Geography of California

The geography of California is defined by its central feature--the Central Valley, a huge, fertile valley between the coastal mountain ranges and the Sierra Nevada to the east. In the North, the Central Valley is bounded by the Cascade Range, a rugged volcanic pinewood wilderness that extends into Oregon and the Klamath Mountains, a range of mountains in the northwest corner of the state. The northern part of the Central Valley is called the Sacramento Valley, after its river, and the southern part is called the San Joaquin Valley (pronounced "san wahkeen"), after its river. The whole Central Valley is watered by mountain-fed rivers (notably the San Joaquin, Kings, and Sacramento) that drain to the San Francisco Bay. The rivers are sufficiently large and deep that several inland cities, notably Stockton, California, are seaports.

In the northeast corner of the state lies the Modoc Plateau, a region of rolling hills of volcanic origin.

In the east of the state lies the Sierra Nevada, which runs north-south for 400 miles. The highest peak in the continental United States, Mount Whitney (4418 meters/14,495 feet) lies within the Sierra Nevada. The topography of the Sierra is shaped by uplift and glacial action.

The Sierra has 200-250 sunny days each year, warm summers, fierce winters, and varied terrain. The rare combination of rugged variety and pleasant weather leads many mountaineers to say that they are the most beautiful and accessible mountains in the world. The famous Yosemite valley lies in the Central Sierra. The large, deep freshwater Lake Tahoe lies to the North of Yosemite. The Sierra is also home to the giant sequoia, the most massive trees on Earth.

These features inspired the founding of the Sierra Club and the Alpine Club, public-service clubs of mountaineers devoted to maintaining trails and lodges and organizing outings to explore the Sierra. The most famous hiking and horse-packing trail in the Sierra is the John Muir Trail, which goes from the top of Mt. Whitney to Yosemite valley, and which is part of the Pacific Crest Trail that goes from Mexico to Canada.

To the east of the Sierra is the Basin and Range geological province, which extends into Nevada. The Basin and Range is a series of mountains and valleys (specifically horsts and grabens), caused by the extension of the Earth's crust. One notable feature of the Basin and Range is Mono Lake, which is the oldest lake in North America. The Basin and Range also contains the Owens Valley, the deepest valley in North America (more than 10,000 feet deep, as measured from the top of Mount Whitney).

To the west of the Central Valley lies the Coast Ranges, including the Diablo Range, just East of San Francisco, and the Santa Cruz Mountains, to the South of San Francisco. The Coast Ranges north of San Francisco become increasingly foggy and rainy. These mountains are noted for their coast redwoods, which live within the range of the coastal fog, the tallest trees on Earth.

Southern California is separated from the rest of the state by the east-west trending Transverse Ranges, including the Tehachapi, which separate the Central Valley from the Mojave Desert. Urban Southern California intersperses the valleys between the Santa Susana Mountains, Santa Monica Mountains and San Gabriel Mountains, which range from the Pacific Coast, eastward over 100 miles, to the San Bernardino Mountains, north of Palm Springs. The highest point of the range is Mt. San Gorgonio, whose eastern shoulder has a cable tram from the desert to a ski resort in the pine wilderness. It is possible to surf on the Pacific and ski on the same winter day in Southern California (but it takes planning to avoid the traffic congestion).

The southernmost mountains of California are the Peninsular Ranges, which are East of San Diego and continue into Mexico. The Peninsular Ranges contain the Santa Ana Mountains and the Palomar Mountain Range, notable for its famous Palomar observatory. Ninety miles northwest of Palomar, in the San Gabriel Mountains, is Mount Wilson observatory, where the redshift was discovered in the 1920s.

In the eastern part of the state, below the Sierra Nevada, there are a series dry lake beds that were filled with water during the last ice age (fed by ice melt from alpine glaciers but never directly affected by glaciation; see pluvial). Many of these lakes have extensive evaporate deposits that contain a variety of different salts. In fact, the salt sediments of many of these lake beds have been mined for many years for various salts, most notably borax (this is most famously true for Owens Lake and Death Valley).

There are harsh deserts in the Southeast of California. These deserts are caused by a combination of the cold offshore current, which limits evaporation, and the rain shadow of the mountains. The prevailing winds blow from the ocean inland. When the air passes over the mountains, adiabatic cooling causes most water in the air to rain on the mountains. When the air returns to sea level on the other side of the mountains, it recompresses, warms and dries, parching the deserts.

The Mojave Desert is bounded by the Tehachapi Mountains and the San Bernardinos. The boundaries are quite distinct, since they are outlined by the two largest faults in California: the San Andreas and the Gorlock. The Mojave Desert receives less than 6 inches of rain a year and is generally between 3000 and 6000 feet of elevation. The Mojave Desert also contains the lowest, hottest place on Earth: Death Valley, where temperature normally approaches 120 degrees Fahrenheit in late July and early August.

To the east of the Peninsular Ranges lies the Colorado Desert, which extends into Arizona and Mexico. One feature of the desert is the Salton Sea, an inland sea that was formed accidentally in 1901 by engineers cutting the western bank of the Colorado River.

The Pacific Ocean lies to the west of California. Sea temperatures rarely exceed 65 degrees Fahrenheit, even in summer, because of up-welling deep waters with dissolved nutrients. Therefore, most sea life in and around California more closely resembles Arctic, rather than tropical, biotopes. The sea off California is remarkably fertile, a murky green filled with fish, rather than the clear dead blue of most tropical seas. Before 1930, there was an extremely valuable sardine (herring) fishery off Monterey, but this was depleted, an event later famous as the background to John Steinbeck's Cannery Row.