A gorge is a narrow valley with steep, rocky walls located between hills or mountains. It is created by the weathering and erosion of a river over millions of years. Gorges have steep banks where the river has cut through the earth. They are typically formed in areas composed of limestone rock. Most gorges are located between mountains, hills, or near-desert plateaus, at the point where a river cuts a channel into the land. Gorges are more common in dry areas because erosion is common in arid places. Some gorges are so large they are visible from space, such as the Grand Canyon. The term "gorge" was derived from the French word meaning "neck" or "throat". The word canyon is generally used in North America, while the words gorge and ravine are used in Europe and Oceania, though gorge and ravine are also used in some parts of North America. In Canada, a gorge is usually narrow while a ravine is more open and often wooded.