How Canyons are Formed

Canyons are deep gouges in the Earth characterized by steep sides and a narrow base. These landforms can be massive, occupying miles of territory. Canyons are usually much deeper and more difficult to access than ravines or other deep landforms.  One of the best and most famous canyons is the Grand Canyon in the United States.

Like many similar landforms, canyons are generally formed by erosion.  Typically, this erosion is done by rivers.  It should be noted, though, that a few canyons are formed by massive and quick movements of the Earth’s tectonic plates, typically occurring during an earthquake. These two types of canyons are similar, but there are some key differences in their appearance.

Most commonly, a canyon will form when a river’s flow starts to erode the rock underneath. In other words, as the river flows, it will wash away a lot of the rocky material.  Over time, this will start to form the floor of the canyon. As the water continues to flow, the canyon will become deeper. As time progresses, the canyon will get deeper.  As the canyon gets deeper the erosion process becomes faster.

The canyon gets deeper because as the river starts to form a gouge, the walls of the canyon begin acting as a sluice.  This channels the force of the water into a smaller and smaller area. This channeling is also why canyons tend to be much wider at their top than they are at their base.

The steeply sloping sides of a canyon are caused by the water that carries dirt, sediment, and rock away from the newly formed walls of the canyon. This sediment is carried towards the end of the course of the river. As the canyon walls increase in surface area, they will also be eroded by wind and rain. Additionally, as the canyon becomes deeper, the exposed rock layers become more visible.

Canyons that are formed by earthquakes are typically much deeper and have a more narrow base than other canyons.  These formations also have walls that are jagged, unlike the smooth walls on other canyons.

The canyon walls are usually visible as various layers of rock. Because the harder rock layers wear away much slower than other, softer materials, the hard rock portions of canyon walls are more visible along the canyon walls. These rock layers have assisted geologists in tracking the history and progression of ice ages, warming trends, and other geological phenomena.