With layers of red, pink, purple, brown, green, gray, and yellow, the rocky walls of the Grand Canyon look like a box of melted crayons.
No powerful cranes, noisy drills, or enormous shovels constructed the canyon. Instead, it was created by the mighty Colorado River. Of course, it had some help: small streams and tributaries, plus wind, rain, snow, and ice, as well as Earth’s shifting tectonic plates.
The canyon is a slow and steady work in progress that has continued for more than 6 million years.
