The Grand Canyon, in northern Arizona, United States, is an exceptionally deep, steep-walled chasm, excavated by the Colorado river, over millions of years.
It is 446 kilometres long, ranges from 0.5 to 29 kilometres in width, and reaches a depth of more than 1.6 kilometres.
This magnificent example of erosion is geologically significant because of the thick sequence of beautifully preserved rocks held in the walls of the canyon. The rocky splendour attracts close to 5 million visitors per year and is widely proclaimed as one of the Seven Wonders of the Natural World.
The United States government designated the Grand Canyon a National Park in 1919. The park was inscribed as a World Heritage Site by UNESCO in 1979.