1 Sands and Muds accumulated to form rock strata.
2 The strata were folded into high mountains. Heat and pressure changed both structure and composition of the lower rocks during the folding.
3 Molten masses were forced up into cracks from below. Upon cooling they formed lavas on the surface and granites beneath.
4 During a tremendously long period of time the rivers and rains slowly widened the valleys and wore down the ancient mountains to a great plain near sea level.
As yet no definite traces of either plant or animal life have been found in rocks of the Archean age in Grand Canyon. Though various forms of life may have existed then, and may have been preserved in the original rocks, their record has since been entirely removed by those extreme pressures which altered even the composition and structure of the rocks themselves.
GRANITE IN GRAND CANYON
(THE ARCHEAN ERA)
Within the black, crystalline rocks of the Inner Gorge may be seen many large streaks, bands or irregular masses of a lighter color. From the Canyon rim these appear white, but from nearby they are usually pink. These light colored rocks are granites with a coarse crystalline texture.