The Grand Canyon is a textbook example of how a “rejuvenated” river interacts with an uplifted plateau. The Colorado Plateau underwent significant tectonic uplift during the Cenozoic Era. As the plateau rose, the Colorado River maintained its course by cutting deeper into the earth, exposing nearly two billion years of geological history in its walls. This process, known as “downcutting,” demonstrates the immense power of fluvial (river) erosion on high-altitude tablelands. Geographically, the plateau’s arid climate helps preserve the sharp, vertical walls of the canyon, preventing them from being smoothed over by heavy rainfall.