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The Black Rock Desert is a semi-arid region ''(in the Great Basin shrub steppe eco-region)'', of lava beds and playa, or alkali flats, situated in the Black Rock Desert-High Rock Canyon Emigrant Trails National Conservation Area, a silt playa north of Reno that encompasses more than of land and contains more than of historic trails. It is in the northern Nevada section of the Great Basin with a lakebed that is a dry remnant of Pleistocene Lake Lahontan. The average annual precipitation ''(years 1971-2000)'' at Gerlach (extreme south-west of the desert) is . The Great Basin, named for the geography in which water is unable to flow out and remains in the basin, is a rugged land serrated by hundreds of mountain ranges, dried by wind and sun, with spectacular skies and scenic landscapes.〔http://blackrockdesert.org/friends/general-information〕 The region is notable for its paleogeologic features, as an area of 19th-century Emigrant Trails to California, as a venue for rocketry, and as an alternative to the Bonneville Salt Flats in northwestern Utah, for setting land speed records (Mach 1.02 in 1997). It is also the location for the annual Burning Man festival. The Black Rock Desert is part of the National Conservation Area (NCA), a unit of the Bureau of Land Management (BLM) National Landscape Conservation System (NLCS). The NCA is located in northwest Nevada, and was established by legislation in 2000. It is a unique combination of desert playa, narrow canyons, and mountainous areas. Humans have been in Black Rock Desert since approximately 11,000 BC. In 1300 BC the area was settled by the Paiute people. The large black rock formation was used as a landmark by the Paiute and later emigrants crossing the area. The landmark is a conical outcrop composed of interbedded Permian marine limestone and volcanic rocks. At its base is a large hot spring and grassy meadow, which was an important place for those crossing the desert headed for California and Oregon. In 1843, John Fremont and his party were the first white men to cross the desert, and his trail was used by over half the 22,000 gold seekers headed to California after 1849. In 1867, Hardin City, a short-lived silver mill town was established (now a ghost town). ==Geography== The Black Rock Desert region is in northwestern Nevada and the northwestern Great Basin. The playa extends for approximately northeast from the towns of Gerlach and Empire, between the Jackson Mountains to the east and the Calico Hills to the west. The Black Rock Desert is separated into two arms by the Black Rock Range. It lies at an elevation of 〔 and has an area of about .〔 There are several possible definitions of the extent of the Black Rock Desert. Often people refer just to the playa surface. Sometimes terrain which can be seen from the playa is included. The widest definition of the Black Rock Desert region is the watershed of the basin that drains into the playa. The intermittent Quinn River is the largest river in the region, starting in the Santa Rosa Range and ending in the Quinn River Sink on the playa south of the Black Rock Range. The watershed covers including the Upper and Lower Quinn River, Smoke Creek Desert, Massacre Lake, and Thousand Creek/Virgin Valley watersheds of northwestern Nevada as well as small parts across the borders of California and Oregon. If the playa is wet for a month or so, the shallow waters teem with fairy shrimp, or anostraca born of eggs that lay dormant in the silt crust for long periods of time - sometimes for many years. The edges of the playa and the Quinn River Sink stay wet longer than the rest of the playa, which concentrates the fairy shrimp and migratory birds in those areas. More than 250 species of neo-tropical birds and many other water birds stop in Black Rock-High Rock Country for varying lengths of time. When wet, especially in spring, the playa is a favorite place for these winged visitors to rest and feed.〔 When it rains, the playa can become extremely sticky, bogging down four-wheel-drive vehicles. Some areas of the Black Rock are environmentally sensitive and closed to all vehicles. Humboldt, Pershing and Washoe Counties of Nevada intersect at the Black Rock Desert. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Black Rock Desert」の詳細全文を読む スポンサード リンク
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