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Grand Canyon (Arizona, U.S.A)
Holding true to its name, the Grand Canyon really is one of the most grand and impressive canyons (and geological sites) in the world. It is ~ 450 km long and up to 1.5 km deep in areas. One of the reasons it is so impressive is that it literally is a slice into hundreds of millions of years of time captured in the rock record. The rocks at the bottom of the canyon formed first and are Proterozoic age… over 1 billion years old. Whereas, the rocks above it towards the top formed later and are Mesozoic age… only a few hundred million years old. You can see this sedimentary rock history (stratigraphic column) beautifully exposed on the walls. Its carved canyon shape is due to the retreat and erosion from the Colorado river over time.
