Great Basin | |
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 Relief map with Great Basin overlay | |
| Coordinates:40°40′N117°40′W / 40.667°N 117.667°W /40.667; -117.667[1] | |
| Location | United States, Mexico |
| Area | |
| • Total | 209,162 sq mi (541,730 km2)[2] |
| Highest elevation | 14,505 ft (4,421 m) (Mount Whitney summit) |
TheGreat Basin is the largest area of contiguousendorheic watersheds, those with no outlets to the ocean, inNorth America. It spans nearly all ofNevada, much ofUtah, and portions ofCalifornia,Idaho,Oregon,Wyoming, andBaja California. It is noted for both its arid climate and thebasin and range topography that varies from the North American low point atBadwater Basin inDeath Valley to the highest point of thecontiguous United States, less than 100 miles (160 km) away at the summit ofMount Whitney. The region spans severalphysiographic divisions,biomes,ecoregions, anddeserts.
The term "Great Basin" is applied tohydrographic,[3][4]: 11 biological,[3]floristic,[4]: 21 physiographic,[4]: 14 topographic,[3] andethnographic geographic areas.[4]: 34 The name was originally coined byJohn C. Frémont, who, based on information gleaned fromJoseph R. Walker as well as his own travels, recognized the hydrographic nature of the landform as "having no connection to the ocean".[4]: 8–9 The hydrographic definition is the most commonly used,[3] and is the only one with a definitive border. The other definitions yield not only different geographical boundaries of "Great Basin" regions but regional borders that vary from source to source.[4]: 11
TheGreat Basin Desert is defined by plant and animal communities, and, according to theNational Park Service, its boundaries approximate the hydrographic Great Basin but exclude the southern "panhandle".[3]
TheGreat Basin Province was defined by botanistArmen Takhtajan to extend well beyond the boundaries of the hydrographically defined Great Basin: it includes theSnake River Plain, theColorado Plateau, theUinta Basin, and parts ofArizona north of theMogollon Rim.[5]
TheGreat Basin physiographic section is a geographic division of theBasin and Range Province defined byNevin Fenneman in 1931.[6] TheUnited States Geological Survey adapted Fenneman's scheme in theirPhysiographic division of the United States.[7] The "section" is somewhat larger than the hydrographic definition.
TheGreat Basin culture area, orindigenous peoples of the Great Basin, is a culturalclassification of indigenous peoples of the Americas and acultural region located between the Rocky Mountains and the Sierra Nevada. The culture area covers approximately 400,000 sq mi (1,000,000 km2),[8] or just less than twice the area of the hydrographic Great Basin.
The hydrographic Great Basin is a 209,162-square-mile (541,730 km2) area that once drained internally. All precipitation in the region evaporated, sank underground or flowed into lakes (mostly saline). As observed by Fremont, creeks, streams, or rivers find no outlet to either theGulf of Mexico or thePacific Ocean. The region is bounded by theWasatch Mountains to the east, theSierra Nevada andCascade Ranges to the west, and the Snake River Basin to the north. The south rim is less distinct. The Great Basin includes most ofNevada, half ofUtah, substantial portions ofOregon andCalifornia, and small areas ofIdaho,Wyoming, andBaja California, Mexico. The term "Great Basin" is slightly misleading; the region comprises many small basins. TheGreat Salt Lake,Pyramid Lake, and theHumboldt Sink are a few of the "drains" in the Great Basin.[3] TheSalton Sink is another closed basin within the Great Basin.[9]
TheGreat Basin Divide separates the Great Basin from the watersheds draining to the Pacific Ocean. The southernmost portion of the Great Basin is the watershed area of theLaguna Salada. The Great Basin's longest and largest river is theBear River of 350 mi (560 km),[10] and the largest single watershed is theHumboldt River drainage of roughly 17,000 sq mi (44,000 km2). Most Great Basin precipitation is snow, and the precipitation that neither evaporates nor is extracted for human use will sink intogroundwateraquifers, while evaporation of collected water occurs fromgeographic sinks.[11]Lake Tahoe, North America's largestalpine lake,[12] is part of the Great Basin's centralLahontan subregion.
The hydrographic Great Basin contains multiple deserts andecoregions, each with its own distinctive set of flora and fauna.[3] The ecological boundaries and divisions in the Great Basin are unclear.[15]
The Great Basin overlaps four different deserts: portions of thehotMojave andColorado (a region within theSonoran Desert) Deserts to the south, and thecoldGreat Basin andOregon High Deserts in the north. The deserts can be distinguished by their plants: theJoshua tree andcreosote bush occur in the hot deserts, while the cold deserts have neither. The cold deserts are generally higher than the hot and have more even spread of precipitation throughout the year.[16]
The climate and flora of the Great Basin are strongly dependent on elevation; as the elevation increases, the temperature decreases and precipitation increases. Because of this, forests can occur at higher elevations.Utah juniper/single-leaf pinyon (southern regions) andmountain mahogany (northern regions) form openpinyon-juniper woodland on the slopes of most ranges. Stands oflimber pine and Great Basin bristlecone pine (Pinus longaeva) can be found in some of the higher ranges. Inriparian areas with dependable water cottonwoods (Populus fremontii) and quaking aspen (Populus tremuloides) groves exist.
Because the forest ecosystem is distinct from a typical desert, some authorities, such as theWorld Wildlife Fund, separate the mountains of the Great Basin desert into their own ecoregion: theGreat Basin montane forests.[17] Many rare and endemic species occur in this ecoregion, because the individual mountain ranges are isolated from each other. During theLast Glacial Period, the Great Basin was wetter. As it dried during theHolocene epoch, some species retreated to thehigher isolated mountains and have high genetic diversity.[17]
Other authorities divide the Great Basin into different ecoregions, depending on their own criteria.Armen Takhtajan defined the "Great Basin floristic province". The U.S.Environmental Protection Agency divides the Great Basin into three ecoregions roughly according to latitude: theNorthern Basin and Range ecoregion, theCentral Basin and Range ecoregion, and theMojave Basin and Range ecoregion.
Great Basin wildlife includespronghorn,mule deer,mountain lion, andlagomorphs such asblack-tailed jackrabbit anddesert cottontail and thecoyotes that prey on them.Packrats,kangaroo rats and other small rodents are also common, and are predominantly nocturnal.Elk andbighorn sheep are present but uncommon. Smalllizards such as theGreat Basin fence lizard,longnose leopard lizard andhorned lizard are common, especially in lower elevations.Rattlesnakes andgopher snakes are also present. TheInyo Mountains salamander is endangered. Shorebirds such asphalaropes andcurlews can be found in wet areas.American white pelicans are common atPyramid Lake.Golden eagles are also very common in the Great Basin.[18]Mourning dove,western meadowlark,black-billed magpie, andcommon raven are other common bird species.
Twoendangered species of fish are found in Pyramid Lake: theCui-uisucker fish (endangered 1967) and theLahontan cutthroat trout (threatened 1970).[19]
Largeinvertebrates includetarantulas (genusAphonopelma) andMormon crickets. Exotic species, includingchukar,grey partridge, andHimalayan snowcock, have been successfully introduced to the Great Basin, although the latter has only thrived in theRuby Mountains.Cheatgrass, aninvasive species which was unintentionally introduced, forms a critical portion of their diets.Feralhorses (mustangs) and feralburros are highly reproductive, and ecosystem-controversial, alien species. Most of the Great Basin isopen range and domesticcattle andsheep are widespread.
The Great Basin includes valleys, basins, lakes and mountain ranges of theBasin and Range Province.[20]
Thebasin and range topography is the result of extension and thinning of thelithosphere, which is composed ofcrust andupper mantle. Extensional environments like the Basin and Range are characterized bylistric normal faulting, or faults that level out with depth. Opposing normal faults link at depth producing ahorst andgraben geometry, where horst refers to the upthrown fault block and graben to the down dropped fault block.[21][22]
Sediment build-up over thousands of years filled the down-faulted basins between ranges and created relatively flatlacustrine plains fromPleistocene lake beds of the Great Basin.[23] For example, after forming about 32,000years ago,Lake Bonneville overflowed about 14,500 years ago in theBonneville Flood throughRed Rock Pass and lowered to the "Provo Lake"[24] level (theGreat Salt Lake,Utah Lake,Sevier Lake,Rush Lake, andLittle Salt Lake remain).[25]Lake Lahontan,Lake Manly, andLake Mojave were similarPleistocene lakes.
The Great Basinphysiographic section of the Basin and Range Province contains the Great Basin, but extends into easternOregon, southernIdaho, and theColorado River watershed and the northwest corner ofArizona.[26] The Basin and Range region is the product of geological forces stretching the Earth's crust, creating many north–south trending mountain ranges. These ranges are separated by flat valleys or basins. These hundreds of ranges make Nevada the most mountainous state in the country.[3]
The Great Basin's two most populous metropolitan areas are theReno-Sparks metropolitan area to the west and theWasatch Front to the east (with the latter being significantly more populous than the former). The region between these two areas is sparsely populated, but includes the smaller cities ofElko,Ely,Wendover,West Wendover, andWinnemucca. To the north are; in CaliforniaSusanville, in OregonBurns andHines, in IdahoMalad and in WyomingEvanston. To the south areCedar City,Tonopah, andBishop and the very southern area of the basin has the communities ofPahrump,Palmdale,Victorville, andPalm Springs.Interstate Highways traversing the Great Basin areInterstate 80 (I-80) andI-15, andI-70 andI-84 have their respective endpoints within its boundaries. Other major roadways areU.S. Route 6 (US 6),US 50,US 93,US 95 andUS 395. The section of US 50 betweenDelta, Utah, andFallon, Nevada, is nicknamed "The Loneliest Road in America",[27] andNevada State Route 375 is designated the "Extraterrestrial Highway".[28] The Great Basin is traversed by several rail lines including theUnion Pacific Railroad'sOverland Route (Union Pacific Railroad) through Reno andOgden,Feather River Route,Central Corridor andLos Angeles and Salt Lake Railroad.
There has been a succession ofindigenous peoples of the Great Basin.Paleo-Indian habitation by theGreat Basin tribes began as early as 10,000 B.C. .[29]Archaeological evidence of habitation sites along the shore ofLake Lahontan date from the end of the ice age when its shoreline was approximately 500 feet (150 m) higher along the sides of the surrounding mountains. The Paleo-Indians were mainly hunters and hunted bison, the extinct mammoth, and extinct ground sloth. For housing, since they followed the animals they were hunting, they had no permanent villages.[30]
The next group to live in the area was the Great Basin Desert Archaic, from approximately 9,000 to 1,500 years ago. They hunted animals like mule deer and antelope and gathered onions, wild rye, andpinyon pine nuts. Then, from 1,500 to 700 years ago, theFremont lived in the area. Unlike the Paleo-Indians, who moved around to follow bison herds, the Fremont built small villages and grew crops like corn and squash.
Seven hundred years ago, the Shoshone inhabited the area after the Fremont. They were hunter-gathers and lived in temporary homes to be able to follow animal herds and collect plants. Now, Shoshone descendants live in nearby areas.[30] Other tribes in the area included theUte,Mono, andNorthern Paiute. All of the tribes speak a language in theNumic language group.
To close a 1951 Indian Claims Commission case, theWestern Shoshone Claims Distribution Act of 2004 established the United States payment of $117 million to the Great Basin tribefor the acquisition of 39,000 square miles (100,000 km2).[citation needed]
European exploration of the Great Basin occurred during the 18th centurySpanish colonization of the Americas. The first immigrant American to cross the Great Basin from theSierra Nevada wasJedediah Strong Smith in 1827.[31]Peter Skene Ogden of the BritishHudson's Bay Company explored the Great Salt Lake and Humboldt River regions in the late 1820s, following the eastern side of the Sierra Nevada to the Gulf of California.[32]Benjamin Bonneville explored the northeast portion during an1832 expedition. The United States had acquired claims to the territory north of the42nd parallel via the 1819Adams–Onís Treaty with Spain and 1846Oregon Treaty with Britain. The US gained claims to most of the rest of the Great Basin via the 1848Mexican Cession. The first non-indigenous settlement was in 1847 in the Great Salt Lake Valley, leading to the first American religious settlement effort of theMormon provisionalState of Deseret in 1849 in present-day Utah and northern Nevada. Later settlements were connected with the eastern regions of the 1848California Gold Rush, with its immigrants crossing the Great Basin on theCalifornia Trail along Nevada'sHumboldt River toCarson Pass in the Sierras. TheOregon Territory was established in 1848 and theUtah Territory in 1850.
In 1869 theFirst transcontinental railroad was completed atPromontory Summit in the Great Basin.[33] Around 1902, theSan Pedro, Los Angeles and Salt Lake Railroad was constructed in the lower basin and Mojave Desert forCalifornia-Nevada rail service to Las Vegas, Nevada.
The climate varies throughout the Great Basin by elevation, latitude, and other factors. Higher elevations tend to be cooler and receive more precipitation. The western areas of the basin tend to be drier than the eastern areas because of therain shadow of theSierra Nevada. Most of the basin experiences a semi-arid or arid climate with warm summers and cold winters. However, some of the mountainous areas in the basin are high enough in elevation to experience analpine climate. Due to the region's altitude and aridity, most areas in the Great Basin experience a substantialdiurnal temperature variation.
This article incorporatespublic domain material fromWhat is the Great Basin?.National Park Service. Retrieved2015-07-14.
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