The Grand Canyon is a steep-sided gorge carved by the Colorado River in the United States 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.

View from the South Rim.

A map of the Grand Canyon and surrounding areas, circa 1908.Longstanding scientific consensus has been that the canyon was created by the Colorado River over a six million year period. The canyon is 277 miles (446 km) long, ranges in width from 4 to 18 miles (6.4 to 29 km) and attains a depth of over a mile (1.83 km)(6000 feet).[1] 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. The "canyon began in the west, followed by another that formed in the east. Eventually, the two broke through and met as a single majestic rent in the earth some six million years ago. [...] The merger apparently occurred where the river today bends to the west, in the area known as the Kaibab Arch."[2]