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| |- | |- | |- | |} For other Grand Canyons see Grand Canyon (disambiguation) . The Grand Canyon is a very colorful, steep-sided Gorge , carved by the Colorado River , in northern Arizona , USA . The Canyon appears on many versions of the Seven Natural Wonders Of The World list, although none of these lists are by any means authoritative. It is largely contained within the Grand Canyon National Park — one of the first national parks in the United States. President Theodore Roosevelt was a major proponent of the Grand Canyon area, visiting on numerous occasions to hunt Mountain Lion s and enjoy the scenery. The canyon, created by the Colorado River cutting a Channel over millions of years, is about 277 miles (446 km) long, ranges in width from 0.25 to 18 miles (0.5 to 29 kilometers) and attains a depth of more than a mile (1,600 m). Nearly two billion years of the Earth 's history has been exposed as the Colorado River and its tributaries cut through layer after layer of Sediment as the Colorado Plateau s have uplifted. The first recorded sighting of the Grand Canyon by a Europe an was in 1540, García López De Cárdenas from Spain . The first scientific expedition to the canyon was led by U.S. Major John Wesley Powell in the late 1870s. Powell referred to the Sedimentary Rock units exposed in the canyon as "leaves in a great story book." However, long before that, the area was inhabited by Native American s who built settlements within the canyon walls. Geography The Grand Canyon is a very deep - in places over a mile deep - 277 mile (446 km) long cut in the Colorado Plateaus that exposes uplifted Proterozoic and Paleozoic strata. The exposed strata are gradually revealed by the gentle incline beginning at Lee's Ferry and continuing to Hance Rapid. At the point where the river crosses the Grand Wash Fault (near Lake Mead ) the Canyon ends. Uplift associated with Plate Tectonics -caused Mountain building events later moved these sediments thousands of feet upward and created the Colorado Plateaus. The higher Elevation has also resulted in greater Precipitation in the Colorado River drainage area, but not enough to change the Grand Canyon area from being semi-arid. Landslide s and other Mass Wasting events then caused Headward Erosion and Stream Capture - all of which tend to increase the depth and width of canyons in arid environments. The uplift of the Colorado Plateaus is uneven, resulting in the North rim of the Grand Canyon being over a thousand feet (about 300 meters) higher than the South rim. The fact that the Colorado River flows closer to the South rim is also explained by this asymmetrical uplift. Almost all runoff from the Plateau behind the North rim (which also gets more Rain and Snow ) flows toward the Grand Canyon, while much of the runoff on the plateau behind the South rim flows away from the canyon (following the general tilt). The result is much greater Erosion and thus faster widening of the canyon and its tributary canyons north of the Colorado River . Temperatures on the North rim are generally lower than the South rim because of the greater elevation (8000 feet/2438 meters above sea level). Heavy Snowfall is common during the Winter months. Views from the North rim tend to give a better impression of the expanse of the canyon rather than the views down which characterize the South Rim. Geology Main article: Geology Of The Grand Canyon Area The details of the canyon's formation are still highly controversial. Geologists continue to debate ideas about the formation of Grand Canyon. According to Geologist Wayne Ranney: "To date, geologists have been unable to determine the canyon's precise age and what specific processes were at work in carving it". There is no authoritative theory on the formation of Grand Canyon. The major geologic exposures in Grand Canyon range in age from the 2000 million year old Vishnu Schist at the bottom of the Inner Gorge to the 230 million year old Kaibab Limestone on the Rim. Many of the Formations were deposited in warm shallow seas, near-shore environments (such as Beach es), and Swamp s as the seashore repeatedly advanced and retreated over the edge of a proto- North America . Major exceptions include the Cococino Sandstone which was laid down as Sand Dune s in a Desert and several parts of the Supai formation. The great depth of the Grand Canyon and especially the height of its strata (most of which formed below Sea Level ) can be attributed to 5000 to 10,000 feet (1500 to 3000 m) of uplift of the Colorado Plateaus starting about 65 million years ago (during the Laramide Orogeny ). This uplift has steepened the Stream Gradient of the Colorado River and its tributaries, which in turn has increased their speed and thus their ability to cut through rock (see the Elevation Summary of the Colorado River for present conditions). The Colorado River basin (of which the Grand Canyon is a part) has developed in the past 40 million years and the Grand Canyon itself is probably less than five to six million years old (with most of the Downcutting occurring in the last two million years). The result of all this Erosion is one of the most complete geologic columns on the planet. Wetter conditions during Ice Age s also increased the amount of water in the Colorado River drainage system. The ancestral Colorado River responded by cutting its channel faster and deeper. Then the base level and course of the Colorado River (or its ancestral equivalent) changed 5.3 million years ago when the Gulf Of California opened and lowered the river's Base Level (its lowest point). This increased the rate of erosion and cut nearly all of the Grand Canyon's current depth by 1.2 million years ago. The terraced walls of the canyon were created by Differential Erosion . A million years ago Volcanic activity (mostly near the western canyon area) deposited Ash and Lava over the area which at times completely obstructed the river. These volcanic rocks are the youngest in the canyon. Human history ''Main article: History Of The Grand Canyon Area '' The Ancestral Puebloans (The Ancient Ones, or Anasazi)
The Modern Hopi (see also Pueblo People ) Other cultures
European discovery and settlement The Spanish Explorers In September 1540, under orders from the Conquistador Francisco Vasquez De Coronado to search for the fabled Seven Cities Of Cibola , Captain Garcia Lopez De Cardenas , along with Hopi guides and a small group of Spanish soldiers, traveled to the South Rim of the Grand Canyon between Desert View and Moran Point. Pablo De Melgrossa , Juan Galeras and a third soldier descended some one third of the way into the Canyon until they were forced to return because of lack of water. It is speculated that their Hopi guides must have been reluctant to lead them to the river, since they must have known routes to the canyon floor. No Europeans visited the canyon for over 200 years.
American Exploration James Ohio Pattie , with a group of American trappers and mountain men were probably the next Europeans to reach the Canyon in 1826, although there is little documentation to support this. Jacob Hamblin (a Mormon missionary) was sent by Brigham Young in the 1850's to locate easy river crossing sites in the Canyon. Building good relations with local Native Americans and white settlers, he discovered Lee's Ferry in 1858 and Pierce Ferry (later operated by, and named for, Harrison Pierce ) - the only two sites suitable for ferry operation. In 1857, the U.S. War Department asked Lieutenant Joseph Ives to lead an expedition to assess the feasibility of an up-river navigation from the Gulf of California. Also in a stern wheeler steamboat "Explorer", after two months and 350 miles of difficult navigation, his party reached Black Canyon some two months after George Johnson. The "Explorer" struck a rock and was abandoned. Ives led his party east into the Canyon - they were the first Europeans to travel the Diamond Creek drainage and traveled eastwards along the South Rim. James White (this links to a disambiguation page that does not contain a link to this James White yet!)
Settlement on the rim
Many challenges face the federal government administrators who manage park resources. These include issues related to: the recent reintroduction into the wild of the highly endangered California Condor, air tour overflight noise levels, water rights disputes with various tribal reservations that border the park, and forest fire management. The Grand Canyon National Park superintendent is Mr. Joe Alston who was previously the superintendent of Glen Canyon National Recreation Area (Lake Powell. Glen Canyon lies to the North and East of Grand Canyon on the Arizona/Utah Border. Recent history In 1956 the Grand Canyon was the site of America's worst commercial aviation disaster at the time. On the morning of June 30 , 1956, a TWA Lockheed Super Constellation and a United Airlines Douglas DC-7 departed Los Angeles International Airport within three minutes of one another on eastbound transcontinental flights. Approximately 90 minutes later, the two propeller-driven airliners collided above the canyon while both were flying in unmonitored airspace. The wreckage of both planes fell into the eastern portion of the canyon, on Temple and Chuar buttes, near the confluence of the Colorado and Little Colorado rivers. The disaster killed all 128 passengers and crew members aboard both planes. Activities Aside from casual sightseeing from the South Rim (averaging 7000 feet/2134 m above sea level), Whitewater Rafting and hiking are especially popular. The floor of the valley is accessible by hiking, muleback, or by boat or raft from upriver. Hiking down to the river and back up to the rim in one day is highly discouraged by park officials, due to the distance, effort required, and danger of Heat Exhaustion from the much higher temperatures at the bottom. Even hiking along the rim must be done with care in spots, and there are frequent warning signs posted along rim trails. The National Park Service provides wheelchairs for temporary day use by park visitors. No rental fee is charged. Image:Grand Canyon 29 Aug 2001 22-08.jpg|The Grand Canyon from inside Image:Satellite image of the Grand Canyon.jpeg|The Grand Canyon as seen from Earth orbit. Image:Grand_Canyon.jpg.jpg|Two hikers looking down on the Grand Canyon Image:Grand_Canyon_from_Moran_Point.jpeg|Grand Canyon from Moran Point image:GrandNP4.jpg|Grand Canyon backcountry image:GrandNP3.jpg|Grand Canyon backcountry image:GrandNP2.jpg|Grand Canyon backcountry image:GrandNP.jpg|Grand Canyon from Tiyo Point Image:USA_grand_canyon_pano1_AZ.jpg|Sunrise at the Grand Canyon Image:Grandcanyon view5.jpg|The Grand Canyon Image:GrandGranyon-sunset.jpg|Sunset seen from South rim Image:Stamp-ctc-grand-canyon-national-park.jpg|The United States government made the Grand Canyon a national park in 1919 See also References
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