Grand Canyon National Park
| Grand Canyon National Park Grand Canyon National Park (en) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 The Grand Canyon. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| IUCN category | II ( National Park ) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Id | 992 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Country |  United States | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| State |  Arizona | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Counties | Coconino and Mohave | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Nearest city | Flagstaff | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Contact | 36 12 '00 "North 113 14 '00 "West / 36.200000, -113.233333 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Area | 4 927 km 2 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Creation | 26 February 1919 in 2008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Administration | National Park Service | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Website | Grand Canyon National Park | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Note | Ranked 11 in January 1908 as a National Monument . It is visited annually by more than four million visitors. The natural diversity and landscape of the region was recognized World Heritage of Humanity by UNESCO in 1979.
GeographyLocation and dimensions  Grand Canyon Park is located in the southwest United States, north of the State of Arizona. The dimensions of the Grand Canyon are huge: it covers about 450 km long between Lake Powell and Lake Mead. Its average depth is 1300 meters with a maximum of over 2000 meters . Its width varies from 5.5 km to 30 km , . The Grand Canyon is neither the deepest nor the most impressive canyons land: the Canyon of Yarlung Zangbo in China , the Barranca del Cobre, located in northern Mexico and the Hells Canyon in the Idaho are deeper grooves. But the site is notable for the views offered to visitors and geological layers that appear on the cliffs , well known to geologists. The layers tell the story of the North American continent. On the other hand, the place is the spectacular result of the work of erosion , particularly that of the Colorado River which flows down-cons. Climate
Hydrography Main article: Colorado (river). The Grand Canyon was carved by the force of Colorado has its source in the Rocky Mountains and empties into the Gulf of California after having driven about 2 333 km , . Down from Yavapai Point, the river is 750 meters above sea level . The flow through the river is 650 m / s , however, during periods of flood , it may increase significantly: before the construction of dams, the flow could reach 2300 m / s . One hundred rapids are at the bottom of the canyon . Several tributaries flow into the Colorado Kanab Creek, Havasu Creek, Little Colorado and Paria River. Many rivers are temporary and depend on rainfall and the season. GeologyThe Grand Canyon has rocks which are among the oldest of the Earth: some are aged 1, 7 billion years at the bottom of the grooves . An estimated one thousand the number of caves and caverns in the Grand Canyon: only 335 have been recognized . Most of them are found in geological formations of Redwall and MUAV . Some are highly frequented by tourists, like the Domes at Horseshoe Mesa, which are attracted by the speleothems ( stalactites , stalagmites , etc..). Geological historyIt is possible to go back to around 1.7 billion years to describe the history of the Grand Canyon . In the late Precambrian (era Proterozoic ), the sedimentary rocks that had slowly formed here were metamorphosed under the action of high pressures and high temperatures of magma. There are about 1.2 billion years , in the late Proterozoic, 4,000 meters of sediment and lava accumulated in a shallow sea. About 725 million years , these rocks were deformed and raised to become a mountain. A long process of erosion followed this period. Then the area was again invaded by the sea several times between 550 and 250 million years, resulting in the formation of new layers of sandstone, limestone and shale (groups of Supai and Tonto). Between 80 and 35 million years ago, the Laramide orogeny leads to the formation of the Rocky Mountains, located further west and deformations in the region of the current Grand Canyon. Intense volcanic activity began there are 6 million years , causing large flows of lava. An initial hypothesis was that the Grand Canyon itself was formed from the late Cenozoic by the erosive action of Colorado, reinforced by the opening of the Gulf of California downstream. New eruptions have produced lava flows that formed several plugs into the groove and formed lakes with a depth of up to 600 meters. According to the most recent mineralogical data, it could be older than 17 million years, or 11 million years older than previously thought (early 2008 estimate by the California Institute of Technology). Then the University of Colorado found that there existed 55 million years and that he could begin to dig there are 65 million years, at the end of the age of dinosaurs . Geological formations today Nearly 40 different rock layers were identified on the walls of the Grand Canyon . The main formations of the Grand Canyon are:
The Colorado Plateau based on a base formed during the Precambrian , there are between 1.6 and 1.8 billion years . The rocks of this basement outcropping in various places in the canyon: the Vishnu schists are the oldest, dating from the Proterozoic. They are very old deposits (ash, sludge, sand) transformed into sedimentary rocks and metamorphosed. The Coconino Sandstone and Redwall are fairly resistant to erosion . The Bright Angel Shale and Hermit are softer . Earthquake, volcanism and faulting45 earthquakes have affected the Grand Canyon or the region during the twentieth century: five have reached magnitudes between 5 and 6 on the Richter scale . Today, there are more active volcano in the Grand Canyon area. The last lavas date from about 10,000 years . The last eruption of Sunset Crater , located south of the Grand Canyon took place around 1100. The presence of numerous faults reflect tectonic activity which has affected and still affects the region of the Grand Canyon. Bright Angel Fault Fault runs through the canyon between Grand Canyon Village to the north shore. Natural EnvironmentThe Grand Canyon National Park has a wide diversity of ecosystems : their characteristics depend on many factors: location, sun exposure, type of soil , altitude , etc.. The fauna and flora are more or less subject to the action of man and the tourist pressure. Fauna355 species of birds , 89 mammals , 47 reptiles , 9 of amphibians , 17 fish , and thousands of species of invertebrates were recorded in the park of the Grand Canyon . The puma , the lynx , the coyote and the Rocky Mountain goat are mammals that live on both sides, but they are difficult to observe.  Several species are threatened or endangered : Oxyloma haydeni kanabensis is a snail that is found in some meadows of the park. The Gila Chalice and Xyrauchen texanus are two fish that live in Colorado and its tributaries. Pelecanus occidentalis californicus or the California brown pelican and the Empidonax traillii are also very rare. The California condor , one of the largest birds on earth, has been reintroduced in the 1990s. This past 40,000 years in the Grand Canyon, it has almost disappeared because of hunting and poisoning. In 1987, there were only thirty people in the world, with only nine free ( California ) . Today they are 305, including sixty Arizona . Missing the region in the 1920s, they were ranked on the list of endangered species in 1967 and three pairs were reintroduced in 1996. They are all numbered and fitted with a radio transmitter . The California Condors lay only one egg a year or every two years. They reach sexual maturity until age 5 or 6 years , we find this scavenger mainly east of the park where he took advantage of upslope winds to move. Past EcosystemsThe Grand Canyon retains many fossils, the oldest of which date back to Precambrian (traces of algae and spores ) . The paleontologists have found in the caves of the Grand Canyon of hair, bones and animal droppings have disappeared . These accounts of wildlife that lived during the last glaciation are well preserved thanks to the aridity of the region. Specialists have discovered the bones of the California condor back several thousand years and perfectly preserved by drying. Droppings mammoths have enabled scientists to reconstruct the environment at the time of Wisconsin. With rising temperatures, the megafauna of the Pleistocene eventually disappear from the region, mastodon , giant sloths , camels , horses , saber-toothed tiger . Interior of the grooves and ridges of ColoradoThe walls facing north receive less sun than others: they are colonized by plants that are usually found at higher altitudes or farther north. The south-facing walls have a typical vegetation of the Sonoran Desert . A hundred pairs of peregrine falcons (Falco peregrinus anatum) live in the park , . They feed on bats and small birds. One can also observe prairie falcons (Falco mexicanus). Eagles fishing on the banks of the Colorado River and its tributaries. There are also various water birds (ducks ...). Hyla, Bufo punctatus and Bufo arenicolor woodhousii woodhousii amphibians are the most common . North ShoreThe north shore is wetter and cooler than the south shore. Elevations reach 2,800 meters . There are forests of conifers : ponderosa pine , blue spruce
South Shore The south shore is more arid than the north shore. The vegetation is adapted to water shortages and altitude: cactus , Utah juniper , pinyon pine .
To the westWhen the Colorado form Lake Mead elevation is 365 feet . The West Park is part of the Mojave Desert with bushes ( Atriplex canescens , Larrea tridentata ), shrubs and plants adapted to drought ( Utah Agave , Rhatany , Acacia greggii , cactus ) . Flora
Between 1300 and 1900 meters there are forests of pinyon and juniper of Utah (Juniperus osteosperma) , . Other species such as the Artemisia tridentata , the ephedra , the Yucca baccata , the Oryzopsis hymenoides the Sporobolus grow also on this floor .
Current ThreatsSince the nineteenth century, humans change the environment of the Grand Canyon. Deforestation and fires set back the forests of the north and threaten wildlife . HistoryPre-Columbian PeriodThe Colorado Plateau and, in general, the southwest United States today, was occupied by the Anasazi : they have left numerous traces in the region and petroglyphs. Discovery and ExplorationThe conquistadors Spanish were the first white men to reach the region. In 1540, the viceroy of Spain sends an expedition from Mexico to the north today, to find the golden cities of Cibola. Captain Don a href = "% C3% Garc ADa_L% C3% B3pez_de_C% C3% A1rdenas"> Garca Lpez de Crdenas discovered the Grand Canyon then although no cross after failing to find a passage between the two sides. Missionaries are subsequently sent to evangelize the indigenous people. The region remains unknown until the mid-nineteenth century. But the conquest of the West and population growth are pushing Americans to map the area. In 1869, John Wesley Powell , a veteran of the Civil War , down the Colorado River by boat: his expedition cost the lives of three of the nine men . The story of Powell arouses the interest of geologists and nature lovers. Facilities and DevelopmentIn the early twentieth century, the region grows and the Grand Canyon is increasingly popular, especially by hunters. The railway reached the south bank in 1901 . The first hotel was opened shortly after . Given the human pressure, the government decided to classify the area in national park in 1919. But the Colorado River is tamed by the creation of Hoover Dam downstream in the 1930s and the Glen Canyon Dam upstream in 1950-1960 (216 meters high, 475 meters wide at the crest ). Tourism The grounds of the Grand Canyon is one of the most visited sites in the United States. Its usage is increasing: the number of tourists rose from 3.9 million in 2002 to 4.5 million in 2007. HikingThe peculiarity of hiking in a canyon is that it starts to descend ... and that the return is going up, as opposed to hiking in the mountains. This characteristic makes the hike in the Grand Canyon can be dangerous and is very easy to get and much harder to trace. However some hikers never stop going down until they begin to be tired or hungry. So many signs "Danger of death" are displayed at the beginning of the descent to inform tourists of the dangers and to sensitize them to be very careful. The two main tourist access the North Rim (inaccessible from November to April because of snow) and the South Rim. A hiking trail connects these two access across the river Colorado from Grand Canyon Village. The park authorities strongly advise against going down to the river and up the canyon on a single day, especially as the temperature can reach 40 degrees Celsius in summer. GatewayA glass bridge called the Grand Canyon Skywalk "was inaugurated March 20, 2007 at Grand Canyon West . It allows visitors to find 1300 meters above the vacuum. It was partly funded by David Jin, a businessman from Las Vegas. The book does not connect the two sides of the canyon but forms a small loop that extends from 22 meters vertically Colorado . The platform weighs 500 tons. It is capable of supporting the weight of hundreds of people while being exposed to the winds. The project has been decided by the Hualapai Tribe for economic reasons. Admission is 33 (about 22 ) . But some complain that the landscape is altered, all that work should continue to develop luxury restaurant, a museum, a cinema and meeting space near the Skywalk . Photographs
 NotesBibliography
Internal linkExternal Links
Notes
References
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Loading ...