California Geography: The Land

Geography and Landforms of California

California has a diverse landscape made up of many unique geographic areas including the rocky Coastal Ranges, the Central Valley, the Klamath Mountains, the Transverse Range, the Cascades, the Sierra Nevada, and the Great Basin.

The state's coastal area consists of a series of low mountains that extend for 1200 miles along the Pacific Ocean. Beautiful valleys separate the individual ranges. They include the Napa Valley to the north and the Salinas Valley to the south. This region is also home to California's famous redwood trees. The San Andreas Fault is an important feature of this coastal area. The fault enters northern California from the Pacific Ocean and extends into southern California. Movements of the earth's crust along this fault line have caused many earthquakes.

California is made up of these Physiographic Areas

Basin and Range

The Basin and Range is a large physiographic area covering most of Nevada, part of eastern California, western Utah, and southeast Idaho. It lies in the rainshadow of the Sierra Nevada, south of the Columbia Plateau and north of the Mohave Desert, and is a mosaic of xeric basins, scattered mountains, and salt flats. It is hotter and contains more and higher mountains than the Columbia Plateau, with more perennial streams and ponderosa pine forest at the higher elevations. Compared to the Mojave Desert, it is not as hot and is more dominated by shrubland and less by grassland.

Central and Southern California Coast and Valleys

This physiographic area covers the central and southern coast of California, including the San Francisco Bay and extending to the Mexican border. In the interior it includes the Central Valley and foothills of the Sierra Nevada. Chaparral is the climax vegetation of areas characterized by a Mediterranean climate. Various oaks and other evergreen trees dominate many of the foothills. The Central Valley was a wetland-grassland complex dissected by riparian strips. This is a diverse area with a high degree of endemism.

Columbia Plateau

This is an arid sagebrush steppe and grassland surrounded on the north, west, and east by moister, predominantly forested, mountainous ecological regions. It is an oddly shaped physiographic area that covers portions of Washington, Oregon, Idaho, Nevada, and a small piece of northeast California. It consists of arid tablelands, intermontane basins, dissected lava plains, and widely scattered low mountains. There is a more subtle transition to the Basin and Range to the south in which hotter lowlands are dissected by isolated mountain ranges.

Mojave Desert

In the "Great American Desert" of the Southwest, the Mohave lies between and is intermediate in nature between the Great Basin to the north and the Sonoran Desert to the south and east. It is mostly in southeast California but extends also into southern Nevada, northwest Arizona, a very small part of southwest Utah, and lies in the rainshadow of the Southern California Ranges to the west. Its most prominent features are broad, sparsely vegetated plains. However, it also includes dry lakes, sharply rising buttes and relatively small mountain ranges, and its eastern portion is cut through by the Colorado River. It is generally a higher elevation desert than the Sonoran, although elevation descends to -300 m in Death Valley. Low precipitation, most falling in winter, with low winter and high summer temperatures are characteristic.

Sierra Nevada

The Sierra Nevada range, mostly within California and barely extending into Nevada, rises sharply from the arid basin and range on the east and slopes gently toward the Central Valley of California on the west. Vegetation at lower elevations is dominated by lodgepole pine on the east and ponderosa pine on the west, with fir, spruce, and alpine tundra at higher elevations.

Southern Sierra started to form in the Triassic period when an island arc collided with the West coast of North America and raised a set of mountains. At roughly the same time, the oceanic plate started to dive beneath the North American plate. Magma from the melting oceanic plate rose in plumes (plutons) from 115 million to 87 million years ago deep underground, their combined mass forming what is called the Sierra Nevada batholith. By 65 million years ago, the proto-Sierra Nevada was worn down to a range of rolling low mountains, a few thousand feet high.

Twenty million years ago, crustal extension associated with the Basin and Range Province caused extensive volcanism in the Sierra. About 4 million years ago, the Sierra Nevada started to form and tilt to the west. Rivers started cutting deep canyons on both sides of the range. The Earth's climate cooled, and ice ages started about 2.5 million years ago. Glaciers carved out characteristic U-shaped canyons throughout the Sierra. The combination of river and glacier erosion exposed the uppermost portions of the plutons emplaced millions of years before, leaving only a remnant of metamorphic rock on top of some Sierra peaks.

Sonoran Desert

The Sonoran Desert receives a low and unevenly distributed amount of precipitation over extensive plains and isolated mountains surrounding the northern end of the Gulf of California. In the United States it is centered in southwest Arizona and southeast California and extends south through most of Baja California Norte and Sur and the western half of the state of Sonora. Vegetation is sparse and differs from other American deserts by a greater dominance of trees, including arborescent cacti such as the saguaro. Creosote is a common and widely distributed shrub.

Southern Pacific Rainforests

This moist physiographic area extends from the Pacific coastline of Washington and Oregon inland to the crest of the Cascade Mountains. It ends arbitrarily at the Canadian border, and also includes the coastal ranges of northwestern California. Save for coastal estuaries and some inland drier valleys (the Willamette and the Puget Trough), the natural vegetation is coniferous forest. There are six coniferous forest types, defined by elevation and latitude, including the coastal Sitka spruce zone, low-elevation western hemlock/western red cedar, mid-elevation Pacific silver fir zone, subalpine mountain hemlock, a mixed-conifer zone in the Klamath/Siskiyou Mountains, and the redwood forest of northwest California.

California Landscape and Landforms:

Coastal Ranges

These Ranges in the north reach inland 20 to 30 miles extend from the Klamath Mountains in the north south to Santa Barbara. The Diablo and Santa Cruz Mountains are located in the Coastal Ranges. Napa Valley separates these ranges. The legendary Redwoods and the San Andreas Fault are located in the Coastal Ranges. The San Andreas Fault enters California from the Pacific Ocean near Port Arena and extends southeast into the state. Earthquakes are caused by movement of the earth's crust along this fault

Central Valley

This is a fertile area that extends 500 miles from the northwest to the southeast. Farmland is located in this region. The San Joaquin and the Sacramento, two of the state's largest river systems are located in the Central Valley. To the east of the Central Valley is the Sierra Nevada region, a 400-mile long area of massive granite rock. The highest point in the continental United States, Mt. Whitney, with an elevation of 14,495 feet, is located here. Mt. Shasta and Mt. Lassen, two volcanic peaks, lie to the north of the Sierra Nevada. They are part of the Cascade Mountains.

Klamath Mountains

The Klamath Mountains are located in the northwestern portion of the state. They consist of several small, forested ridges that are higher and steeper than the coastal ranges farther south. These ridges are separated by deep canyons and valleys.

The Sierra Nevada

The Sierra Nevada range, mostly within California and barely extending into Nevada, rises sharply from the arid basin and range on the east and slopes gently toward the Central Valley of California on the west.

The Sierra Nevada mountain range runs about 430 miles from north to south and forming a giant wall rising to over 14,000 feet.

Cascade Mountains:

The Cascade Mountains extend north from the Sierra Nevada mountain range. They were formed by volcanoes unlike the other mountain ranges in California and support one still-active volcano; Lassen Peak.

Transverse Range (The Los Angeles Ranges)

The Transverse Range runs east to west, creating a geographic boundary between northern and southern California. The Peninsular Ranges located to the south cover the southwestern tip of the state.

Great Basin

The Great Basin Region is part of a larger area that extends into Nevada and Oregon. In northern California, it is a lava plateau. To the south, it is an area of wastelands that include the Mojave Desert and the Colorado Desert. North America's lowest point, Death Valley, 282 feet below sea level, is located in the Great Basin.