Final answer:
The Grand Canyon was primarily formed through water erosion by the Colorado River. Geological evidence supports the process beginning millions of years ago, shaping the extensive stratigraphy and exposing ancient rock layers.
Step-by-step explanation:
The primary agent of erosion responsible for the formation of the Grand Canyon is water erosion by the Colorado River. Over millions of years, the river has cut through layers of rock, forming the vast and deep canyon we see today. The process began around 5 to 6 million years ago when the Colorado River established its course through the area and started eroding the underlying rock. The canyon's formation involves other geologic processes such as tectonic activity and the erosion of tributaries, which continue to shape the landscape. The exposed rock layers provide a record of the Earth's history, with some sections of the canyon revealing rocks that are billions of years old.
Examining the stratigraphy, or the layering of rocks, and the faults that are cross-cut by the river, one can see evidence supporting the timeline of the canyon's formation. The presence of various rock formations, faults, and the erosion pattern are descriptive of an eroding landscape shaped predominantly by the flowing water of the river.
In comparison, formations like 'The Wave' at Vermillion Cliffs, while also a product of erosion, have been shaped by both water and wind erosion, which shows the distinctive roles different agents of erosion play in shaping geographical features.