SOUTHLAND CALIFORNIA SUMMARIZED HISTORY, FACTS,  AND DEMOGRAPHICS 

CALIFORNIA GEOGRAPHY 

Natural Regions 

California lies within four major natural regions, or physical geographic provinces. They are the Pacific Border province, the Sierra-Cascade province, the Basin and Range province, and the Lower Californian province.

The Pacific Border province, also called the Coastal Uplands, extends nearly the entire length of western California. It can be subdivided into four sections, the Klamath Mountains, the Coast Ranges, the Transverse Ranges, and the Great Central Valley.

The Klamath Mountains, partly in Oregon, occupy the northwestern corner of California. They include a number of separate ranges, such as the Salmon and Trinity mountains, and form a rugged forested area that rises to 2,700 m (9,000 ft).

The Coast Ranges parallel the Pacific Coast in a complex series of ridges and valleys. The only major low-lying pass through the ranges is formed by San Francisco Bay and its tributary bays, as they carry the waters of California's largest river, the Sacramento, into the Pacific Ocean at the Golden Gate. The principal range is the Diablo Range, which flanks the Central Valley and rises to 1,500 m (5,000 ft) above sea level. Between the interior Diablo Range and the coastal Santa Lucia Range lies the long Salinas valley.

The Transverse Ranges, so named because they run transverse or perpendicular (west to east) to the north-south oriented Coast Ranges, extend from Point Conception, on the coast, roughly eastward to the Mojave Desert. These generally narrow ranges increase in elevation toward the east, where Mount San Gorgonio in the San Bernardino Mountains rises to 3,505 m (11,499 ft) above sea level. The Transverse Ranges partly enclose low but often hilly Los Angeles and its suburbs.

The Great Central Valley is a vast structural depression that extends from northwest to southeast for 640 km (400 mi), with an average width of 80 km (50 mi). The valley is surrounded by mountain ranges that rise steeply from the valley floor on the west and more gently on the east. The Central Valley, with its flat land and rich alluvial soils, is one of the most productive agricultural regions in the world. The northern part of the valley is called the Sacramento Valley, and the southern part is called the San Joaquin Valley.

The Sierra-Cascade province is, in California, a vast upland area that extends from Oregon to the Transverse Ranges. It is subdivided into two sections, the southern Cascade Range and the Sierra Nevada.

      
The southern Cascade Range, in northern California, consists of a rugged belt of ranges that includes volcanic peaks and extensive lava flows. Mount Shasta, which is a dormant volcano, rises to 4,317 m (14,162 ft) above sea level. Just to the south of Lassen Volcanic National Park the densely forested Cascades meet the Sierra Nevada.

The Sierra Nevada, nearly all of which lies in California, is an imposing mountain barrier that extends along the eastern edge of the Central Valley. It is primarily a vast tilted granite block, with very steep slopes facing east and longer, gentler slopes facing west. The highest section, known as the High Sierra, includes Mount Whitney, which rises to 4,418 m (14,494 ft) and is the highest peak in the United States outside of Alaska. Forests cover large areas on the lower western slopes of the Sierra Nevada. At the southern end of the Sierra Nevada the Tehachapi Mountains curve southwestward to join the Coast Ranges and the Transverse Ranges.

The Basin and Range province is an arid area of mountain ranges, basins, and deserts. In California it is represented primarily by parts of the Great Basin and Sonoran Desert sections. Within the Great Basin lies Death Valley, whose lowest elevation, 86 m (282 ft) below sea level, is the lowest point in the Western Hemisphere. The Sonoran Desert section is characterized by numerous flat plains separated by low but rugged ranges. It includes the extensive Mojave, or Mohave, Desert. Also in this province is the Colorado Desert, roughly extensive with the Salton Trough. The trough is a depression that extends from the Gulf of California, in Mexico, to the Transverse Ranges in the northwest. This arid depression, rimmed by several mountain ranges, includes the Imperial Valley, the Salton Sea, and the Coachella Valley.

The Lower California province is a northern extension of Mexico's peninsula of Baja California. The province is dominated by occasional peaks but generally rolling mountain and valley terrain of the Peninsular Ranges. The northern end of the granitic Peninsular Ranges culminates in Mount San Jacinto (3,293 m/10,804 ft), which overlooks the resort city of Palm Springs to the east.