The rocks of the Grand Canyon reveal an ancient geologic history that is rich and complex. All three basic rock types with sedimentary, metamorphic and igneous origins are represented within its walls, terraces, mesas and buttes.

A vertical mile of formations underlying its rim have been exposed by the erosional processes creating it, revealing strata and formations ranging in age from mid Phanerozoic Eon (about 250 million years old) at the rim, to mid Proterozoic Eon (about 1.75 billion years old) along deep cut portions of the inner gorge where the Colorado River runs.

The still ongoing erosion carving the Grand Canyon below its rim and exposing these primordial rocks is very young in terms of geologic time and was triggered by an uplift 'pulse' within the Colorado Plateau region that began approximately 6 million years ago.