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.
The Grand Canyon is gigantic. It is the eleventh largest national park, but is the fourth largest in the continental US. It is 277 miles long. The width of the park varies from one end to the other, but in some places it is 18 miles wide. All of the acreage totals 1904 square miles! But the Grand Canyon is not just big around. It is also deep. It averages one mile in depth, but parts of it are much deeper than that. In fact, it is so big and so deep that it can be seen from space!
How did this great gash in the Earth happen? Water is responsible for most of the erosion. Lots of water flows through the Colorado River, and has for a long time. But when it rains in the desert-country of the Grand Canyon, the baked dirt quite often cannot take the moisture in. The rainwater begins to run down toward the river, making flash floods common. The flood water moves so fast that it topples rocks and boulders in its path. Dirt is swept along, leaving behind only hard rock formations. During the harsh winters of the region, water seeps in the tiny cracks and crevices of the rocks. When it freezes, it gets bigger and cracks the rocks even more. Wind also adds to the erosion process of the Grand Canyon, which is still changing every year.
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!
Different types of rocks form the Earth. In the Grand Canyon, each layer can be seen. The strata (several layers, one atop the other) are more clearly displayed here than anywhere else on Earth. Scientists can get a clear picture of each layer. These layers of rock rise one full mile above the Colorado River.
