How Canyons Are Formed — A Scientific Breakdown Canyons are primarily the result of fluvial erosion, tectonic uplift, and differential weathering acting over millions of years. ⸻ 1. Fluvial Erosion (River Incision) Most canyons begin with a river that possesses enough stream power to cut downward into the bedrock. Stream power is controlled by: • Discharge (amount of water flowing in the river) • Gradient (the steepness of the river’s path) • Sediment load (rock and sand carried by the water) As