Slow Process
The Colorado River then surged across the plateau for millions of years, bringing debris with it that wore away the granite beneath the surface. It also began to gradually carve a downward course through the sedimentary, metamorphic, and igneous layers as it moved downward. And when the exposed banks were eroded, a canyon with a fast-flowing stream formed at the bottom of the canyon.
Slow Process
Ice Ages
As time passed, the mighty Colorado River continued to carve its way through the mountainous terrain below. Afterwards, beginning approximately two million years ago, a sequence of ice ages occurred. With increasing precipitation, the river’s current grew even stronger, allowing it to carve an even deeper groove into the old rock beneath its surface. The Grand Canyon was formed as a result of this groove, which you may have guessed.
Ice Ages
