How did the Grand Canyon form?

The exact processes that formed the Grand Canyon remain a compelling puzzle. But studies suggest this giant gorge was cut by flowing water just a few million years ago – a blink in geological time. The canyon’s rocks have a much longer history – the oldest are around 2 billion years old.

Perhaps 30-70 million years ago, these rock layers were uplifted to form the high, flat Colorado Plateau. There are several theories explaining how and why this uplift happened. Around 5-6 million years ago, the Colorado River changed its course and began to carve down through the plateau.

The river uses sediment and rocks like chisels and sandpaper to chip away its channel. It has tremendous erosive power because it is fast flowing with a large volume, enabling it to carry a large amount of debris. Arizona’s arid climate means rock is unprotected by vegetation, making it more susceptible to erosion.

The Grand Canyon

The Grand Canyon’s layers (click to zoom)

High-rise wildlife

Five of North America’s seven life zones – areas with similar plants and animals – appear within the Grand Canyon’s one-mile high walls. While desert scrub like cacti are found close to the river, a spruce-fir forest covers the North Rim above 2,500m.

More than 1,500 plant, 355 bird, 89 mammal, 56 reptile and amphibian, and 17 fish species are found around the canyon. Other wildlife species are rare or protected. For example, the Californian condor is among the world’s rarest birds.

The Grand Canyon by numbers

Average depth: 1 mile

Length: 277 river miles

Minimum width: 600ft

Maximum width: 18 miles

Age: 2 billion years

Vistors per year: 4.5 million

EXCLUSIVE OFFER FOR US READERS

Subscribe today and get 13 issues for just £40 – to take advantage of this bargain just click here

 

Happy 4th July, and cheers from across the pond! via GIPHY

 

Discover more amazing natural wonders in the latest issue of How It Works. It’s available from all good retailers, or you can order it online from the ImagineShop. If you have a tablet or smartphone, you can also download the digital version onto your iOS or Android device. To make sure you never miss an issue of How It Works magazine, make sure you subscribe today!

Plus, make sure you also check out our digital-only specials, such as Amazing InventionsExplore Mars and A Guide To The Galaxy, available to download onto your digital device now!

How do glaciers form? 

Earthquake facts: 5 things you never knew about earthquakes

How do waterfalls form?