California Physical Geography

California Physical Geography


As a result of North America’s westward movement, ocean crust beneath the rim of North America has moved into the mantle over millions of years, sometimes pressing pieces of the Earth’s crust against the continent and merging with it. The geology of the western fringe of North America consists of terrains thus merged, which have been pushed together to form the mountain ranges and basins of the North American Cordillera. When pieces of the Earth’s crust were moved into the mantle, large amounts of magma were formed, which rose to the surface and in front of it.caused volcanism. Today, active volcanoes are only found in the Cascades, but virtually all of California’s mountain ranges have been volcanically active in the past.

According to, about 25 million years ago, the movement of the tectonic plates changed from a facing to a sliding situation. This movement created a system of side shear faults, the largest of which is the San Andreas fault. The area west of this fault (the coastal strip, which includes the cities of San Diego, Los Angeles and San Francisco) is moving north relative to the rest of North America at an average rate of about 5 cm per year. Movement along the faults is not gradual, but incremental, with the tension building up to be released all at once in the form of an earthquake. The state has experienced several major earthquakes in the past. The most famous is probably the earthquake of 1906, which flattened much of San Francisco. More recently, extensive damage was caused by the 1989 Loma Prieta earthquake in the Bay Area, which collapsed part of the Bay Bridge, and the 1994 Northridge earthquake near Los Angeles.

Summer often brings fog to the coastal strip and the Central Valley, like here around the Golden Gate Bridge


California has large differences in climate, mainly due to the enormous surface area, the topography and the proximity to the ocean. Ocean temperature is determined by the California Current, a cold current along the US west coast. In summer it often causes fog along the coast. The ocean also ensures mild, wet winters and gives the coastal strip in the north a maritime climate (Cfb in the Köppen climate classification) and in the center and south (approximately from Cape Mendocino) a Mediterranean climate (Csb according to Köppen). The ocean is also responsible for precipitation, which is mainly accommodated by the western slopes of the Pacific Coast Ranges and the Sierra Nevada. Some places in the Coast Ranges receive more than 2,500 mm of precipitation per year. The climate is becoming drier in the interior and in the south. Temperature differences also increase from the coast: the climate is more continental in the interior .

Steppe met typische “Joshua trees” (Yucca brevifolia), Joshua Tree National Park

The Central Valley has a warm Mediterranean climate (Csa according to Köppen), with subtropical warm dry summers and mild wet winters. Much of the south and center of the state has a steppe climate in the interior (BSk according to Köppen), with noticeably colder winters and hotter summers. The coastal strip around San Diego in the extreme southwest has a warm steppe climate (Köppen: BSh), while many inland areas in the south of the state have a desert climate (Köppen: BWh). Death Valley has the highest temperatures ever recorded in the Western Hemisphere. On July 10, 1913, the mercury rose to 57 °C. In July, the average daily temperature in Death Valley is 38°C.

The high mountains, such as the Sierra Nevada, the Cascades and the Klamath Mountains, have a high mountain climate (Köppen: EH) with a lot of snowfall in winter and moderately warm summers. The area in the rain shadow east of the Sierra Nevada has a dry desert climate.

Unlike the southeastern United States, California is almost never hit by hurricanes, despite its proximity to the ocean. This is due to the cold California Current and to the fact that hurricanes usually move westward in the Northern Hemisphere.

Flora and fauna

Due to the large differences in climate and topography, California has a very diverse ecology. The state is located in the Nearctic region and includes a number of widely different ecoregions and biomes. California has a large number of endemic species, species not found anywhere else, both plants and animals. These include both relict species and species that have arisen through adaptation to local conditions, such as the Ceanothus plant . The flora of the areas west of the rain shadow can be seen as a flora kingdom of their own, de California Floristic Province.

The areas to the east, in the rain shadow of the high mountain ranges, consist of desert and xerophytic scrub. The lowland areas of southeastern California are part of the Sonoran Desert ecoregion, which also covers parts of Arizona. Further north, the Mojave Desert forms an ecoregion that sits between the Sonoran Desert and the scrub steppe of the Great Basin.

Forest on the western slopes of the Sierra Nevada mainly consists of giant sequoias (Sequoiadendron giganteum) and Douglas fir (Pseudotsuga menziesii)

The southern and central coastal areas have a vegetation of savanna, oak forest, coniferous forest, chaparral, sage forest and scrub and grassland, depending on the wind, amount of light, precipitation and soil type. This vegetation continues south into northwestern Baja California and forms a ring around the Central Valley, forming the lower ecozone of the western slopes of the Sierra Nevada. The Central Valley itself would be covered with grassland in natural conditions. Today, however, the native perennial grasses have been displaced in most places by imported annual exotics, which benefited agriculture. Originally, the grasslands of the Central Valley were grazed by wapiti (Cervus canadensis) and pronghorn (Antilocapra americana). The pronghorn is nowadays only found on the Modoc Plateau, while the wapiti has almost completely disappeared.

Many migratory birds use California as a place to hibernate or migrate through the state each year on their way to wintering grounds further south. Large numbers of ducks and geese overwinter in the Central Valley. Herons and cormorants are migratory along the coast.

A colony of elephant seals off the coast

The higher western slopes of the Sierra Nevada and the mountains of northern California are covered with coniferous forest. Giant sequoias (Sequoia giganteum) grow in the Sierra Nevada, the thickest trees in the world. In addition, the Coast Ranges of northern California grow the tallest trees in the world, these are coast redwoods (Sequoia sempervirens). The coniferous forest of the Klamath Mountains has a particularly great diversity of conifer species. The grizzly bear (Ursus arctos horribilis), the symbol of California, has been wiped out statewide, but the smaller black bear (Ursus americanus)still occurs in the Sierra Nevada and the northern mountain areas. Like the coyote (Canis latrans), red lynx (Lynx rufus), and fox (Vulpes vulpes), introduced by European settlers in the 18th century, black bears are sometimes found near human settlements, where they have learned to look for food in the garbage. Other notable mammal species include the silver badger (Taxidea taxus), the Canadian beaver (Castor canadensis), the gray squirrel (Sciurus carolinensis)and several marten species (including the rare fish marten (Martes pennanti)).

The ocean and beaches are inhabited by several species of seals, elephant seals (Mirounga angustirostris) and sea lions. The annual migration route of the gray whale (Eschrichtius robustus) runs along the coast. California birds of prey include the golden eagle (Aquila chrysaetos) and the endangered California condor (Gymnogyps californianus).

There are 48 species of snakes in California, seven of which belong to the rattlesnake. There are 12 species of turtles, five of which are sea turtles and only come ashore to lay their eggs. Of the 47 lizard species, the East African three-horned chameleon (Trioceros jacksonii) is a well-known species. The subspecies Trioceros jacksonii xantholophushas been expelled by man. The amphibians are represented by 30 species of frogs. Two other frog species native to California are believed to be extinct. Finally, there are 43 species of salamanders in California, belonging to five different families. The California tiger salamander (Ambystoma californiense) is endemic to this state and is found nowhere else in the world.

California Physical Geography