The Peninsular Ranges (also called the Lower California province) are a group of mountain ranges that stretch from

Southern California Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban ...

to the southern tip of the Baja California peninsula; they are part of the North American

Coast Ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Although ...

, which run along the Pacific Coast from Alaska to Mexico.

Elevation The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § ...

s range from .

Geography

The Peninsular Ranges include the

Santa Ana Mountains The Santa Ana Mountains are a short peninsular mountain range along the coast of Southern California in the United States. They extend for approximately southeast of the Los Angeles Basin largely along the border between Orange and Riverside ...

, Temescal and other mountains and ranges of the

Perris Block The Perris Block is the central block of three major fault-bounded blocks of the northern part of the Peninsular Ranges. The Perris Block lies between the Santa Ana Block to the west and the San Jacinto Block to the east. The Perris Block, was ...

, San Jacinto and Laguna ranges of southern California continuing from north to south with the Sierra de Juárez, Sierra de San Pedro Mártir, Sierra de San Borja,

Sierra de San Francisco The Sierra de San Francisco is a mountain range in Mulegé Municipality of the northern region of Baja California Sur state, in northwestern Mexico. Geography The Sierra de San Francisco are on the eastern side of the Baja California Peninsula, ...

, Sierra de la Giganta, and Sierra de la Laguna in Baja California.

Palomar Mountain Palomar Mountain ( ; es, Monte Palomar ) is a mountain ridge in the Peninsular Ranges in northern San Diego County. It is famous as the location of the Palomar Observatory and Hale Telescope, and known for the Palomar Mountain State Park. His ...

, home to Palomar Observatory, is in the Peninsular Ranges in

San Diego County San Diego County (), officially the County of San Diego, is a county in the southwestern corner of the U.S. state of California. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county and the f ...

, as are Viejas Mountain and the San Ysidro Mountains. The Peninsular ranges run predominantly north-south, unlike the Transverse Ranges to their north, which mostly run east-west.

Geology

Rocks in the ranges are dominated by

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

granitic rocks, derived from the same massive batholith which forms the core of the Sierra Nevada Mountains in California. They are part of a geologic province known as the Salinian Block which broke off the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Paci ...

as the

San Andreas Fault The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizontal) ...

and

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...

came into being. Between this set of ranges and the Transverse Ranges is the complex Malibu Coast—Santa Monica— Hollywood fault, which exists as the border between these two mostly geologically unitary provinces.

Ecology and flora

Nearctic

Most of the Peninsular Ranges are in the

Nearctic realm The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America t ...

. Several terrestrial ecoregions cover portions of the Peninsular Ranges. On western-coast side of the northern portion of the ranges the California montane chaparral and woodlands sub-ecoregion of the

California chaparral and woodlands The California chaparral and woodlands is a terrestrial ecoregion of southwestern Oregon, northern, central, and southern California (United States) and northwestern Baja California (Mexico), located on the west coast of North America. It is a ...

ecoregion covers in southern California and northern Baja California. On western-coast side of the southern portion of the ranges the Baja California Desert ecoregion covers in the southern portion of the Peninsular Ranges in Baja California and Baja California Sur. On eastern side of northern ranges, the

Sonoran Desert The Sonoran Desert ( es, Desierto de Sonora) is a desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States (in Ariz ...

ecoregion covers southeastern California and northeastern Baja California as far south as the town of Loreto, Baja California Sur. On the eastern side of the Laguna Mountains in

the Anza-Borrego Desert State Park is known for its springtime profusion of Colorado Desert (Sonoran) wildflowers. On eastern-

side of the southern portion of the ranges the Gulf 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 to coniferous and mixed evergreen forests.

Cleveland National Forest Cleveland National Forest encompasses 460,000 acres (), mostly of chaparral, with a few riparian areas. A warm dry mediterranean climate prevails over the forest. It is the southernmost U.S. National Forest of California. It is administered by ...

covers much of the higher

Peninsular Ranges. The vegetation includes oak woodlands and forests of Jeffrey Pine (''Pinus jeffreyi'') and Coulter Pine (''Pinus coulteri''). The

Sierra Juarez and San Pedro Martir pine-oak forests Sierra (Spanish for "mountain range" and "saw", from Latin '' serra'') may refer to the following: Places Mountains and mountain ranges * Sierra de Juárez, a mountain range in Baja California, Mexico * Sierra de las Nieves, a mountain range ...

cover upper slopes of Sierra Juarez and San Pedro Martir ranges in Baja California. These isolated forests, predominantly Tamarack Pine (''Pinus contorta'' subsp. ''murrayana''), Sugar Pine (''Pinus lambertiana''), Parry Pinyon ''(Pinus quadrifolia)'', White Fir (''Abies concolor''), California Incense Cedar (''Calocedrus decurrens''), and junipers. Oak species include Coast Live Oak (''Quercus agrifolia''), Engelmann Oak (''Quercus engelmannii''), Canyon Live Oak (''Quercus chrysolepis''), and Baja Oak (''Quercus peninsularis''). These higher portions of the Peninsular Ranges harbor many rare and

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

species.

Neotropic

Southern Baja California Sur is part of the

Neotropical realm The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In bioge ...

. The southern end of the Baja California Peninsula, including the Sierra 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 and

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

. It includes three distinct ecoregions, the Sierra de la Laguna dry forests, Sierra de la Laguna pine-oak forests, and San Lucan xeric scrub.

References

External links

{{California Faults Lists of mountain ranges Geologic provinces of California Mountain ranges of Baja California Mountain ranges of Baja California Sur Mountain ranges of Mexico Mountain ranges of San Diego County, California Mountain ranges of Southern California Pacific Coast Ranges Physiographic sections Physiographic regions of Mexico Physiographic regions of the United States