California is aU.S. state on the western coast ofNorth America. Covering an area of 163,696 sq mi (423,970 km2), California is among the most geographically diverse states. TheSierra Nevada, the fertile farmlands of theCentral Valley, and the aridMojave Desert of the south are some of the geographic features of thisU.S. state. It is home to some of the world's most exceptional trees: the tallest (coast redwood), most massive (Giant Sequoia), and oldest (bristlecone pine). It is also home to both the highest (Mount Whitney) and lowest (Death Valley) points in the48 contiguous states.
The state is generally divided intoNorthern andSouthern California, although the boundary between the two is not well defined. San Francisco is decidedly a Northern California city and Los Angeles is a Southern California one but areas in between do not often share their confidence in geographic identity. TheUS Geological Survey defines the geographic center of California about 7.1 miles (11.4 km) driving distance from theUnited States Forest Service office in the community ofNorth Fork. Earth scientists typically divide the state into eleven geomorphic provinces with clearly defined boundaries. They are, from north to south, theKlamath Mountains, theCascade Range, theModoc Plateau, theBasin and Range, theCoast Ranges, theCentral Valley, theSierra Nevada, theTransverse Ranges, theMojave Desert, thePeninsular Ranges, and theColorado Desert.
The boundaries of California were defined by Spanish claims ofMexico, as part of the province ofAlta California. The northern boundary of Spanish claims was set at 42 degrees latitude by theAdams–Onis Treaty of 1819.[1] The states of Nevada and Utah, also originally part of Alta California, also use that line for their northern boundaries. The southern boundary, between California and Mexico, was established by theTreaty of Guadalupe Hidalgo that ended theMexican–American War in 1848. The line is about 30 miles (48 km) north of the former Alta California southern boundary. The eastern boundary consists of two straight lines: a north–south line from the northern border to the middle ofLake Tahoe, and a second line angling southeast to theColorado River. From that point, 14 miles (23 km) south-southwest ofDavis Dam onLake Mohave, the southeast boundary follows theColorado River to the international border west ofYuma, Arizona. The eastern and south-eastern boundaries were decided upon during the debates of theCalifornia Constitutional Convention in 1849.
Northern California usually refers to the state's northernmost 48 counties.
The main population centers of Northern California includeSan Francisco Bay Area (which includes the cities ofSan Francisco,Oakland, and the largest city of the region,San Jose), andSacramento (the state capital) as well asits metropolitan area. It also containsredwood forests, along with theSierra Nevada includingYosemite Valley andLake Tahoe,Mount Shasta (the second-highest peak in theCascade Range afterMount Rainier inWashington), and the northern half of theCentral Valley, one of the world's most productive agricultural regions. The climate can be generally characterized by itsmarine to warmMediterranean climates along the coast, to a somewhat continental Mediterranean climate in the valley to alpine climate zones in the high mountains. Apart from theSan Francisco Bay Area andSacramento metropolitan areas (and some other cities in the Central Valley), it is a region of relatively low population density. Northern California's economy is noted for being the de facto world leader in industries such as high technology (both software andsemiconductor), as well as being known forclean power, biomedical, government, and finance.
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TheKlamath Mountains are arange in northwest California and southwest Oregon, the highest peak beingMount Eddy inTrinity County, California, at 9,037 feet (2,754 m).[2] The range has a varied geology, with substantial areas ofserpentine andmarble. The climate is characterized by moderately cold winters with heavy snowfall and warm, very dry summers with limited rainfall.[3] As a consequence of the geology, the mountains have a unique flora, including several endemic or near-endemic species, such asLawson's Cypress (Chamaecyparis lawsoniana) andFoxtail Pine (Pinus balfouriana).Brewer's Spruce(Picea breweriana) andKalmiopsis(Kalmiopsis leachiana) are relict species, remaining since thelast ice age.[4]
TheCascade Range is a mountainous region stretching from theFraser River inBritish Columbia, Canada down to south ofLassen Peak, California.[5] The Cascades (as they are called for short) are part of the PacificRing of Fire, the ring of volcanoes around the Pacific Ocean.[6] All of the known historic eruptions in the contiguous United States have been from either Cascade volcanoes or nearMono Lake.[7]: 7 Lassen Peak was the last Cascade volcano to erupt in California, from 1914 to 1921. Lassen is the most southerly active volcano of the Cascade chain.[8]
This region is located in the northeastern section of the state borderingOregon andNevada, mostly north of the Central Valley and the Sierra Nevada mountain range. The area is centered onMount Shasta, near theTrinity Alps. Mount Shasta is a dormant volcano, but there is some evidence that it erupted in the 18th century.[7]: 99
In the northeast corner of the state lies theModoc Plateau, an expanse oflava flows that formed a million years ago and now lie at an altitude of 4,000 to 5,000 feet (1,200 to 1,500 m).[9] The plateau has manycinder cones,juniper flats,pine forests, and seasonal lakes.[10] The plateau lies between the Cascade Range to the west and theWarner Mountains to the east.[9] TheLost River watershed drains the north part of the plateau, while southern watersheds either collect in basin reservoirs or flow intoBig Sage Reservoir and thence to thePit River.
Nine percent of the plateau is protected as reserves or wilderness areas,[9] such as theModoc National Wildlife Refuge.[11] The plateau supports large herds ofmule deer (Odocoileus hemionus),Rocky Mountain Elk (Cervus canadensis), andpronghorn (Antilocapra americana).[9] Herds of wild horses and livestock grazing have altered the original high desert ecosystem of the plateau.[9]
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To the east of the Sierra is theBasin and Range geological province, which extends intoNevada. The Basin and Range is a series of mountains and valleys (specificallyhorsts andgrabens), caused by the extension of the Earth's crust.[12] One notable feature of the Basin and Range isMono Lake, which is the oldest lake inNorth America.[13] The Basin and Range also contains theOwens Valley, the deepest valley in North America (more than 10,000 feet (3 km) deep, as measured from the top of Mount Whitney).[14]
In the eastern part of the state, below the Sierra Nevada, there is a series of dry lake beds that were filled with water during the last ice age (fed by ice melt fromalpine glaciers but never directly affected byglaciation; seepluvial).[15] Many of these lakes have extensiveevaporite deposits that contain a variety of differentsalts. In fact, the salt sediments of many of these lake beds have beenmined for many years for various salts, most notablyborax (this is most famously true forOwens Lake andDeath Valley).
In this province reside theWhite Mountains, which are home to the oldest living organism in the world, thebristlecone pine[16]
To the west of the Central Valley lies theCoast Ranges, including theDiablo Range, just east ofSan Francisco, and theSanta 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 theircoast redwoods, thetallest trees on earth, which live within the range of the coastalfog.
California's geography is largely defined by its central feature—theCentral Valley, a huge, fertilevalley between the coastal mountain ranges and theSierra Nevada. The northern part of the Central Valley is called theSacramento Valley, after its main river, and the southern part is called theSan Joaquin Valley/ˌsænwɑːˈkiːn/, after its main river. The whole Central Valley is watered by mountain-fed rivers (notably theSan Joaquin,Kings, andSacramento) that drain to theSan Francisco Bay system. The rivers are sufficiently large and deep that several inland cities, notablyStockton, andSacramento are seaports.
The southern tip of the valley has interior drainage and thus is not technically part of the valley at all.Tulare Lake, with an area of 570 square miles (1,476 km2), once filled much of the area. In modern times, it is usually adry lake and partially covered with agricultural fields. The lake reappears during unusually high levels of rainfall or snow melt such as the winter of 2022 and early spring of 2023.
In the east of the state lies theSierra Nevada, which runs north–south for 400 miles (640 km). The highest peak in the contiguous United States,Mount Whitney at 14,505 feet (4.42 km), 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, a rare combination of rugged variety and pleasant weather. The famousYosemite Valley lies in the Central Sierra. The large, deep freshwaterLake Tahoe lies to the North of Yosemite. The Sierra is also home to theGiant Sequoia, the most massive trees on Earth.
The most famous hiking and horse-packing trail in the Sierra is theJohn Muir Trail, which goes from the top of Mt. Whitney to Yosemite valley. This is part of thePacific Crest Trail that goes fromMexico toCanada. The three major national parks in this province areYosemite National Park,Kings Canyon National Park, andSequoia National Park.
The term Southern California usually refers to the ten southernmost counties which closely match the lower one-third of California's span of latitude. This definition coincides neatly with the county lines at 35° 47′ 28″ north latitude, which form the northern borders ofSan Luis Obispo,Kern, andSan Bernardino counties. Geographically, Southern California is separated from the north by theTransverse Ranges and theSierra Nevada range, creating a significant biological barrier. Historically, this barrier also limited human movement and commerce.[17][18][19]
Southern California consists of a heavily developedurban environment, home to some of the largesturban areas in the state, along with vast areas that have been left undeveloped. With over 22 million people, roughly 60% of California's population resides in Southern California. It is the second-largest urbanized region in the United States, second only to theWashington/Philadelphia/New York/BostonNortheastern Megalopolis. Where these cities are dense, with major downtown populations and significant rail and transit systems, much of Southern California is famous for its large, spread-out,suburban communities and use of automobiles and highways. The dominant areas areLos Angeles,Orange County,San Diego, andRiverside-San Bernardino, each of which is the center of its respective metropolitan area, composed of numerous smaller cities and communities. The urban area is also host to an international metropolitan region in the form ofSan Diego–Tijuana, created by the urban area spilling over into Baja California.
Southern California is noted for industries including the film industry, residential construction, entertainment industry, and military aerospace. Other industries include software, automotive, ports, finance, tourism, biomedical, and regional logistics.
Southern California is separated from the rest of the state by the east–west trendingTransverse Ranges. The Transverse Ranges include a series of east–west trending mountain ranges that extend fromPoint Conception, at the western tip ofSanta Barbara County, eastward (and a bit south) to the east end of theSan Jacinto Mountains in westernRiverside County.
TheSanta Ynez Mountains make up the westernmost ranges, extending from Point Conception to theVentura River just west-northwest ofOjai inVentura County.Pine Mountain Ridge, Nordhoff Ridge–Topatopa Mountains, Rincon Peak–Red Mountain, Sulphur Mountain, Santa Paula Ridge, South Mountain–Oat Mountain–Santa Susana Mountains,Simi Hills,Conejo Mountains–Santa Monica Mountains are all part of the Western Transverse Ranges in Ventura and western Los Angeles counties. The Transverse Ranges also include theTehachapi Mountains, which separate the Central Valley from theMojave Desert.
TheLiebre Mountains occupy the northwest corner ofLos Angeles County, and represent a northwestern extension of theSan Gabriel Mountains, both on thePacific plate side of theSan Andreas Fault. The fault divides the San Gabriel Mountains from theSan Bernardino Mountains further to the east inSan Bernardino County.
Urban Southern California occupies the valleys between theSanta Susana Mountains,Santa Monica Mountains andSan Gabriel Mountains, which range from the Pacific Coast, eastward over 100 miles (160 km), to theSan Bernardino Mountains, north ofSan Bernardino. The highest point of the range isMount San Gorgonio at 11,499 feet (3,505 m). The San Gabriel Mountains haveMount Wilson observatory, where theredshift was discovered in the 1920s.
It is possible tosurf in thePacific Ocean andski on a mountain during the same winter day inSouthern California.
There are harshdeserts in the Southeast of California. These deserts are caused by a combination of the cold offshore current, which limits evaporation, and therain 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. When the wind blows from inland, the resulting hot drykatabatic winds are called theSanta Ana Winds.
TheMojave Desert is bounded by the peninsular Tehachapi Mountains on the Northwest, together with the San Gabriel and the San Bernardino Mountains on the Southwest. These Western boundaries are quite distinct, forming the dominant pie-slice shapedAntelope Valley in Southern California. The outlines of this valley are caused by the two largest faults in California: theSan Andreas and theGarlock. The Mojave Desert extends Eastward into the State ofNevada. The Mojave Desert receives less than 6 inches (150 mm) of rain a year and is generally between 3,000 and 6,000 feet (1,000 and 2,000 m) of elevation. Areas such as the Antelope Valley desert which is a high desert received snow each year, in the past it could snow 2–3 times a year; however, recently snow level has declined significantly to once a year or less. Most of the towns and cities in the California portion of the Mojave are relatively small, except forPalmdale andLancaster. However, some are quite famous likeBarstow, a popular stop on the famousU.S. Route 66. The Mojave Desert also contains the lowest, hottest place in theAmericas:Death Valley, where temperature normally approaches 120 °F (49 °C), in late July and early August.
The southernmost mountains of California are thePeninsular Ranges, which are east ofSan Diego and continue intoBaja California (Mexico) in theSierra San Pedro Martir. The Peninsular Ranges contain theLaguna Mountains, theSan Jacinto Mountains, theSanta Rosa Mountains, theSanta Ana Mountains and thePalomar Mountain Range, notable for its famousPalomar observatory.San Jacinto Peak's eastern shoulder has a cable tram that runs from the desert floor to nearly the top of the mountain where riders can set offhiking or gocross-country skiing.
To the east of the peninsular ranges lie theColorado andSonoran Deserts, which extend intoArizona and Mexico.
The ground elevation is generally lower and in some areas was compressed downward, therefore the easternCoachella andImperial Valleys north of theU.S.-Mexican border are below sea level. The lowest community in the U.S. isCalipatria, California, at 180 feet (55 m) below sea level.[20]
One feature of the desert is theSalton Sea, an inland lake that was formed in 1905 when a swollenColorado River breached acanal near theU.S.-Mexico border and flowed into theSalton Sink (Salton Basin) for almost two years. Today, the Salton Sea, a new version of historicLake Cahuilla, remains as California's largest lake.
ThePacific Ocean lies to the west of California. Owing to the long length of the state, Sea temperatures generally range from 50 °F (10 °C) in the northernmost parts during winter to 70 °F (21 °C) in the south coast during summer. The lower seasonal temperature variance compared to the waters of the East Coast is because ofup-welling deep waters with dissolved nutrients. Therefore, sea life in and around California has examples of both Arctic and tropical,biotopes, leaning more towards the latter in the south coast and vice versa. The sea off California is remarkably fertile, a murky green filled with a massive variety of fish, rather than the clear dead blue of most tropical seas. Before 1930, there was an extremely valuablesardine (herring) fishery offMonterey, but this was depleted, an event later famous as the background toJohn Steinbeck'sCannery Row.
California's coastline is about 840 miles long, thethird longest coastline in the United States afterAlaska andFlorida.
Earthquakes occur due tofaults that run the length of the Pacific coast, the largest being theSan Andreas Fault. Major historical earthquakes include, with the magnitudes listed:
Coastal cities are vulnerable totsunamis from locally generated earthquakes as well as those elsewhere in the PacificRing of Fire. TheGreat Chilean earthquake tsunami (1960) killed one person and caused $500,000 to $1,000,000 of damage inLos Angeles, damaged harbors in many coastal cities, and flooded streets inCrescent City.[21] Waves from the AlaskanGood Friday earthquake of 1964 killed twelve people in Crescent City and caused damage as far south as Los Angeles. USGS has released the UCERFCalifornia earthquake forecast which models earthquake occurrence in California.
California is also home to severalvolcanoes, includingLassen Peak, which erupted in 1914 and 1921, andMount Shasta.
California, when only partially explored by the Spanish, was once thought to be an island, as when the southernBaja California peninsula is approached from theGulf of California the land appears to the west. It is expected, through the motions ofplate tectonics that the sea floor spreading now acting in the Gulf of California (also known as the Sea of Cortez) will eventually extend through Southern California and along the San Andreas fault to belowSan Francisco, finally forming a long island in less than 150 million years. (For comparison, this is also the approximate age of theAtlantic Ocean.) Predictions suggest that this island will eventually collide withAlaska after an additional 100 million years.
California's climate varies widely, fromarid tosubarctic, depending onlatitude,elevation, and proximity to the coast. Coastal and Southern parts of the state have aSubtropicalMediterranean climate, with somewhat rainy winters and dry summers. The influence of theocean generally moderates temperature extremes, creating warmer winters and substantially cooler summers, especially along the coastal areas.
The state is subject tocoastal storms during the winter. Eastern California is subject to summertime thunderstorms caused by theNorth American monsoon. Dry weather during the rest of the year produces conditions favorable towildfires.California hurricanes occur less frequently than their counterparts on theAtlantic Ocean. Higher elevations experiencesnowstorms in the winter months.
Floods are occasionally caused by heavy rain, storms, and snowmelt. Steep slopes and unstable soil make certain locations vulnerable tolandslides in wet weather or during earthquakes.
37°9′58″N119°26′58″W / 37.16611°N 119.44944°W /37.16611; -119.44944 (Center of California)
