How were the largest canyons and the deepest valleys created?

The largest canyons and deepest valleys were primarily formed through a combination of geological processes, including erosion, tectonic activity, and weathering. Rivers cut through rock and soil over millions of years, carving out canyons as they flow and erode the landscape. Tectonic forces can uplift land, creating valleys and deepening existing ones. Additionally, glacial activity in some regions has also contributed to shaping these features by grinding down rock and sediment.