The great canyon of Colorado

The Great Canyon is a steep-sided canyon carved by the Colorado River in the United States in the state of Arizona. It is largely contained within the Great Canyon National Park, one of the first national parks in the United States. President Theodore Roosevelt was a major proponent of preservation of the Great Canyon area, and visited it on numerous occasions to hunt and enjoy the scenery.
The Great Canyon is 277 miles (446 km) long, up to 18 miles (29 km) wide and attains a depth of over a mile (1.83 km) (6000 feet). Nearly two billion years of the Earth’s geological 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. While the specific geologic processes and timing that formed the Great Canyon are the subject of debate by geologists,recent evidence suggests the Colorado River established its course through the canyon at least 17 million years ago. Since that time, the Colorado River continued to erode and form the canyon to the point we see it at today.

The Great Canyon Skywalk is a transparent horseshoe-shaped cantilever bridge and tourist attraction in Arizona near the Colorado River on the edge of a side canyon in the Great Canyon West area of the main canyon. USGS topographic maps show the elevation at the Skywalk’s location as 4,770 ft (1,450 m) and the elevation of the Colorado River in the base of the canyon as 1,160 ft (350 m), and they show that the height of the precisely vertical drop directly under the skywalk is between 500 ft (150 m) and 800 ft (240 m).
Before European immigration, the area was inhabited by Native Americans who built settlements within the canyon and its many caves. The Pueblo people considered the Great Canyon (“Ongtupqa” in Hopi language) a holy site and made pilgrimages to it. The first European known to have viewed the Great Canyon was García López de Cárdenas from Spain, who arrived in 1540.