|Peak||San Jacinto Peak|
|Elevation||10,834 ft (3,302 m)|
|Countries||Mexico and United States|
|States||Baja California Sur, Baja California and California|
|Age of rock||Mesozoic|
|Type of rock||Granite|
The Peninsular Ranges (also called the Lower California province  ) are a group of mountain ranges that stretch 1,500 km (930 mi) from Southern California to the southern tip of the Baja California peninsula; they are part of the North American Coast Ranges, which run along the Pacific Coast from Alaska to Mexico. Elevations range from 150 to 3,300 m (500 to 10,834 ft).
The Peninsular Ranges include the Santa Ana Mountains, Temescal and other mountains and ranges of the Perris Block, 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, Sierra de la Giganta, and Sierra de la Laguna in Baja California. Palomar Mountain, home to Palomar Observatory, is in the Peninsular Ranges in San Diego County, 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.
Rocks in the ranges are dominated by Mesozoic 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 as the San Andreas Fault and Gulf of California came into being.[ citation needed ]
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. 
Most of the Peninsular Ranges are in the Nearctic realm. 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 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 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 San Diego County the Anza-Borrego Desert State Park is known for its springtime profusion of Colorado Desert (Sonoran) wildflowers. On eastern-Gulf of California 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 covers much of the higher Southern California 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 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 species.
Southern Baja California Sur is part of the Neotropical realm. 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. It includes three distinct ecoregions, the Sierra de la Laguna dry forests, Sierra de la Laguna pine-oak forests, and San Lucan xeric scrub.
The Baja California peninsula is a peninsula in northwestern Mexico. It separates the Gulf of California from the Pacific Ocean. The peninsula extends from Mexicali, Baja California, in the north to Cabo San Lucas, Baja California Sur, in the south.
Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of Baja California. It has an area of 70,113 km2 (27,071 sq mi) and comprises the northern half of the Baja California Peninsula, north of the 28th parallel, plus oceanic Guadalupe Island. The mainland portion of the state is bordered on the west by the Pacific Ocean; on the east by Sonora, the U.S. state of Arizona, and the Gulf of California; on the north by the U.S. state of California; and on the south by Baja California Sur.
The Pacific Coast Ranges are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Although they are commonly thought to be the westernmost mountain range of the continental United States and Canada, the geologically distinct Insular Mountains of Vancouver Island lie further west.
Sierra de San Pedro Mártir is a mountain range located within southern Ensenada Municipality and southern Baja California state, of northwestern Mexico.
The California chaparral and woodlands is a terrestrial ecoregion of southwestern Oregon, northern, central, and southern California and northwestern Baja California (Mexico), located on the west coast of North America. It is an ecoregion of the Mediterranean forests, woodlands, and scrub biome, and part of the Nearctic realm.
The Baja California Desert is a desert ecoregion of Mexico's Baja California Peninsula. This ecoregion occupies the western portion of the Baja California peninsula, and occupies most of the Mexican states of Baja California Sur and Baja California. It covers 77,700 square kilometers. The climate is dry, but its proximity of the Pacific Ocean provides humidity and moderates the temperature. The flora mostly consists of xeric shrubs and over 500 species of recorded vascular plants.
The Madrean pine–oak woodlands are subtropical woodlands found in the mountains of Mexico and the southwestern United States. They are a biogeographic region of the tropical and subtropical coniferous forests and temperate broadleaf and mixed forests biomes, located in North America.
The Sierra de Juárez, also known as the Sierra Juarez, is a mountain range located in Tecate Municipality and northern Ensenada Municipality, within the northern Baja California state of northwestern Mexico.
The Sierra Juárez and San Pedro Mártir pine–oak forests is a Nearctic temperate coniferous forests ecoregion that covers the higher elevations of the Sierra Juárez and Sierra San Pedro Mártir ranges of the Peninsular Ranges, of the northern Baja California Peninsula of Mexico. The pine–oak forests extend throughout the central portion of the Mexican state of Baja California and terminate near the border with the U.S. state of California.
The Sierra de la Laguna is a mountain range at the southern end of the Baja California Peninsula in Mexico, and is the southernmost range of the Peninsular Ranges System.
The Sierra de la Laguna pine–oak forests are a subtropical coniferous forest ecoregion, found in the Sierra de la Laguna mountain range at the southern tip of the Baja California Peninsula, Mexico.
The Sierra de la Laguna dry forests are a subtropical dry forest ecoregion of the southern Baja California Peninsula in Mexico.
The Sierra Madre Occidental pine–oak forests are a Temperate broadleaf and mixed forests ecoregion of the Sierra Madre Occidental range from the southwest USA region to the western part of Mexico. They are home to a large number of endemic plants and important habitat for wildlife.
California mixed evergreen forest is a plant community found in the mountain ranges of California and southwestern Oregon.
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 San Lucan xeric scrub is a xeric shrubland ecoregion of the southernmost Baja California Peninsula, in Los Cabos Municipality and eastern La Paz Municipality of southern Baja California Sur state, Mexico.
Constitution 1857 National Park is located in the pine forests of the Sierra de Juárez mountain range in the northern part of Baja California, Mexico. The park is an important preserve for many native wild animals like bighorn sheep and mule deer. The park is characterized by the large variety of coniferous plant species.
The California coastal sage and chaparral is a Mediterranean forests, woodlands, and scrub ecoregion located in southwestern California and northwestern Baja California (Mexico). It is part of the larger California chaparral and woodlands ecoregion.
The California montane chaparral and woodlands is an ecoregion defined by the World Wildlife Fund, spanning 7,900 square miles (20,000 km2) of mountains in the Transverse Ranges, Peninsular Ranges, and Coast Ranges of southern and central California. The ecoregion is part of the larger California chaparral and woodlands ecoregion, and belongs to the Mediterranean forests, woodlands, and scrub biome.
Southern California Coastal–Baja California is a freshwater ecoregion in Western North America. It covers portions of central and southern California and west of the Coast Ranges as well as most of Mexico's Baja California Peninsula, extending from the southern end of Monterey Bay to the southern tip of the Baja California Peninsula.
Coordinates: 29°57′N114°43′W / 29.95°N 114.72°W