| Peninsular Ranges | |
|---|---|
 Sierra San Pedro Mártir andDevils Peak, Southern Baja California, Mexico | |
| Highest point | |
| Peak | San Jacinto Peak |
| Elevation | 10,834 ft (3,302 m) |
| Geography | |
 | |
| Countries | |
| States | |
| Geology | |
| Rock age | Mesozoic |
| Rock type | Granite |
ThePeninsular Ranges (also called theLower California province) are a group of mountain ranges that stretch 930 mi (1,500 km) fromSouthern California to the southern tip of theBaja California peninsula; they are part of the North AmericanPacific Coast Ranges, which run along thePacific coast from Alaska to Mexico. Elevations range from 500 to 10,834 ft (150 to 3,300 m).[1]
The Peninsular Ranges include theSanta Ana Mountains, theTemescal Mountains, other mountains and ranges of thePerris Block, theSan Jacinto Mountains, theLaguna Mountains of southern California continuing from north to south with theSierra de Juárez, theSierra de San Pedro Mártir, theSierra de San Borja, theSierra de San Francisco, theSierra de la Giganta, and theSierra de la Laguna in Baja California.Palomar Mountain, home toPalomar Observatory, is in the Peninsular Ranges inSan Diego County, as are theSan Ysidro Mountains andViejas Mountain. The Peninsular Ranges run predominantly north-south, unlike theTransverse Ranges to their north, which mostly run east-west.
Rocks in the ranges are dominated byMesozoicgranitic rocks, derived from the same massive batholith which forms the core of theSierra Nevada Mountains in California. They are part of a geologic province known as theSalinian Block which broke off theNorth American plate as theSan Andreas Fault andGulf of California came into being.[2]
Between the Peninsular Ranges and theTransverse Ranges lies the complex Malibu Coast—Santa Monica—Hollywood fault, which exists as the border between these two mostly geologically unitary provinces.[3]
Most of the Peninsular Ranges are in theNearctic realm. Severalterrestrial ecoregions cover portions of the Peninsular Ranges. On the western side of the northern portion of the ranges, themontane sub-ecoregion of theCalifornia chaparral and woodlands ecoregion covers southern California and northern Baja California. On the western side of the southern portion of the ranges, theBaja California desert ecoregion covers the southern portion of the Peninsular Ranges in Baja California andBaja California Sur. On the eastern side of the northern ranges, theSonoran Desert ecoregion covers southeastern California and northeastern Baja California as far south as the town ofLoreto. On the eastern side of the Laguna Mountains inSan Diego County,Anza-Borrego Desert State Park is known for its springtime profusion ofColorado Desert (Sonoran) wildflowers. On the eastern (Gulf of California) side of the southern portion of the ranges, theGulf of California xeric scrub ecoregion covers the range in Baja California Sur.
The higher portions of the Peninsular Ranges, especially the west-facing slopes, are home toconiferous andmixed evergreen forests.Cleveland National Forest covers much of the higherSouthern California Peninsular Ranges. The vegetation includesoak woodlands and forests ofJeffrey pine (Pinus jeffreyi) andCoulter pine (Pinus coulteri). TheSierra Juarez and San Pedro Martir pine-oak forests cover the upper slopes of the Sierra Juarez and San Pedro Martir ranges in Baja California. These isolated forests are predominantly composed oftamarack pine (Pinus contorta subsp.murrayana),sugar pine (Pinus lambertiana),Parry pinyon(Pinus quadrifolia),white fir (Abies concolor),California incense cedar (Calocedrus decurrens), andjunipers. Oak species includecoast live oak (Quercus agrifolia),Engelmann oak (Quercus engelmannii),canyon live oak (Quercus chrysolepis), andBaja oak (Quercus peninsularis). These higher portions of the Peninsular Ranges harbor many rare andendemic species.
Southern Baja California Sur is part of theNeotropical realm. The southern end of the Baja California Peninsula, including theSierra de la Laguna Peninsular Range, was, like the rest of the peninsula, originally part of the Mexican mainland. It was sheared off the mainland, becoming at one time an island, and evolved in relative isolation from the northern part of the peninsula and ranges. Its flora and fauna share many affinities with southern Mexico andCentral America. It includes three distinct ecoregions, theSierra de la Laguna dry forests,Sierra de la Laguna pine-oak forests, andSan Lucan xeric scrub.
Media from Commons32°30′53″N115°40′30″W / 32.51480265°N 115.67512390°W /32.51480265; -115.67512390
