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Central Valley
Great Central Valley, The Valley
Topography, major parts and cities of the Central Valley
Location	California, United States
Long-axis length	450 mi (720 km)
Width	40 to 60 miles (64 to 97 km)
Area	22,500 square miles (58,000 km2)
Depth	2,000 to 6,000 feet (610 to 1,800 m)
Geology
Type	Alluvial
Age	2-3 million years
Geography
Bounded by	Sierra Nevada (east), Cascade Range, Klamath Mountains (north), Coast Range, San Francisco Bay (west), Tehachapi Mountains (south)
Population centers	Redding, Chico, Yuba City, Sacramento, Stockton, Porterville, Modesto, Merced, Fresno, Visalia, Bakersfield, Clovis
Traversed by	Interstate 5, Interstate 80, State Route 99

Part of the Valley as seen from the air

Counties of the Central Valley

California's Central Valley is a large, flat valley that dominates the central portion of California. It is home to California's most productive agricultural areas. The valley stretches approximately 450 miles (720 km) from northwest to southeast inland and parallel to the Pacific Ocean coast. Its northern half is referred to as the Sacramento Valley, and its southern half as the San Joaquin Valley. The Sacramento valley receives about 20 inches of rain annually, but the San Joaquin is very dry, often semi-arid desert in many places.

The two halves meet at the huge Sacramento-San Joaquin River Delta of the Sacramento and San Joaquin Rivers, which along with their tributaries drain the majority of the valley. The Delta is a large expanse of interconnected canals, streambeds, sloughs, marshes and peat islands. The Central Valley covers an area of approximately 22,500 square miles (58,000 km²), making it slightly smaller than the state of West Virginia and about 13.7% of California's total area.

Boundaries and population[link]

The Central Valley is 40 to 60 miles (60 to 100 km) wide, the Sierra Nevada to the east and the Coast Ranges and San Francisco Bay to the west, as far south as the Tehachapi Mountains. The valley is a vast agricultural region drained by the Sacramento and San Joaquin rivers. Counties commonly associated with the valley:^[1]

• North Sacramento Valley (Shasta, Tehama, Glenn, Butte, Colusa)
• Sacramento Metro (Sacramento, El Dorado, Sutter, Yuba, Yolo, Placer)
• North San Joaquin (San Joaquin, Stanislaus, Merced)
• South San Joaquin (Madera, Fresno, Kings, Tulare, Kern)

About 6.5 million people live in the Central Valley today, and it is the fastest growing region in California.^{[citation needed]} There are 10 Metropolitan Statistical Areas (MSA) in the Central Valley. Below, they are listed by (MSA) population. The largest city is Fresno, followed by the state capital Sacramento.

Geology[link]

The flatness of the valley floor contrasts with the rugged hills or gentle mountains that are typical of most of California's terrain. The valley is thought to have originated below sea level as an offshore area depressed by subduction of the Farallon Plate into a trench further offshore. The San Joaquin Fault is a notable seismic feature of the Central Valley.

An example of the extreme differences between the geology of the valley floor and that of the rugged hills of the Coast Ranges (Between Tracy and Patterson, CA:Interstate 5)

The valley was later enclosed by the uplift of the Coast Ranges, with its original outlet into Monterey Bay. Faulting moved the Coast Ranges, and a new outlet developed near what is now San Francisco Bay. Over the millennia, the valley was filled by the sediments of these same ranges, as well as the rising Sierra Nevada to the east; that filling eventually created an extraordinary flatness just barely above sea level; before California's massive flood control and aqueduct system was built, the annual snow melt turned much of the valley into an inland sea.

The one notable exception to the flat valley floor is Sutter Buttes, the remnants of an extinct volcano just to the northwest of Yuba City which is 44 miles (71 km) north of Sacramento.

Another significant geologic feature of the Central Valley lies hidden beneath the delta. The Stockton Arch is an upwarping of the crust beneath the valley sediments which extends southwest to northeast across the valley.

Physiographically, the Central Valley lies within the California Trough physiographic section, which is part of the larger Pacific Border province, which in turn is part of the Pacific Mountain System.^[2][3]

Environment[link]

Map of the Central Valley grasslands ecoregion.

The 'Central Valley Grassland' is the Nearctic temperate and subtropical grasslands, savannas, and shrublands ecoregion which was once a diverse grassland containing areas of desert grassland (at the southern end), prairie, savanna, riverside woodland, marsh, several types of seasonal vernal pool, large lakes such as now-dry Tulare Lake, the largest lake in the United States west of the Mississippi, Buena Vista Lake and Kern Lake. However much of the Central Valley environment has been removed or altered by human activity including the introduction of exotic plants, especially grasses. The oak woodlands and chapparal that fringe the valley have been categorised as the California interior chaparral and woodlands ecoregion.^[4] The wetlands have been the target of rescue operations to restore areas nearly destroyed by agriculture.^[5]

Flora[link]

The dominant grass of the valley was Nassella pulchra mixed with other species, but today only 1% of the grassland in the valley is original and intact. Grassland flowers include California poppy (Eschscholzia californica), lupins, and Purple Owl's Clover (Castilleja exserta) which can still be seen, especially in Antelope Valley in the Tehachapi hills. Riverside trees include willows, western sycamore (Platanus racemosa), box elder (Acer negundo), Fremont cottonwood (Populus fremontii), and the endemic Valley oak (Quercus lobata).

Fauna[link]

The Central Valley was once home to large populations of pronghorn antelope (Antilocapra americana), elk including the endemic Tule Elk subspecies (Cervus elaphus nannodes), mule deer (Odocoileus hemionus), California ground squirrels, gophers, mice, hare, rabbits and kangaroo rats, along with their predators including the San Joaquin Kit Fox which is now an endangered subspecies surviving on the hillsides of the San Joaquin Valley. The wetlands of the Valley were an important habitat for wintering waterbirds and migrating birds of other kinds. Reptiles and amphibians of the valley include the endemic San Joaquin coachwhip snake (Masticophis flagellum ruddocki), blunt-nosed leopard lizard (Gambelia sila), Gilbert's skink (Eumeces gilberti) and the western aquatic garter snake (Thamnophis couchii). There are also a number of endemic invertebrates.

Threats and preservation[link]

Agriculture, especially the creation of grazing land, and the draining of lakes and rivers have radically altered the habitats of the Valley. Most of the grassland has been overtaken by new species, most of the vernal pools have been drained or otherwise destroyed with only those on the higher slopes remaining, the marshland has mostly been drained too, and the riverbank woodlands have nearly all been affected.

The Great Valley Grasslands State Park preserves an example of the native grass habitat in the valley, while oak savanna habitats remain near Visalia. There are areas of wetland and riverside woodland in the north especially on the Sacramento River system including the Nature Conservancy’s Cosumnes River Preserve just south of Sacramento, Gray Lodge Wildlife Area, Butte Sink Wildlife Management Area, and other patches in the delta area. Remaining vernal pools include Pixley National Wildlife Refuge between Tulare, California and Bakersfield and Jepson Prairie Preserve in the delta. There are large blocks of desert scrubland in the southern San Joaquin Valley and in the Carrizo Plain which is just outside the valley but has a similar landscape.

All these patches of natural habitat are disconnected and this is particularly damaging for wildlife that is used to migrating along the rivers of the valley, birds such as warblers and cuckoos, and reptiles and amphibians. Meanwhile clearance and alteration are ongoing.

Climate[link]

Tule fog in Stanislaus County in December

The northern Central Valley has a hot Mediterranean climate (Koppen climate classification Csa); the more southerly parts in rainshadow zones are dry enough to be Mediterranean steppe (BShs, as around Fresno) or even low-latitude desert (BWh, as in areas around Bakersfield). It is hot and dry during the summer and cool and damp in winter, when frequent ground fog known regionally as "tule fog" can obscure vision. Summer daytime temperatures approach 100 °F (38 °C), and common heat waves might bring temperatures exceeding 115 °F (46 °C). Mid Autumn to mid spring comprises the rainy season — although during the late summer, southeasterly winds aloft can bring thunderstorms of tropical origin, mainly in the southern half of the San Joaquin Valley but occasionally to the Sacramento Valley. The northern half of the Central Valley receives greater precipitation than the semidesert southern half. Frost occurs at times in the winter months, but snow is extremely rare.^[6]

Tule fog[link]

Tule fog ( /ˈtuːliː/) is a thick ground fog that settles along the length of the Great Central Valley. Tule fog forms during the late fall and winter (California's rainy season) after the first significant rainfall. The official time frame for tule fog to form is from November 1 to March 31. This phenomenon is named after the tule grass wetlands (tulares) of the Central Valley. Accidents caused by the tule fog are the leading cause of weather-related casualties in California.

Hydrography[link]

Sacramento River watershed

San Joaquin River watershed and Tulare Basin

Two major river systems drain and define the two parts of the Central Valley. The Sacramento River, along with its tributaries the Feather River and American River, flows southwards through the Sacramento Valley for about 447 miles (719 km).^[7] In the San Joaquin Valley, the San Joaquin River flows roughly northwest for 365 miles (587 km), picking up tributaries such as the Merced River, Tuolumne River, Stanislaus River and Mokelumne River.^[8]

In the south part of the San Joaquin Valley, the alluvial fan of the Kings River and another one from Coast Ranges streams have created a divide and resultantly the currently dry Tulare basin of the Central Valley, into which flow four Sierra Nevada rivers including the Kings. This basin, usually endorheic, formerly filled during heavy snowmelt and spilled out into the San Joaquin River. Called Tulare Lake, it is usually dry nowadays because the rivers feeding it have been diverted for agricultural purposes.^[9]

The rivers of the Central Valley converge in the Sacramento-San Joaquin Delta, a complex network of marshy channels, distributaries and sloughs that wind around islands mainly used for agriculture. Here the freshwater of the rivers merges with tidewater, and eventually reach the Pacific Ocean after passing through Suisun Bay, San Pablo Bay, upper San Francisco Bay and finally the Golden Gate. Many of the islands now lie below sea level because of intensive agriculture, and have a high risk of flooding, which would cause salt water to rush back into the delta, especially when there is too little fresh water flowing in from the Valley.^[10]

The Sacramento River carries the vast majority of the runoff, about 24,000 cubic feet per second (680 m³/s), while the San Joaquin averages a comparatively mere 4,500 cubic feet per second (130 m³/s). Over 25 million people, living both in the valley and in other regions of the state, rely on the water carried by these rivers.^[11]

Engineering[link]

Runoff from the Sierra Nevada and the resulting rivers that flow into San Francisco Bay provide some of the largest water resources of California. The Sacramento River is the second largest river to empty into the Pacific from the Continental United States, behind only the Columbia River and greater than the Colorado River.^[12] Combined with the fertile and expansive area of the Central Valley’s floor, the Central Valley is ideal for agriculture.^[13]

Today, the Central Valley is one of the most productive farming regions of the United States, but water control was desperately needed to prevent rivers from overflowing during the spring and summer while drying to a trickle in the autumn and winter.^[14] As a result, many large dams, including Shasta Dam, Oroville Dam, Folsom Dam, New Melones Dam, Don Pedro Dam, Friant Dam, Pine Flat Dam and Isabella Dam, were constructed on rivers entering the Central Valley, many part of the Central Valley Project.^[14] These dams have had a profound impact on the physical and ecological state of Central Valley rivers, including the loss of the chinook salmon.^[15]

Rapid development and growth of California’s two major urban areas, the San Francisco Bay Area and the Los Angeles/Inland Empire/San Diego metropolitan areas, meant that an enormous new demand was placed on local water resources that were not enough to support the population alone. The Central Valley was looked to as a water source, leading to the creation of the California State Water Project, which was contrived to transport water to parched, thirsty Southern California.^[16]

Runoff from the Sacramento and San Joaquin Rivers is intercepted in the delta by a series of massive pumps and canals, which divert water into the California Aqueduct that runs south along the entire length of the San Joaquin Valley.^[17] The flow of the Sacramento River is further supplemented by a tunnel from the Trinity River (a tributary of the Klamath River, northwest of the Sacramento Valley) near Redding.^[18] Cities of the San Francisco Bay Area, also needing great amounts of water, built aqueducts from the Mokelumne River and Tuolumne River that run east to west across the middle part of the Central Valley.^[19][20]

Flooding[link]

Most lowlands of the Central Valley are prone to flooding, especially in the old Tulare Lake, Buena Vista Lake, and Kern Lake beds. The Kings, Kaweah, Tule and Kern rivers originally flowed into these seasonal lakes, which would expand each spring to flood large parts of the southern San Joaquin Valley. Due to the construction of farms, towns and infrastructure in these lakebeds while preventing them from flooding with levee systems, the risk of floods damaging properties increased greatly.

Major public works projects beginning in the 1930s sought to reduce the amount of snowmelt flooding by the building of large dams. In 2003, it was determined that Sacramento had both the least protection against and nearly the highest risk of flooding. Congress then granted a $220 million loan for upgrades in Sacramento County.^[21] Other counties in the valley that face flooding often are Yuba, Stanislaus, and San Joaquin.

Economy[link]

Agriculture is the primary industry in most of the Central Valley. A notable exception to the predominance of agriculture has been the Sacramento area, where the large and stable workforce of government employees helped steer the economy away from agriculture. Despite state hiring cutbacks and the closure of several military bases, Sacramento's economy has continued to expand and diversify and now more closely resembles that of the nearby San Francisco Bay Area. Primary sources of population growth are people migrating from the San Francisco Bay Area seeking lower housing costs, as well as immigration from Asia, Central America, Mexico, Ukraine and the rest of the former Soviet Union.^[1]

Agriculture[link]

The Central Valley is one of the world's most productive agricultural regions. On less than 1 percent of the total farmland in the United States, the Central Valley produces 8 percent of the nation’s agricultural output by value: 17 billion USD in 2002. Its agricultural productivity relies on irrigation from both surface water diversions and groundwater pumping from wells. About one-sixth of the irrigated land in the U.S. is in the Central Valley.^[22]

Virtually all non-tropical crops are grown in the Central Valley, which is the primary source for a number of food products throughout the United States, including tomatoes, almonds,^[23][24] grapes, cotton, apricots, and asparagus.

The top five counties in agricultural sales in the U.S. are in the Central Valley (2007 Data). They are Fresno County (#1 with $3.731 billion in sales), Tulare County (#2 with $3.335 billion), Kern County (#3 with $3.204), Merced County (#4 with $2.330 billion, and Monterey (#5 2.178 billion).^[1][25]

Early farming was concentrated close to the Sacramento-San Joaquin Delta, where the water table was high year round and water transport more readily available, but subsequent irrigation projects have brought many more parts of the valley into productive use. For example, the Central Valley Project was formed in 1935 to redistribute and store water for agricultural and municipal purposes with dams and canals. The even larger California State Water Project was formed in the 1950s and construction continued throughout the following decade.

National Farmworkers Association (NFWA)[link]

It was in the Central Valley, especially in and around Delano, that farm labor leader Cesar Chavez organized Mexican American grape pickers into a union in the 1960s, the National Farmworkers Association (NFWA), in order to improve their working conditions.

Languages[link]

This section requires expansion.

After English and Spanish, Hmong is the third most commonly spoken language.^[26]

Social issues[link]

San Joaquin Valley congestion[link]

Since the 1980s, Bakersfield, Fresno, Visalia, Tracy and Modesto have exploded in both area and population, as housing values along the coast increased. Many people from Los Angeles and the San Francisco Bay Area relocated to growing San Joaquin Valley suburbs in search of more affordable housing while retaining employment outside the Valley. This has led to traffic congestion between their Valley residences and their Bay Area employment with accompanying air pollution. Air pollution became a principal environmental and health concern as long ago as the 1960s, and resulted in the establishment of the California Air Resources Board in 1967.

Highways and infrastructure[link]

The valley in late August, looking at Tracy

Highways Interstate 5 and State Route 99 run, roughly parallel, north-south through the valley, meeting at its north and south ends. Interstate 80 crosses it northeast-southwest from Rocklin to Vacaville.

In addition to highways, the California Aqueduct follows I-5 from Tracy on southwards to Southern California across the Transverse Ranges and the federal Central Valley Project includes numerous facilities between Shasta Dam and the Grapevine. PG&E's and Western Area Power Administration's system of three 500 kV wires (Path 15 and Path 66) run through the valley. Path 26 also runs in the southernmost part of the San Joaquin Valley and is used to transfer power from PG&E service territory to Southern California Edison territory on hot summer days.

BNSF (Burlington Northern Santa Fe Railway) and Union Pacific Railroad both have railway lines in the Central Valley. The BNSF Bakersfield Subdivision runs from Bakersfield to Calwa, four miles (6 km) south of Fresno. From Calwa the BNSF Stockton Subdivision continues to Port Chicago, west of Antioch. The Union Pacific Railroad Martinez Subdivision runs from Port Chicago through Martinez, Richmond and Emeryville to Oakland. The UP's Fresno Subdivision runs from Stockton to Sacramento. Amtrak operates six daily San Joaquins trains over these lines.

California Central Valley portal

References[link]

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2007)

External links[link]

• Central Valley Tourism Association
• CA Central Valley & Foothills, project area of the American Land Conservancy
• Great Valley Center
• Valley Vision

Coordinates: 37°42′22″N 120°59′29″W / 37.70611°N 120.99139°W / 37.70611; -120.99139

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State of California Flag Seal Nickname(s): The Golden State Motto(s): Eureka[1] Official language(s) English Spoken language(s) English (only) 57.6% Spanish 28.2%[2] Demonym Californian Capital Sacramento Largest city Los Angeles Largest metro area Greater Los Angeles Area Area  Ranked 3rd in the U.S.  - Total 163,696 sq mi (423,970 km2)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4.7  - Latitude 32° 32′ N to 42° N  - Longitude 114° 8′ W to 124° 26′ W Population  Ranked 1st in the U.S.  - Total 37,691,912 (2011 est)[3]  - Density 242/sq mi  (93.3/km2) Ranked 11th in the U.S.  - Median household income  US$61,021 (9th) Elevation    - Highest point Mount Whitney[4][5][6][7] 14,505 ft (4421.0 m)  - Mean 2,900 ft  (880 m)  - Lowest point Badwater Basin in Death Valley[5][6] −282[8] ft (-86.0 m) Before statehood California Republic Admission to Union  September 9, 1850 (31st) Governor Jerry Brown (D) Lieutenant Governor Gavin Newsom (D)[9] Legislature California State Legislature  - Upper house California State Senate  - Lower house California State Assembly U.S. Senators Dianne Feinstein (D) Barbara Boxer (D) U.S. House delegation 34 Democrats, 19 Republicans (list) Time zone Pacific: UTC -8/-7 Abbreviations CA Calif. US-CA Website www.ca.gov California State symbols The Flag of California. The Seal of California. Animate insignia Bird(s) California Quail Fish Golden Trout Flower(s) California Poppy Grass Purple Needlegrass Insect California Dogface Butterfly Mammal(s) California grizzly bear (State Animal )[1] Reptile Desert Tortoise Tree California Redwood Inanimate insignia Beverage Wine Colors Blue & Gold Dance West Coast Swing Fossil Sabre-toothed cat Gemstone Benitoite Mineral Native Gold Rock Serpentine Soil San Joaquin Song(s) "I Love You, California" Tartan California State Tartan Route marker(s) State Quarter Released in 2005 Lists of United States state insignia

California (pronounced ⁱ/kælɨˈfɔrnjə/) is a state located on the West Coast of the United States. It is by far the most populous U.S. state,^[10] and the third most extensive (after Alaska and Texas). It is home to the nation's second- and sixth-largest census statistical areas (Los Angeles Metropolitan Area and San Francisco Bay Area), and eight of the nation's fifty most populated cities (Los Angeles, San Diego, San Jose, San Francisco, Fresno, Sacramento, Long Beach and Oakland).^[11] The capital city is Sacramento.

California's diverse geography ranges from the Pacific Coast in the west, to the Sierra Nevada mountains in the east – from the Redwood–Douglas-fir forests of the northwest, to the Mojave Desert areas in the southeast. The center of the state is dominated by Central Valley, a major agricultural area. California contains both the highest and lowest points in the contiguous United States (Mount Whitney and Death Valley), and has the third-longest coastline of all states (after Alaska and Florida). Earthquakes are a common occurrence due to the state's location along the Pacific Ring of Fire: about 37,000 are recorded annually.^[12]

The name California once referred to a large area of North America claimed by Spain that included much of modern-day Southwestern United States and the Baja California peninsula. Beginning in the late 18th century, the area known as Alta California, comprising the California territory north of the Baja Peninsula, was colonized by the Spanish Empire as part of New Spain. In 1821, Alta California became a part of Mexico following its successful war for independence. Shortly after the beginning of the Mexican-American War in 1846, a group of American settlers in Sonoma declared an independent California Republic in Alta California. Though its existence was short-lived, its flag became the precursor for California's current state flag. American victory in the war led to the Treaty of Guadalupe Hidalgo, in which Mexico ceded Alta California to the United States. Western areas of Alta California became the state of California, which was admitted as the 31st state on September 9, 1850.

The California Gold Rush beginning in 1848 led to dramatic social and demographic change, with large scale immigration from the U.S. and abroad and an accompanying economic boom. Key developments in the early 20th century included the emergence of Los Angeles as the center of the American entertainment industry, and the growth of a large, state-wide tourism sector. The late 20th century saw the development of the technology and information sectors, punctuated by the growth of Silicon Valley. California's prosperous agricultural industry also emerged; at least half of the fresh fruit produced in the United States are now cultivated in California, and the state also leads in the production of vegetables.^[13] Other important contributors to its economy include aerospace, education, and manufacturing. If California were a country, it would be the eighth-largest economy in the world^[14] and the 34th most populous nation.

Etymology[link]

Welcome to California sign

The word California originally referred to the entire region composed of the Baja California peninsula of Mexico, the current U.S. states of California, Nevada, and Utah, and parts of Arizona, New Mexico, and Wyoming.

The name California is most commonly believed to have derived from a fictional paradise peopled by Black Amazons and ruled by Queen Calafia.^[15][16] The story of Calafia is recorded in a 1510 work The Adventures of Esplandián, written as a sequel to Amadis de Gaula by Spanish adventure writer Garci Rodríguez de Montalvo.^[17][18][19] The kingdom of Queen Calafia, according to Montalvo, was said to be a remote land inhabited by griffins and other strange beasts, and rich in gold.

Know ye that at the right hand of the Indies there is an island called California, very close to that part of the Terrestrial Paradise, which was inhabited by black women without a single man among them, and they lived in the manner of Amazons. They were robust of body with strong passionate hearts and great virtue. The island itself is one of the wildest in the world on account of the bold and craggy rocks.

— Chapter CLVII of The Adventures of Esplandián^[20]

The name California is the fifth oldest surviving European place-name in the US and was applied to what is now the southern tip of Baja California peninsula as the Island of California by a Spanish expedition led by Diego de Becerra and Fortún Ximénez, who landed there in 1533 at the behest of Hernán Cortés.^{[note 1]}

Geography[link]

Topographic map of California

Aerial view of the California Central Valley

Sierra Nevada

Yosemite National Park

Lake Tahoe

California adjoins the Pacific Ocean to the west, Oregon to the north, Nevada and Arizona to the east, and the Mexican state of Baja California to the south. With an area of 160,000 square miles (414,000 km²), it is the third-largest state in the United States in size, after Alaska and Texas.^[22] If it were a country, California would be the 59th-largest in the world in area.

In the middle of the state lies the California Central Valley, bounded by the coastal mountain ranges in the west, the Sierra Nevada to the east, the Cascade Range in the north and the Tehachapi Mountains in the south. The Central Valley is California's agricultural heartland and grows approximately one-third of the nation's food.^[23][24]

Divided in two by the Sacramento-San Joaquin River Delta, the northern portion, the Sacramento Valley serves as the watershed of the Sacramento River, while the southern portion, the San Joaquin Valley is the watershed for the San Joaquin River; both areas derive their names from the rivers that transit them. With dredging, the Sacramento and the San Joaquin Rivers have remained sufficiently deep that several inland cities are seaports.

The Sacramento-San Joaquin River Delta serves as a critical water supply hub for the state. Water is routed through an extensive network of canals and pumps out of the delta, that traverse nearly the length of the state, including the Central Valley Project and the State Water Project. Water from the Delta provides drinking water for nearly 23 million people, almost two-thirds of the state's population, and provides water to farmers on the west side of the San Joaquin Valley. The Channel Islands are located off the southern coast.

The Sierra Nevada (Spanish for "snowy range") includes the highest peak in the contiguous forty-eight states, Mount Whitney, at 14,505 ft (4421 m).^[4][5][6] The range embraces Yosemite Valley, famous for its glacially carved domes, and Sequoia National Park, home to the giant sequoia trees, the largest living organisms on Earth, and the deep freshwater lake, Lake Tahoe, the largest lake in the state by volume.

To the east of the Sierra Nevada are Owens Valley and Mono Lake, an essential migratory bird habitat. In the western part of the state is Clear Lake, the largest freshwater lake by area entirely in California. Though Lake Tahoe is larger, it is divided by the California/Nevada border. The Sierra Nevada falls to Arctic temperatures in winter and has several dozen small glaciers, including Palisade Glacier, the southernmost glacier in the United States.

About 45 percent of the state's total surface area is covered by forests,^[25] and California's diversity of pine species is unmatched by any other state. California contains more forestland than any other state except Alaska. Many of the trees in the California White Mountains are the oldest in the world; one Bristlecone pine has an age of 4,700 years.

In the south is a large inland salt lake, the Salton Sea. The south-central desert is called the Mojave; to the northeast of the Mojave lies Death Valley, which contains the lowest and hottest place in North America, the Badwater Basin at −282 feet (−86.0 m).^[8] The horizontal distance from the nadir of Death Valley to the summit of Mount Whitney is less than 90 miles (140 km). Indeed, almost all of southeastern California is arid, hot desert, with routine extreme high temperatures during the summer. The southeastern border of California with Arizona is entirely formed by the Colorado River, from which the southern part of the state gets about half of its water.

Along the California coast are several major metropolitan areas, including Greater Los Angeles Area, the San Francisco Bay Area, and the San Diego metropolitan area.

As part of the Ring of Fire, California is subject to tsunamis, floods, droughts, Santa Ana winds, wildfires, landslides on steep terrain, and has several volcanoes. It sees numerous earthquakes due to several faults, in particular the San Andreas Fault.

Climate[link]

Snow on the mountains of Southern California.

Death Valley, in the desert regions of Eastern California

California's climate varies from Mediterranean to subarctic.

Much of the state has a Mediterranean climate, with cool, rainy winters and dry summers. The cool California Current offshore often creates summer fog near the coast. Farther inland, one encounters colder winters and hotter summers.

Northern parts of the state average higher annual rainfall than the south. California's mountain ranges influence the climate as well: some of the rainiest parts of the state are west-facing mountain slopes. Northwestern California has a temperate climate, and the Central Valley has a Mediterranean climate but with greater temperature extremes than the coast. The high mountains, including the Sierra Nevada, have a mountain climate with snow in winter and mild to moderate heat in summer.

The east side of California's mountains produce a rain shadow, creating expansive deserts. The higher elevation deserts of eastern California see hot summers and cold winters, while the low deserts east of the southern California mountains experience hot summers and nearly frostless mild winters. Death Valley, a desert with large expanses below sea level, is considered the hottest location in North America; the highest temperature in the Western Hemisphere, 134 °F (57 °C), was recorded there on July 10, 1913. The lowest temperature in California was −45 °F in 1937 in Boca.

Ecology[link]

California is one of the richest and most diverse parts of the world, and includes some of the most endangered ecological communities. California is part of the Nearctic ecozone and spans a number of terrestrial ecoregions.^[26]

California's large number of endemic species includes relict species, which have died out elsewhere, such as the Catalina Ironwood (Lyonothamnus floribundus). Many other endemics originated through differentiation or adaptive radiation, whereby multiple species develop from a common ancestor to take advantage of diverse ecological conditions such as the California lilac (Ceanothus). Many California endemics have become endangered, as urbanization, logging, overgrazing, and the introduction of exotic species have encroached on their habitat.

Flora and fauna[link]

Giant sequoias in Calaveras Big Trees State Park

Joshua trees in Inyo Mountains above Eureka Valley.

California boasts several superlatives in its collection of flora: the largest trees, the tallest trees, and the oldest trees. California's native grasses are perennial plants.^[27] After European contact, these were generally replaced by invasive species of European annual grasses; and, in modern times, California's hills turn a characteristic golden-brown in summer.^[28]

Because California has the greatest diversity of climate and terrain, the state has six life zones which are the lower Sonoran (desert); upper Sonoran (foothill regions and some coastal lands), transition (coastal areas and moist northeastern counties); and the Canadian, Hudsonian, and Arctic Zones, comprising the state's highest elevations.^[29]

Plant life in the dry climate of the lower Sonoran zone contains a diversity of native cactus, mesquite, and paloverde. The Joshua tree is found in the Mojave Desert. Flowering plants include the dwarf desert poppy and a variety of asters. Fremont cottonwood and valley oak thrive in the Central Valley. The upper Sonoran zone includes the chaparral belt, characterized by forests of small shrubs, stunted trees, and herbaceous plants. Nemophila, mint, phacelia, viola, and the California poppy (Eschscholtzia californica) – the state flower – also flourish in this zone, along with the lupine, more species of which occur here than anywhere else in the world.^[29]

The transition zone includes most of California's forests with the redwood (Sequoia sempervirens) and the "big tree" or giant sequoia (Sequoia gigantea), among the oldest living things on earth (some are said to have lived at least 4,000 years). Tanbark oak, California laurel, Sugar Pine, madrona, broad-leaved maple, and Douglas-fir also grow here. Forest floors are covered with swordfern, alumnroot, barrenwort, and trillium, and there are tickets of huckleberry, azalea, elder, and wild currant. Characteristic wild flowers include varieties of mariposa, tulip, and tiger and leopard lilies.^[30]

The high elevations of the Canadian zone allow the Jeffrey Pine, red fir, and Lodgepole Pine to thrive. Brushy areas are abundant with dwarf manzanita and ceanothus; the unique Sierra puffball is also found here. Right below the timeberline, in the Hudsonian zone, the whitebark, foxtail, and silver pines grow. At about 10,500 ft (3,200 m), begins the Arctic zone, a treeless region whose flora include a number of wildflowers, including Sierra primrose, yellow columbine, alpine buttercup, and alpine shooting star.^[29][31]

Common plants that have been introduced to the state include the eucalyptus, acacia, pepper tree, geranium, and Scotch broom. The species that are federally classified as endangered are the Contra Costa wallflower, Antioch Dunes evening primrose, Solano Grass, San Clemente Island larkspur, salt marsh bird's beak, McDonald's rock-cress, and Santa Barbara Island Liveforever. As of December 1997^[update], 85 plant species were listed as threatened or endangered.^[29]

In the deserts of the lower Sonoran zone, the mammals include the jackrabbit, kangaroo rat, squirrel, and opossum. Common birds include the owl, roadrunner, Cactus Wren, and various species of hawk. The area's reptilian life include the sidewinder viper, desert tortoise, and horned toad. The upper Sonoran zone boasts mammals such as the antelope, brown-footed woodrat, and Ring-tailed Cat. Birds unique to this zone are the California thrasher, bushtit, and California Condor.^{[29][32][33][34]}

In the transition zone, there are Colombian Black-tailed Deer, black bears, gray foxes, cougars, bobcats, and Roosevelt elk. Reptiles such as the garter snakes and rattlesnakes inhabit the zone. In addition, amphibians such as the water puppy and redwood salamander are common too. Birds such as the kingfisher, chickadee, towhee, and hummingbird thrive here as well.^[29][35]

The Canadian zone mammals include the Mountain Weasel, Snowshoe Hare, and several species of chipmunks. Conspicuous birds include the blue-fronted jay, Sierra chickadee. Sierra hermit thrush, water ouzel, and Townsend's solitaire. As one ascends into the Hudsonian zone, birds become scarcer. While the Sierra rosy finch is the only bird native to the high Arctic region, other bird species such as the hummingbird and Clark's Nutcracker. Principal mammals found in this region include the Sierra coney, White-tailed Jackrabbit, and the Bighorn Sheep. As of April 2003^[update], the Bighorn Sheep was listed as endangered by the US Fish and Wildlife Service. The fauna found throughout several zones are the mule deer, coyote, mountain lion, Northern Flicker, and several species of hawk and sparrow.^[29]

Aquatic life in California thrives, from the state's mountain lakes and streams to the rocky Pacific coastline. Numerous trout species are found, among them rainbow, golden, and Tahoe. Migratory species of salmon are common as well. Deep-sea life forms include sea bass, yellowfin tuna, barracuda, and several types of whale. Native to the cliffs of northern California are seals, sea lions, and many types of shorebirds, including migratory species.^[29]