Final answer:
The Supai Formation's deposition above the Redwall Limestone suggests a change from a marine to a terrestrial environment, involving deltas and floodplains, influenced by regional tectonics like the Laramide Orogeny.
Step-by-step explanation:
The Supai Formation was deposited on top of the Redwall Limestone, indicating a change in depositional environment in the ancient geologic past. Considering the principles of superposition and Walther's Law, this transition suggests that a non-marine environment with deltas, floodplains, or coastal plains likely deposited the Supai Group of sediments over the marine deposits of the Redwall Limestone. The presence of mudstone, sandstone, and limestone within the Supai Group implies varying conditions such as periodic flooding, changes in sediment supply, and potential shifts in sea level (transgression and regression), as illustrated by the stratigraphic sequences in the Grand Canyon. These changes in depositional conditions coincide with the regional tectonics, such as the uplift related to the Laramide Orogeny, and ultimately led to the deposition of the terrestrial sediments on top of the previous marine limestone.