A gorge, also sometimes referred to as a canyon, is a deep channel created by millions of years of erosion by a river and other forms of weathering. The term "gorge" was derived from the French word meaning "neck" or "throat." The most well-known gorge in the world is the Grand Canyon, which is located in US state of Arizona and was formed by the Colorado River. It is 6,000 feet deep, 277 miles long, and has a width of 15 miles at its widest point. Other notable gorges include the Victoria Falls Gorge, Canyon Lake Gorge, Yarlung Zangbo Grand Canyon, Three Gorges, Olduvai Gorge, Talari Gorges, Macocha Gorge, Gorge de Verdun, New River Gorge, Columbia River Gorge, and Gorges of Finger Lakes.
Characteristics of a Gorge
Gorges are formed by an existing river or a former river that has dried up. Most gorges are located between mountains, hills or near-desert plateaus, at the point where a river cuts a channel into the land. Gorges form due to water erosion, weathering, geologic uplift, or the movement and melting of glaciers. Generally, they are more common in dry areas, because erosion is common in arid places. Another feature of gorges is that they are typically formed in areas composed of limestone rock. Limestone is soluble, which encourages the formation of cave systems on rocks. Subsequently, the collapse of rocks results in the creation of gorges.
A gorge can also be formed when an earthquake causes geologic uplift. This uplift causes some parts of Earth's surface to be more elevated than the surrounding area. When rivers flow across these uplifted areas, waterfalls are formed. Meanwhile, the erosion of softer layers of rock occurs, leading to the collapse of a river bed, which formes a gorge. For example, the Macocha Gorge in the Czech Republic was formed due to the erosion of the Punkva River, which resulted in the collapse of an underground cave. Gorges can also be formed by glaciers, which become exposed when a glacier melts.
Types of Gorges
There are three primary types of gorges: slot canyons, box canyons, and submarine canyons. A slot canyon is a narrow gorge with smooth walls, box canyons are open on only one side, while submarine canyons are formed due to landslides and turbidity currents, rather than weathering or erosion.
Georges can have economic, recreational, and geological benefits. For example, the rivers that form and flow through a gorge can be harnessed through hydroelectric dams for the production of electricity. The Three Gorges Dam in China has 26 turbines that generate 18,000 megawatts of electricity for Shangai and other cities in the region. Gorges can also form waterways that can be navigated by freight ships. Additionally, gorges and rivers can create opportunities for recreational activities like wind sailing, whitewater rafting, and hiking. Many geological discoveries have occurred due to the creation of gorges, as these canyons expose rocks that existed thousands of years ago. For example, the Olduvai Gorge in Tanzania resulted in the discovery of fossils and rocks that dated as far as two million years.