Mountain

A mountain is a landform that extends above the surrounding terrain in a limited area, with a peak. A mountain is generally steeper than a hill, but there is no universally accepted standard definition for the height of a mountain or a hill although a mountain usually has an identifiable summit.



High mountains, and mountains located closer to the Earth's poles, have elevations that exist in colder layers of the atmosphere. They are consequently often subject to glaciation and erosion through frost action. Such processes produce the popularly recognizable mountain peak shape. Some of these mountains have glacial lakes, created by melting glaciers; for example, there are an estimated 3,000 glacial lakes in Bhutan.



A mountain is usually produced by the movement of lithospheric plates, either orogenic movement or epeirogenic movement. The compressional forces, isostatic uplift and intrusion of igneous matter forces surface rock upwards, creating a landform higher than the surrounding features. The height of the feature makes it either a hill or, if higher and steeper, a mountain. The absolute heights of features termed mountains and hills vary greatly according to an area's terrain. The major mountains tend to occur in long linear arcs, indicating tectonic plate boundaries and activity. Two types of mountain are formed depending on how the rock reacts to the tectonic forces – block mountains or fold mountains.