge as seen fromMilpitas.

The Diablo Range is paralleled for much of its distance byU.S. Route 101to the west and byI-5to the east. Major routes of travel through the range include:

• North of the range
  • BNSF Railway/Amtrak San Joaquin
• Willow Pass
  • State Route 4
  • BARTYellow Line
• Altamont Pass
  • Union Pacific Railroad/Altamont Corridor Express
  • I-580
• Sunol Valley
  • State Route 84
  • I-680
• Patterson Pass
• Corral Hollow Pass
• Mount Hamilton
  • State Route 130
• Pacheco Pass
  • State Route 152
  • FutureCalifornia High-Speed Rail
• Panoche Pass
• State Route 198
• Cottonwood Pass (State Route 41)
• Polonio Pass(State Route 46)

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.

The Diablo Range is largely unpopulated outside of theSan Francisco Bay Area.Major nearby communities include,Antioch,Pittsburg,Concord,Walnut Creek,Alamo,Danville,San Ramon,Pleasanton,Livermore,Fremont,Milpitas,San Jose,Morgan Hill,andGilroyand the Central Valley city ofTracy.South of Pacheco Pass, the only major nearby communities (those with a population over 15,000) areLos Banos,andHollister.The small town ofCoalingamay also be notable for its location onState Route 198,one of the few routes through the mountains. Also the town ofKettleman Cityis also on State Route 41, another route that crosses the mountains. Towns west of the range south of Gilroy include:Salinas,King City,andPaso Robles.

The southern end ofHenry W. Coe State Park,nearGilroy

Protected areas

Most of the range consists of private ranchland, limiting recreational use. However, the range does contain several areas of parkland, includingMount Diablo State Park,Alum Rock Park,Grant Ranch Park,Henry W. Coe State Park,Laguna Mountain Recreation Area,and theBLM's Clear Creek Management Area. In addition, some private land is held inconservation easementsby theCalifornia Rangeland Trust.

Natural history

Since the range lies around 10–50 miles (16–80 kilometers) inland from the ocean, and other coastal ranges like theSanta Lucia Rangeand theSanta Cruz Mountainsblock 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 Mountainin 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 theNew Idriaquicksilver mines, which stopped production in the 1970s. Heavy mercury contamination has been documented in the San Carlos and Silver Creeks, which flow intoPanoche Creek,and thence into theSan 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 aSuperfundsite and scheduled for cleanup.

Flora

The Diablo Range is part of theCalifornia interior chaparral and woodlandsecoregion.It is covered mostly bychaparralandCalifornia oak woodlandcommunities, with stands ofclosed-cone pine forestsappearing above 4,000 feet (1,219 m). Thenative bunch grasssavannahas been predominantly replaced byannual Mediterranean grasses,except in some rarehabitatfragments. The understory is dominated with nonnative invasives. Blooming in spring are such plants asViola pedunculata,Dodecatheon pulchellum,Fritillaria liliacea,andRibes malvaceum,which can be viewed in theBlue Oak Ranch Reserve.

The range'sriparian zoneshave such trees asbigleaf maple(Acer macrophyllum),white alder(Alnus rhombifolia),California bay(Umbellularia californica), andCalifornia sycamore(Platanus racemosa).

The most common trees arecoast live oak(Quercus agrifolia) andblue oak(Quercus douglasii), with the largest blue oak growing in Alameda County. There are also good populations ofCalifornia buckeye(Aesculus californica), andCalifornia black oak(Quercus kelloggii). Thegray pine(Pinus sabiniana) and rarerCoulter 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 includeknobcone pine(Pinus attenuata),Jeffrey pine(Pinus jeffreyi) andponderosa pine(Pinus ponderosa).

Fauna

Threetule elkin Basking Ridge Park just north of U.S. Highway 101, which is a barrier to elk migration to theCoast Range

The Diablo Range attracts far moreraptorsthan coastal forests, such asred-tailed hawks.Golden eaglenesting sites are foundin the Diablo Range, reaching their highest density in southern Alameda County.

TheBay checkerspot butterfly,a federally listedthreatened species,has habitat in the Range, especially at Mount Diablo. TheCalifornia tiger salamander(Ambystoma californiense), also a federally threatened species and avulnerable speciesofamphibiannative toNorthern California,lives in ponds in the range.Thenorthern Pacific rattlesnakeis thriving, as are manyground squirrels,hares,and various species of native and nonnative rodents.

Tule elk(Cervus canadensis ssp. nannodes) were restored toMount Hamiltonbetween 1978-1981 and are slowly recovering in several small herds in Santa Clara and Alameda Counties. SeeMount Hamilton elk recovery.Black-tailed deerare abundant.Pronghorn,grizzly bears,andwolveswere extirpated in the 1800s. There still are numerouscoyotesand some of the more vitalmountain lionpopulations in the state. There are excellent populations ofbobcatsandgray 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.

See also

• Mountain ranges of the San Francisco Bay Area
• Rancho Cañada de Pala
• Rancho Santa Teresa