When did the Colorado River establish its course through the Grand Canyon?

The correct timeframe for when the Colorado River established its course through the Grand Canyon is about 5 to 6 million years ago. This geological event is closely linked to the interplay of tectonic activity and erosion. The Grand Canyon's formation is attributed to significant uplift of the Colorado Plateau alongside extensive erosion caused by the flowing river. As the plateau rose, the river carved into the terrain, creating the deep canyon we see today.

Studies involving the analysis of river sediment and the age of canyon walls have provided evidence for this timeline, supporting the idea that the Colorado River began to cut its current path around 5 to 6 million years ago. This aligns with geological models that indicate a rapid transition from a more level landscape to the complex river system now present. Understanding this period is crucial for grasping the geologic history of the Grand Canyon and the processes that shaped it.