great gorge of the Colorado River, one of the natural wonders of the world; c.1 mi (1.6 km) deep, from 4 to 18 mi (6.4–29 km) wide, and 217 mi (349 km) long, NW Ariz. The canyon shows in its rocks the repeated geological sequence of uplift, erosion (due to the river's constant wearing force), submergence, and deposition of materials. The multicolored rocks, the steep and embayed rims, and the isolated towers, mesas, "temples," and other eroded rock forms catch the contrast of sun and shadow and glow with changing hues of great beauty. Plant life on the canyon walls varies from subtropical at the base to subarctic near the rims. Hundreds of ancient pueblos dot the lower canyon walls and the rim, and the Havasupai people still occupy a part of the canyon. The first European to see the canyon was the Spanish explorer García López de Cárdenas in 1540. In 1869 the U.S. explorer John Wesley Powell became the first person to lead a party through the canyon bottom in a boat.

The Grand Canyon was set aside by the U.S. government in 1908 as a national monument. In 1919 an expanded area was designated Grand Canyon National Park (1,217,403 acres/492,876 hectares). The park was enlarged in 1975 to include other areas, such as Marble Canyon and parts of Glen Canyon and Lake Mead. Along the forested northern rim and the more accessible southern rim are numerous lookouts, and trails wind to the canyon floor. Raft and boat excursions along the canyon's river bottom are popular. In 2000 the lands north of the western portion of the canyon, an area almost the size of the park, were designated Grand Canyon–Parashant National Monument (1,014,000 acres/410,670 hectares). See National Parks and Monuments (table).

See S. Whitney, A Field Guide to the Grand Canyon (1987); J. W. Krutch, Grand Canyon (1989); S. J. Pyne, How the Canyon Became Grand (1998).

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