Grand Canyon

A 2-billion-year book carved by a river

The Grand Canyon is a giant gorge that the Colorado River carved into rock over millions of years: 446 km long and 1.8 km deep! Its walls have colourful layers — each layer is a page of Earth's history. The rocks at the bottom are 2 billion years old. The canyon is so big you can see it from space.

The Grand Canyon (Arizona) was carved by the Colorado River through the Colorado Plateau over 5–6 million years: 446 km long, up to 29 km wide and 1,857 m deep. Its walls expose more than 40 rock layers — from the Vishnu Schist (1.8 billion years) to the Kaibab Limestone (270 million years); geologists call it an 'open textbook'. Between the layers lies the 'Great Unconformity', where a billion years of record is missing. The canyon has 5 climate zones: desert at the bottom (+45 °C), pine forest and snow at the top. The Havasupai and Hopi peoples have lived here for thousands of years. A national park since 1919, it draws 5 million visitors a year. The condor, America's largest bird, has been reintroduced here.

Fun facts

• The rocks at the bottom of the canyon are 1.8 billion years old — half the age of Earth.
• It can be summer at the bottom of the canyon and winter at the top — 5 climate zones.
• Shout into the canyon and the echo comes back 10 seconds later.