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Film summary
Learn how the Colorado River carved this incredible land formation, revealing nearly two billion years of the Earth's geological history in the process.Key facts
- The Grand Canyon is a gorge 2km deep, 29km wide and 446km long.
- Over 75 million years ago, the Pacific plate and the North American plate collided, forming mountain ranges.
- The Colorado river, traveling from the Rocky Mountains, cut through the rock to form the beginnings of the Grand Canyon.
- Flash floods and freeze-thawing also played a part in the formation of the Grand Canyon over the course of 50 million years.
Transcript
The Grand Canyon, Arizona, USA.
The Grand Canyon,
Arizona
A gorge nearly 2km deep, 29km wide and 446km long.
Up to 1.83km deep
Up to 29km wide
446km in length
Located on the Colorado Plateau, the Colorado river cuts through this beautifully preserved canyon - exposing rocks over 2 billion years old.
But how did the Grand Canyon form?
75 million years ago
Around 75 million years ago, two huge pieces of the Earth's crust - the Oceanic Pacific plate and the North American plate - pushed together, creating huge mountain ranges.
As glaciers retreated and advanced between ice ages, sea levels would rise and fall - washing over the mountains and eroding the rock.
With rainfall simultaneously eroding the peaks, a level highland was created – a huge plateau.
At the same time, layers of sedimentary rock and ancient fossils were deposited by the sea.
60 million years ago
Around 60 million years ago, the Colorado river began to form in the Rocky Mountains - 2300km away.
Over millions of years, the river and its estuaries made their way across the landscape, eventually reaching the Colorado Plateau.
Slowly, the water cut through the rock to form a narrow channel – the beginning of the Grand Canyon.
It took the river over 50 million years from forming in the mountains to cut a channel through the plateau.
Because the rock was so dry, flash floods swept huge pieces of rock into the river - widening the channel.
Ice also had its part to play, freezing in cracks and splitting the rock in winter to create side channels.
And, over millions of years, the Canyon grew over 29km wide.
Tectonic plate movement, mountain ranges, ice ages, and millions of years of erosion combine to form one of the most recognizable landscapes on Earth – The Grand Canyon.
