Great Basin

 

semiarid, N section of the Basin and Range province, the intermontane plateau region of W United States and N Mexico. Lying mostly in Nevada and extending into California, Oregon, Idaho, and Utah, it is bordered by the Sierra Nevada on the west, the Columbia Plateau on the north, the Rocky Mts. on the northeast, the Colorado Plateau on the east, and the Mojave Desert on the south.

Land

The region is a complex topographic basin, the surface of which is broken by numerous fault-block mountains, trending mostly north-south and rising sharply in places to more than 10,000 ft (3,048 m) above dry, sediment-floored basins. Death Valley, 282 ft (86 m) below sea level, is the lowest basin; it is also the hottest (134°F/57°C in the shade is the highest temperature recorded) and one of the driest (less than 3 in./7.6 cm of rain annually) parts of North America. Throughout the Great Basin rainfall is limited (2–20 in./5.1–51 cm annually) and sporadic.

The region was recognized as an area of interior drainage by J. C. Frémont, who explored (1843–45) and named it. The rivers of the region have no outlet to the sea; they either dry up as they cross the parched terrain, like the Humboldt, or empty into large lakes or into playas that temporarily fill with water after heavy rain. Klamath and Utah lakes contain freshwater; most other lakes are brackish or salty. The lakes are remnants of a much larger system of ancient lakes that occupied the region during the Pleistocene epoch: Great Salt, Sevier, and Utah lakes are remnants of glacial Lake Bonneville (see under Bonneville Salt Flats); North Carson, South Carson, Walker, Honey, Pyramid, and Winnemucca are remnants of glacial Lake Lahontan; and glacial Lake Manly is thought to have occupied Death Valley.

Economy

Although Nevada and Utah experienced significant growth in the 1970s and 80s, the Great Basin remains one of the least populated areas of the United States. In recent decades, its traditional economic activities, mining and ranching, have been superseded by manufacturing and tourism. In addition, several military installations, including a nuclear testing site in Nevada, have been established since the 1950s and a concentration of aerospace, defense, and electronics firms has sprung up around them.

The mining industry in the Great Basin traces its roots to the 1850s, when gold and silver were discovered in Death Valley; the discovery of silver at the Comstock Lode near Virginia City, Nev., in 1859 attracted a new influx of settlers. The output of gold from mines in both Nevada and Utah remains high. Mercury and barite are also mined in Nevada; in Utah, beryllium, uranium, molybdenum, and silver are mined. Copper mines, formerly the mainstay of the regional economy, began to decline in the 1970s and have largely fallen into disuse. A variety of commercial salts are processed at chemical plants near the Great Salt Lake. Intensive forms of cattle production, based on irrigated feed crops, are concentrated along the Humboldt and Reese rivers and along streams draining into the margins of the Great Basin from the Wasatch Mts. and the Sierra Nevada. Great Basin National Park (77,180 acres/31,258 hectares) is located in the South Snake Range of E Nevada. It has exceptional scenic and geologic attractions, including Lehman Caves and Wheeler Peak (the highest point in the park, with Nevada's only glacier and groves of bristlecone pines, the oldest living trees). It was designated a national park in 1986. See National Parks and Monuments (table).

Bibliography

See W. D. Thornbury, Regional Geomorphology of the United States (1965); J. McPhee, Basin and Range (1981); W. Fiero, Geology of the Great Basin (1986); G. G. Cline, Exploring the Great Basin (1988).

The Great Basin is a large, arid region of the western United States. Its boundaries depend on how it is defined. Its most common definition is the contiguous watershed, roughly between the Wasatch Mountains, in Utah and the Sierra Nevada, that has no natural outlet to the sea. The Great Basin Desert is defined by the extent of characteristic plant species, and covers a somewhat different (and smaller) area. The Great Basin Culture Area, home to several Shoshonean Great Basin tribes, extends further to the north and east than the hydrographic basin. The Basin and Range Province is a geologic region that is most recognizable in the Great Basin but extends well into the Sonoran and Mojave Deserts.

Description

The 200,000 square mile (520,000 square km) intermontane plateau covers most of Nevada and over half of Utah, as well as parts of California, Idaho, Oregon and Wyoming. The Great Basin is not a single basin, but rather a series of contiguous watersheds, bounded on the west by watersheds of the Sacramento-San Joaquin and Klamath rivers, on the north by the watershed of the Columbia-Snake, and on the south and east by the watershed of the Colorado-Green. Watersheds within the Great Basin include:

• Great Salt Lake - Utah, Idaho, Wyoming
• Death Valley - California, Nevada
• Honey Lake - California
• Mono Lake - California
• Humboldt Sink - Nevada (drainage of the Humboldt River, the longest river in the Great Basin)
• Pyramid Lake - Nevada
• Black Rock Desert - Nevada
• Carson Sink - Nevada
• Walker Lake - Nevada
• Winnemucca Lake - Nevada
• Harney Basin - Oregon
• Sevier Lake - Utah
• Abert Lake - Oregon
• Summer Lake - Oregon
• Silver Lake - Oregon
• Surprise Valley - California, Nevada
• Escalante Desert - Utah

Much of the Great Basin, especially across northern Nevada, consists of a series of isolated mountain ranges and intervening valleys, a geographical configuration known as the Basin and Range Province. Additionally the Great Basin contains two large expansive playas that are the lakebed remnants of prehistoric lakes that existed in the basin during the last ice age but have since largely dried up. Lake Bonneville extended over most of Western Utah and into Idaho and Nevada, leaving behind the Great Salt Lake, the Bonneville Salt Flats, Utah Lake, and Sevier Lake. Likewise Lake Lahontan extended across much of northwestern Nevada and neighboring states, leaving behind such remnants as the Black Rock Desert, Carson Sink, Humboldt Sink, Walker Lake, Pyramid Lake, Winnemucca Lake, and Honey Lake, each of which now forms a separate watershed within the basin.

The Basin and Range province's dynamic fault history has profoundly affected the region's water drainage system. Most precipitation in the Great Basin falls in the form of snow that melts in the spring. Rain that reaches the ground, or snow that melts, quickly evaporates in the dry desert environment. Some of the water that does not evaporate sinks into the ground to become ground water. The remaining water flows into streams and collects in short-lived lakes called playas on the valley floor and eventually evaporates. Any water that falls as rain or snow into this region does not escape out of it; not one of the streams that originate within this basin ever finds an outlet to the ocean. The extent of internal drainage, the area in which surface water cannot reach the ocean, defines the geographic region called the Great Basin.

The Great Basin's internal drainage results from blockage of water movement by high fault-created mountains and by lack of sufficient water flow to merge with larger drainages outside of the Great Basin. Much of the present-day Great Basin would drain to the sea - just as it did in the recent Ice Ages - if there were more rain and snowfall.

Geology

The Great Basin is considered by geologists to be in the process of stretching and cracking. Although elevated, the crust here is actually relatively thin, and getting thinner. Some geologists speculate that the East Pacific Rise rift zone may be destined in the distant future to split the Great Basin, possibly by way of the Imperial Valley, letting the sea in from the Gulf of California.

Flora and fauna

The Great Basin is predominantly high altitude desert, with the lowest basins just below 4,000 feet and several peaks over 12,000 feet. Most areas are dominated by shrubs, mostly of the Atriplex genus at the lowest elevations and sagebrush at higher elevations. Open woodlands consisting of Utah Juniper, Single-leaf Pinyon (mostly southern areas) or Curl-leaf Mountain Mahogany (mostly northern areas) form on the slopes of most ranges. Stands of Limber Pine and Great Basin Bristlecone Pine can be found in some of the higher ranges. Cottonwoods and Quaking Aspen groves exist in areas with dependable water.

Lagomorphs such as Black-tailed Jackrabbit and Desert Cottontail and the coyotes that prey on them are the mammals most often encountered by humans. Ground squirrels are common, but they generally venture above ground in only the spring and early summer. Packrats, Kangaroo rats and other small rodents are also common, but these are predominantly nocturnal. Pronghorn, Mule Deer, and Mountain Lion are also present throughout the area. Elk and Bighorn Sheep are present but uncommon.

Small lizards such as the Western fence lizard, Longnose Leopard Lizard and Horned toad are common, especially in lower elevations. Rattlesnakes and Gopher snakes are also present.

Shorebirds such as Phalaropes and Curlews can be found in wet areas. American White Pelicans are common at Pyramid Lake. Golden Eagles are perhaps more common in the Great Basin than anywhere else in the US. Mourning Dove, Western Meadowlark, Black-billed Magpie and Common Raven are other common bird species.

Two endangered species of fish are found in Pyramid Lake that lies in the Great Basin: the Cui-ui sucker fish and the Lahontan cutthroat trout.

Large invertebrates include tarantulas (Aphonopelma genus) and Mormon crickets.

Chukar, Grey Partridge and Himalayan Snowcock have been successfully introduced to the Great Basin, although the latter has only thrived in the Ruby Mountains. Cheatgrass, which was unintentionally introduced, forms a critical portion of their diets. Feral horses (Mustangs) and wild burros are other highly successful, though controversial, alien species. Most of the Great Basin is open range and domestic cattle and sheep are widespread.

History

The history of human habitation in the Great Basin goes back at least 12,000 years. Archaeological evidence of primitive habitation sites along the shore of prehistoric Lake Lahontan date from the end of the ice age when its shoreline was approximately 500 ft (150 m) higher along the sides of the surrounding mountains.

At the time of the arrival of Europeans, the region was inhabited by a broad group of Uto-Aztecan-speaking Native American tribes known collectively as the Great Basin tribes, including the Shoshone, Ute, and Paiute. The first Europeans to encounter the area were the early Spanish explorers in the southwest in the late 18th century. By the early 19th century, fur trappers from the Hudson's Bay Company had explored the upper Basin in the Oregon Country. The first comprehensive and accurate map of the region was made by John C. Frémont during several expeditions across the region in the 1840s.

The United States acquired complete control of the area through the 1846 Oregon Treaty (giving it the small portion north of the 42nd parallel) and the 1848 Treaty of Guadalupe Hidalgo. The first large-scale white settlement in the region was by early Mormon pioneers in the late 1840s in the arable areas around Salt Lake City and the Cache Valley. The Mormons quickly established a provisional government and drafted a proposal for a new state, called the State of Deseret, that encompassed the entire Great Basin, as well as the coast of southern California. The region became successively organized by the creation of the Oregon Territory in 1848, the admission of California to the Union in 1850, and the creation of the Utah Territory in 1850. The discovery of gold in California, in 1848, brought waves of migrants across the Great Basin along the California Trail, which followed the Humboldt River across Nevada. In 1860-61, the Pony Express, came through the area transporting mail from the eastern United States to California.

The part of the first North American transcontinental railroad that was built by the Central Pacific railroad crossed the Great Basin between Reno, Nevada, and Ogden, Utah. Another major railroad southwest from Salt Lake City into Nevada led to the founding of Las Vegas, Nevada.

In 1986, the Great Basin National Park was established by the Federal Government, encompassing 122 square miles of land in Nevada, near the Utah border. The new National Park subsumed the much smaller Lehman Caves National Monument, which had been established in 1922. All of this land is within the Great Basin, and it includes basin and mountainous land, and it is the home of much wildlife.

In the 1950s, the area northeast of Las Vegas was the site of numerous above-ground atomic bomb tests, followed in the 1960s by underground testing.

Present habitation

The Basin has remained among the most sparsely-inhabited areas of the United States. The two largest cities in the basin are Salt Lake City, Utah on its eastern edge and Reno, Nevada on its western edge. Suburbs of Los Angeles, including Lancaster and Palmdale, and Victorville and Hesperia, California combine for about 600,000 residents on the area's southwestern edge. Smaller cities in the basin include Carson City, Nevada; Winnemucca, Nevada; Elko, Nevada; Ogden, Utah; Provo, Utah; and Logan, Utah.

The Great Basin is traversed by major long-distance railroads and expressways, such as the parts of Interstate 80 between Reno and Salt Lake City, Interstate 15 between southwest Utah and Idaho, and Interstate 70 from its junction with Interstate 15 in central Utah from the Great Basin, across the Colorado Plateau to westernmost Colorado. Railroads, such as the Union Pacific, which through merger now owns the routes of the former Southern Pacific and Western Pacific lines, extend from the major metropolitan areas of Denver, Colorado, through Salt Lake City, Utah, and Reno, Nevada, to the San Francisco, California, Bay Area; and from Salt Lake City to Los Angeles, California.

See also

• Great Basin National Park
• Lake Bonneville
• List of deserts by area
• List of rivers in the Great Basin
• Wasatch Range
• Basin and Range Province

References

• USGS: Geologic Provinces of the United States: Basin and Range Province
• Basin and Range, John McPhee (1980)
• The Sagebrush Ocean: A Natural History of the Great Basin, Stephen Trimble (1999) ISBN - 0874173434
• USGS: North America Basins Map

External links

• Great Basin project of the American Land Conservancy
• Map of Great Basin from Great Basin Web
• Great Basin--Mojave Desert Region
• Exploring the Great Basin
• Great Basin Shrub Steppe images at bioimages.vanderbilt.edu (slow modem version)
• Great Basin Montane Forests images at bioimages.vanderbilt.edu (slow modem version)

Deserts

Ad-Dahna · Alvord · Arabian · Aral Karakum · Atacama · Baja California · Barsuki · Betpak-Dala · Chalbi · Chihuahuan · Dasht-e Kavir · Dasht-e Lut · Dasht-e Margoh · Dasht-e Naomid · Gibson · Gobi · Great Basin · Great Sandy Desert · Great Victoria Desert · Kalahari · Karakum · Kyzylkum · Libyan · Little Sandy Desert · Mojave · Monte · Namib · Nefud · Negev · Nubian · Ordos · Owyhee · Patagonian · Qaidam · Registan · Rub' al Khali · Ryn-Peski · Sahara · Saryesik-Atyrau · Sechura · Simpson · Sonoran · Strzelecki · Syrian · Taklamakan · Tanami · Thar · Tihamah · Ustyurt

Geographic regions of the United States
Northeast	New England - Mid-Atlantic • East Coast - Atlantic Northeast
Midwest	E North Central - W North Central • Upper Midwest • Great Lakes - Great Plains
South	Upland South - Deep South - Gulf Coast • South Atlantic - Southeast - South Central
West	Pacific/West Coast - Mountain • Northwest - Southwest • Pacific NW - Great Basin
Other	North - East - Central • Coastal - International Border - North Coast

	State of California Sacramento (capital)
Topics	Climate | Culture | Districts | Economy | Elections | Geography | Government | Early History | Modern History | Politics | Californians
Regions	Antelope Valley | Big Sur | Cascade Range | Central Coast | Central Valley | Channel Islands | Coachella Valley | Conejo Valley | Cucamonga Valley | Death Valley | East Bay (SF) | Eastern California | Emerald Triangle | Gold Country | Great Basin | Greater Los Angeles | Inland Empire | Lake Tahoe | Los Angeles Basin | Mojave | North Bay (SF) | North Coast | Northern California | Owens Valley | The Peninsula | Pomona Valley | Redwood Empire | Russian River | Sacramento Valley | San Fernando Valley | San Francisco Bay Area | San Joaquin Valley | Santa Clara Valley | Santa Clarita Valley | Shasta Cascade | Sierra Nevada | Silicon Valley | South Bay (SF) | Southern California | Tech Coast | Tri‑Valley | Wine Country | Yosemite
Metro areas	Bakersfield | Chico | El Centro | Fresno | Los Angeles–Long Beach–Glendale | Madera | Modesto | Merced | Napa | Oakland–Fremont–Hayward | Oxnard–Thousand Oaks–Ventura | Redding | Riverside–San Bernardino–Ontario | Sacramento–Roseville | Salinas | San Diego–Carlsbad–San Marcos | San Francisco–San Mateo–Redwood City | San Jose–Sunnyvale–Santa Clara | Santa Ana–Anaheim–Irvine | Santa Barbara–Santa Maria | Santa Cruz–Watsonville | Santa Rosa–Petaluma | Stockton | Vallejo–Fairfield | Visalia–Porterville | Yuba City
Counties	Alameda | Alpine | Amador | Butte | Calaveras | Colusa | Contra Costa | Del Norte | El Dorado | Fresno | Glenn | Humboldt | Imperial | Inyo | Kern | Kings | Lake | Lassen | Los Angeles | Madera | Marin | Mariposa | Mendocino | Merced | Modoc | Mono | Monterey | Napa | Nevada | Orange | Placer | Plumas | Riverside | Sacramento | San Benito | San Bernardino | San Diego | San Francisco | San Joaquin | San Luis Obispo | San Mateo | Santa Barbara | Santa Clara | Santa Cruz | Shasta | Sierra | Siskiyou | Solano | Sonoma | Stanislaus | Sutter | Tehama | Trinity | Tulare | Tuolumne | Ventura | Yolo | Yuba

	State of Idaho Boise (capital)
Topics	Culture | Geography | Government | Governors | History | Images
Regions	Boise metropolitan area | Cache Valley | Central Idaho | Columbia River Plateau | Eastern Idaho | Great Basin | Idaho Panhandle | Inland Empire | Magic Valley | North Central Idaho | North Idaho | Palouse | Southern Idaho | Southwestern Idaho | Treasure Valley | Wasatch Range | Wood River Valley | Yellowstone
Larger cities	Boise | Coeur d'Alene | Idaho Falls | Lewiston | Meridian | Nampa | Pocatello | Twin Falls
Smaller cities	Ammon | Blackfoot | Burley | Caldwell | Chubbuck | Eagle | Garden City | Kuna | Moscow | Mountain Home | Post Falls | Rexburg
Counties	Ada | Adams | Bannock | Bear Lake | Benewah | Bingham | Blaine | Boise | Bonner | Bonneville | Boundary | Butte | Camas | Canyon | Caribou | Cassia | Clark | Clearwater | Custer | Elmore | Franklin | Fremont | Gem | Gooding | Idaho | Jefferson | Jerome | Kootenai | Latah | Lemhi | Lewis | Lincoln | Madison |