How are canyons carved in mountain regions by rivers?

Canyons form when running water erodes rock vertically faster than side-to-side erosion can widen the valley. In mountain regions, tectonic uplift can raise the land, increasing the river’s gradient and giving it more energy to cut down into bedrock. Sediment carried by the river acts like sandpaper, grinding the channel deeper, while floods can remove loose debris and expose new rock. The Grand Canyon is a famous example, shaped mainly by the Colorado River as the Colorado Plateau rose. Canyon formation is typically measured in millions of years, not thousands.