Wednesday, 3 December 2014
The Grand Canyon , is a steep-sided canyon carved by the Colorado River in the state of Arizona in the United States. It is contained within and managed by Grand Canyon National Park, the Hualapai Tribal Nation, the Havasupai Tribe and the Navajo Nation. President Theodore Roosevelt was a major proponent of preservation of the Grand Canyon area, and visited it on numerous occasions to hunt and enjoy the scenery. The Grand Canyon is 277 miles (446 km) long, up to 18 miles (29 km) wide and attains a depth of over a mile (6,000 feet or 1,800 meters). Nearly two billion years of 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 Grand Canyon are the subject of debate by geologists, recent evidence suggests that 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 its present-day configuration.