The Grand Canyon is the result of a distinct and ordered combination of geologic events. The story begins almost two billion years ago with the formation of the igneous and metamorphic rocks of the inner gorge. Above these old rocks lie layer upon layer of sedimentary rock, each telling a unique part of the environmental history of the Grand Canyon region.
Then, between 70 and 30 million years ago, through the action of plate tectonics, the whole region was uplifted, resulting in the high and relatively flat Colorado Plateau.
Finally, beginning just 5-6 million years ago, the Colorado River began to carve its way downward. Further erosion by tributary streams led to the canyon’s widening.
Still today these forces of nature are at work slowly deepening and widening the Grand Canyon.