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 conservation of the Grand Canyon area, and visited on numerous occasions to hunt and enjoy the scenery.
The canyon, created by the Colorado River over 6 million years, is 277 miles (446 km) long, ranges in width from 4 to 18 miles (6.4 to 24 kilometers), 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. http://en.wikipedia.org/wiki/Grand_Canyon