The Grand Canyon is probably the most famous geologic formation in the world. It is 216 miles long,14–18 miles across, and about a mile deep. The first question most visitors express is, “How did this happen?” Many geologists have tried to answer this question and have proposed different theories as to how the canyon was formed.
Geologists saw the power of moving water through catastrophic failures of dams that breached. In 1889 the Johnstown flood and the 1976 Teton Flood in Idaho, breached dams caused loss of life and showed quick catastrophic geological events. Unfortunately, in geology, invoking catastrophes violates a “sacred rule,” any explanations should involve only processes we see today. This assumption, known as uniformitarianism, still underlies most geological thinking today.