The Grand Canyon is a steep-sided canyon carved by the Colorado River
in the United States in the state of Arizona.It is largely contained within
the Grand Canyon National Park,one of the first national parks in the United
States.
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 / 1,800 metres).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.
