The Grand Canyon is a colorful steep-sided gorge carved by the Colorado River in the U.S. state of Arizona. 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 preservation of the Grand Canyon area, and visited on numerous occasions to hunt and enjoy the scenery.

The canyon, created by the Colorado River over a period of 6 million years, is 277 miles (446 km) long, ranges in width from 4 to 18 miles (6.4 to 29 km) and attains a depth of more than a mile (1.6 km). Nearly two billion years of the Earth's history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted.

During prehistory, the area was inhabited by Native Americans who built settlements within the canyon and its many caves. The Pueblo people considered the Grand Canyon ("Ongtupqa" in Hopi language) a holy site and made pilgrimages to it.

The first European known to have viewed the Grand Canyon was Garcia Lopez de Cardenas from Spain, who arrived in 1540.

The Grand Canyon was largely unexplored until after the U.S. Civil War. In 1869, Major John Wesley Powell, a one-armed Civil War veteran with a thirst for science and adventure, made the first recorded journey through the canyon on the Colorado River. He accomplished this trek with nine men in four small wooden boats, though only six men completed the journey. Powell referred to the sedimentary rock units exposed in the canyon as "leaves in a great story book".

Most visitors to the park come to the South Rim, arriving on Arizona Highway 64. The Highway enters the park through the South Entrance, near Tusayan, Arizona, and heads eastward, leaving the park through the East Entrance. All park accommodations are operated by the Xanterra corporation. Park headquarters are at Grand Canyon Village, a short distance from the South Entrance, being also the center of the most popular viewpoints. Some thirty miles of the South Rim are accessible by road. A much smaller venue for tourists is found on the North Rim, accessed by Arizona Highway 67. There is no connection by road between the two, except via the Navajo Bridge, entailing a five-hour drive. The rest of the Grand Canyon is extremely rugged and remote, although many places are accessible by pack trail and backcountry roads.

The area around the Grand Canyon became a national monument on January 11, 1908 and was designated national park on February 26, 1919. The creation of the park was an early success of the environmental conservation movement; its National Park status may have helped thwart proposals to dam the Colorado River within its boundaries. (Lack of this fame may have enabled Glen Canyon Dam to be built upriver, flooding Glen Canyon and creating Lake Powell.) UNESCO has declared it as a World Heritage Site.

The Grand Canyon itself, including its extensive system of tributary canyons, is valued for the spectacular combination of large size, depth, and the exposed layering of colorful rocks dating back to Precambrian times. It was created through the incision of the Colorado River and its tributaries after the Colorado Plateau was uplifted and the Colorado River system developed along its present path.

additional information from Wikipedia

12/18/07 by visitEarth
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