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Death Valley National Park is a national park in the U.S. states of California and Nevada that is located east of the Sierra Nevada, occupying an interface zone between the arid Great Basin and Mojave deserts in the United States. The park protects the northwest corner of the Mojave Desert and contains a diverse desert environment of salt-flats, sand dunes, badlands, valleys, canyons, and mountains. It is the largest national park in the lower 48 states and has been declared an International Biosphere Reserve. Approximately 95% of the park is a designated wilderness area.〔NPS website, "Backcountry Roads"〕 It is the hottest and driest of the national parks in the United States. The second-lowest point in the Western Hemisphere is in Badwater Basin, which is below sea level. The park is home to many species of plants and animals that have adapted to this harsh desert environment. Some examples include creosote bush, bighorn sheep, coyote, and the Death Valley pupfish, a survivor of much wetter times. A series of Native American groups inhabited the area from as early as 7000 BC, most recently the Timbisha around 1000 AD who migrated between winter camps in the valleys and summer grounds in the mountains. A group of European-Americans that became stuck in the valley in 1849 while looking for a shortcut to the gold fields of California gave the valley its name, even though only one of their group died there. Several short-lived boom towns sprang up during the late 19th and early 20th centuries to mine gold and silver. The only long-term profitable ore to be mined was borax, which was transported out of the valley with twenty-mule teams. The valley later became the subject of books, radio programs, television series, and movies. Tourism blossomed in the 1920s, when resorts were built around Stovepipe Wells and Furnace Creek. Death Valley National Monument was declared in 1933 and the park was substantially expanded and became a national park in 1994.〔National Park Index (2001–2003), p. 26〕 The natural environment of the area has been shaped largely by its geology. The valley itself is actually a graben. The oldest rocks are extensively metamorphosed and at least 1.7 billion years old.〔 Ancient, warm, shallow seas deposited marine sediments until rifting opened the Pacific Ocean. Additional sedimentation occurred until a subduction zone formed off the coast. This uplifted the region out of the sea and created a line of volcanoes. Later the crust started to pull apart, creating the current Basin and Range landform. Valleys filled with sediment and, during the wet times of glacial periods, with lakes, such as Lake Manly. In 2013, Death Valley National Park was designated as a dark sky park by the International Dark-Sky Association. ==Geographic setting== There are two major valleys in the park, Death Valley and Panamint Valley. Both of these valleys were formed within the last few million years and both are bounded by north–south-trending mountain ranges.〔 These and adjacent valleys follow the general trend of Basin and Range topography with one modification: there are parallel strike-slip faults that perpendicularly bound the central extent of Death Valley. The result of this shearing action is additional extension in the central part of Death Valley which causes a slight widening and more subsidence there. Uplift of surrounding mountain ranges and subsidence of the valley floor are both occurring. The uplift on the Black Mountains is so fast that the alluvial fans (fan-shaped deposits at the mouth of canyons) there are small and steep compared to the huge alluvial fans coming off the Panamint Range. Fast uplift of a mountain range in an arid environment often does not allow its canyons enough time to cut a classic V-shape all the way down to the stream bed. Instead, a V-shape ends at a slot canyon halfway down, forming a 'wine glass canyon.' Sediment is deposited on a small and steep alluvial fan. At below sea level, Badwater Basin on Death Valley's floor is the second-lowest depression in the Western Hemisphere (behind Laguna del Carbón in Argentina), while Mount Whitney, only to the west, rises to . This topographic relief is the greatest elevation gradient in the contiguous United States and is the terminus point of the Great Basin's southwestern drainage.〔 Although the extreme lack of water in the Great Basin makes this distinction of little current practical use, it does mean that in wetter times the lake that once filled Death Valley (Lake Manly) was the last stop for water flowing in the region, meaning the water there was saturated in dissolved materials. Thus the salt pans in Death Valley are among the largest in the world and are rich in minerals, such as borax and various salts and hydrates. The largest salt pan in the park extends from the Ashford Mill Site to the Salt Creek Hills, covering some of the valley floor.〔〔Badwater, the Devils Golf Course, and Salt Creek are all part of the Death Valley Saltpan.〕 The best known playa in the park is the Racetrack, known for its moving rocks. Death Valley NP master map.png|Map of the park showing old Monument land (light green) and the expanded Park land (dark green) 2006 1205 135618-DVNP-RACETRACK.jpg|Racetrack Playa, view from south edge of the playa towards The Grandstand BadwaterSL.JPG|Sea Level sign seen on cliff (circled in red) at Badwater Basin, Death Valley National Park. BadwaterBasin.JPG|Badwater Basin elevation sign and scenery. Death Valley,19820817,Desert,radiator water tank.jpg|Desert and abandoned radiator water tank near Grapevine 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「Death Valley National Park」の詳細全文を読む スポンサード リンク
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