The Grand Canyon is relatively young geologically. Most scientists believe the river began its work of erosion about six million years ago. Coupled with the downward cutting of the river has been a general rising of the Colorado Plateau, which has added its effect to the action of the river. Although the canyon itself is of comparatively recent origin, the rocks exposed in its walls are not. Most of the strata were originally deposited as marine sediment, indicating that for long periods of time the canyon area was the floor of a shallow sea.

Grand Canyon is unmatched throughout the world for its overwhelming size and intricate colors…