Peninsular Ranges

Geobox|Range
name=Peninsular Ranges


image_caption=
country=Mexico
country1=United States
state = Baja California Sur
state1 = Baja California
state2 = California
highest=Picacho del Diablo
highest_elevation_metric=3078m
geology=Granite
period=Mesozoic

The Peninsular Ranges (also called the Lower California province [cite book | last = Benke | first = Arthur C. | authorlink = | coauthors = Cushing, Colbert E. | title = Rivers of North America | publisher = Academic Press | date = 2005 | pages = 543 | isbn = 0120882531 ] ) are a group of mountain ranges which stretch 1500 km (900 miles) from southern California in the United States to the southern tip of Mexico's Baja California peninsula; they are part of the North American Coast Ranges that run along the Pacific coast from Alaska to Mexico. Elevations range from 500 ft to 11,500 ft (150 m to 3,500 m).

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.

The Peninsular Ranges include the Santa Ana Mountains, San Jacinto Mountains and Laguna Mountains of southern California with the Sierra Juarez, Sierra San Pedro Mártir, Sierra de la Giganta, and Sierra de la Laguna of Baja California. Mount Palomar, home to Palomar Observatory, is in the Peninsular Ranges in San Diego County. The Peninsular ranges run predominantly north-south, unlike the Transverse Ranges to their north, which mostly run east-west.

Ecology

Several terrestrial ecoregions cover portions of the Peninsular Ranges. Most of the ranges are in the Nearctic ecozone. On coast side of ranges, California chaparral and woodlands ecoregion covers the northern portion of the range, in southern California and northern Baja California. Baja California desert ecoregion runs along the coast side of the southern portion of the Peninsular Ranges. On eastern side of ranges, Sonoran Desert ecoregion covers southeastern California and northeastern Baja California as far south as the town of Loreto, Baja California Sur. Anza-Borrego Desert State Park, on the eastern side of the Peninsular Ranges in San Diego County, is famous for its springtime profusion of Sonoran Desert wildflowers. The Gulf of California xeric scrub ecoregion covering the southeastern portion of the peninsula and the islands of the Gulf of California.

The higher portions of the Peninsular Ranges, especially the west-facing slopes, are home to coniferous and mixed forests. Cleveland National Forest covers much of the southern California Peninsular Ranges, and includes oak woodlands and forests of Jeffrey Pine ("Pinus jeffreyi") and Coulter Pine ("P. coulteri"). Sierra Juarez and San Pedro Martir pine-oak forests cover upper slopes of Sierra Juarez and San Pedro Martir ranges. These isolated forests, predominantly pines, White Fir, junipers and oaks, harbor many rare and endemic species.

The southern end of the Baja California Peninsula, including the Sierra de la Laguna, was formerly an island, and evolved in relative isolation from the northern part of the peninsula. It is considered part of the Neotropic ecozone, and 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.

References