The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona. It is largely contained within the Grand Canyon National Park, the 15th national park in the United States. 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. It is considered a Wonder of the Natural World.
The Grand Canyon is 277 miles long, up to 18 miles wide and attains a depth of over a mile. 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 Grand 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 its present-day configuration.
(Source: Wikipedia, Image: B. Rosen)