Erosion, volcanoes and much more!

What do you get if you mix erosion, volcanoes, a hot and dry climate and the Colorado River? If you’re really lucky and have a lot of time – at least a million years – you get the Grand Canyon. 
Located in Arizona, this huge hole in the ground shows the Earth – right down to the bone.
Erosion takes a long time to turn a desert floor into a Grand Canyon. Some scientists believe it took as long as six million years. Others believe it was much faster, taking only one million years. Either way, it was a long time!

http://www.kidsgeo.com/geology-for-kids/0060-weathering.php