geomorphology

Branch of geology developed in the late 19th century, dealing with the morphology, or form, of the Earth's surface; nowadays it is also considered to be an integral part of physical geography. Geomorphological studies investigate the nature and origin of surface landforms, such as mountains, valleys, plains, and plateaux, and the processes that influence them. These processes include the effects of tectonic forces, weathering, running water, waves, glacial ice, and wind, which result in the erosion, mass movement (landslides, rockslides, mudslides), transportation, and deposition of rocks and soils. In addition to the natural processes that mould landforms, human activity can produce changes, either directly or indirectly, and cause the erosion, transportation, and deposition of rocks and soils, for example by poor land management practices and techniques in farming and forestry, and in the mining and construction industries.

Geomorphology deals with changes in landforms from the present to the geologic past, and in spatial scales ranging from microscale to mountains. For example, the formation of mountain ranges takes place over millions of years, as the Earth's crust cools and solidifies and the resulting layers, or plates, are folded, uplifted or deformed by the seismic activity of the underlying magma (see plate tectonics). The gouging out of river valleys by glacial erosion is a gradual process that takes place over thousands of years. Conversely, volcanic eruptions, by the ejection of rocks and gases and the rapid flow of molten lava down a mountainside, create rapid changes to landforms, as with the volcanic eruptions on the island of Montserrat in the West Indies. Similarly, the eruption of undersea volcanoes can result in the sudden birth of islands, while the consequent and rapidly moving tidal waves (tsunamis), can produce the unexpected inundation and destruction of low-lying coastal regions in their path.