The canyon is up to 1,800 m deep its width at the level of the plateau surface (elevation 2,100–2,400 m) is 8–25 km, but less than 1km where the river waters cut through (at individual spots it is up to 120 m). It extends 320 km downstream from the basin of the Little Colorado. It is one of the deepest canyons in the world. Grand Canyon of the Colorado River, a canyon in the state of Arizona (USA), in the middle course of the Colorado River, on the Colorado Plateau. Pyne, How the Canyon Became Grand (1998). Whitney, A Field Guide to the Grand Canyon (1987) J. See National Parks and Monuments (table). 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). Raft and boat excursions along the canyon's river bottom are popular. Along the forested northern rim and the more accessible southern rim are numerous lookouts, and trails wind to the canyon floor.
The park was enlarged in 1975 to include other areas, such as Marble Canyon and parts of Glen Canyon and Lake Mead. In 1919 an expanded area was designated Grand Canyon National Park (1,217,403 acres/492,876 hectares). government in 1908 as a national monument. The Grand Canyon was set aside by the U.S. explorer John Wesley Powell became the first person to lead a party through the canyon bottom in a boat. (The Hualapai now operate a visitors center, including a skywalk projecting over the canyon rim.) The first European to see the canyon was the Spanish explorer García López de Cárdenas in 1540. The Havasupai people still occupy a part of the canyon, and the Hualapai reservation encompasses much of the south rim. Hundreds of ancient pueblos dot the lower canyon walls and the rim. Plant life on the canyon walls varies from subtropical at the base to subarctic near the rims. 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. 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.
Grand Canyon, 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.