How Is a Canyon Formed?

A canyon is a deep cut in the earth with steep sides and a relatively small bottom. While canyons can be massive in size, the size of the canyon bottom is generally extremely small when compared to the height of the sides. When compared to what's typically called a "ravine," canyons are typically much deeper and difficult to access. A canyon is a steep gorge with high sides and a minimal valley floor. While some consider a canyon to be a formation equal to a valley, the two aren't actually interchangeable. Canyons are significantly steeper than valleys. One of the most noted canyons in the world is the Grand Canyon in the United States.

Much like valleys, canyons are generally formed strictly through erosion. Typically formed by rivers, a few are also caused by massive movement of the Earth's tectonic plates. The two canyon types are similar, but do differ in their general form. Typically, a canyon forms when a river's course begins eating away at the underlying rock strata. As the water flows, it carries away much of the material making up the canyon's floor. As the water continues along its course, the canyon becomes deeper and deeper. The further the canyon progresses and the deeper it gets, the faster the erosion process becomes. The reason for this is that the canyon walls begin acting as a sluice, channeling the force of the water into a progressively smaller area.This is why canyons tend to be much wider at the top than they are at the bottom. The steeply sloping sides are caused by the water carrying dirt and rock away from the canyon walls, toward the far end of the river's course. As the canyon walls attain a greater surface area, they also pick up erosion from wind and rain, as well. As the canyon grows deeper, the exposed rock strata becomes more pronounced and the underlying geography of the area becomes visible.

The canyon walls are typically visible as layers of rock strata. Because the harder rock wears away significantly slower than the softer materials, the hard rock of the canyon walls is more readily visible along the canyon walls. Geologists study these rock strata to track geological events through the ages. These rock strata can assist geologists in tracking the progression of ice ages and other geological phenomena.