Mountain

A mountain is a natural elevation of the Earth's surface that rises significantly above the surrounding land. Mountains can form in several ways, but many develop where tectonic plates move toward one another and compress, fold or uplift layers of rock. Others are built by volcanic activity, while erosion can also shape existing highlands into their present forms.

There is no single worldwide height that officially separates a mountain from a hill; the distinction often depends on local geography and common usage. Mountains may occur alone, but they are frequently found in groups called ranges. Their slopes, peaks and valleys can have very different climates from the nearby lowlands. As altitude increases, temperatures generally decrease, and conditions may become colder and windier.

Mountain environments support a wide variety of life, although the species found there depend strongly on altitude, climate and location. Vegetation often changes from forests at lower elevations to grasslands, shrubs and more sparsely vegetated areas higher up. At great elevations, permanent snow and ice may occur where temperatures remain low enough. Mountains are also important sources of freshwater because snow and ice, together with rainfall, can feed rivers and lakes.

They influence weather patterns and provide habitats for species adapted to steep terrain and changing conditions. People have long lived in and around mountain regions, using them for farming, grazing, forestry, tourism and other activities. At the same time, mountain ecosystems can be vulnerable to climate change, erosion and human pressure, making their protection important for both biodiversity and water resources.