Canyon, also spelled cañon, is a deep valley with steep sides. A narrow canyon with nearly vertical walls or cliffs is called a gorge, ravine, or chasm.
Most canyons have been formed by rivers or streams eroding (wearing away) rock. One of the most spectacular examples, the Grand Canyon, in Arizona, was carved by the Colorado River over millions of years. The Grand Canyon has an average depth of 1 mile (1.6 kilometers). Glaciers also have shaped canyons in mountainous regions. Such canyons usually have a U shape. Stream-cut canyons typically have a V shape. Narrow bays called fiords have formed on coastlines where the sea level has risen to flood canyons that were cut by glaciers. Canyons also may form as a result of faulting (shifts in Earth’s crust). Faulting has created many of the large canyons on the ocean floor.
