Plain

A plain is a broad area of land that is generally flat or gently rolling, with relatively little change in elevation across large distances. Plains can occur at different elevations and in many environments, including inland regions, along coasts, and around rivers. Some formed when sediments carried by rivers, wind, glaciers, or water from lakes accumulated over long periods.

Others developed through the erosion of older landscapes or the movement and deformation of Earth's crust. River plains, for example, often contain layers of sediment deposited during floods and changes in the course of a river. Coastal plains may have been shaped by sediments and changes in sea level. Because their surfaces are often relatively easy to cross and cultivate, plains have played an important role in human settlement and agriculture.

The characteristics of a plain depend on its origin, climate, soil and water availability. Fertile plains supplied by rivers can support intensive agriculture, while dry plains may contain grasslands, shrublands or sparse vegetation. Some plains are home to large wetlands, which can store water and provide habitats for many species. Others contain major cities, roads and industrial areas because their relatively level terrain makes construction and transport easier.

Plains are not necessarily completely flat, and many include gentle slopes, small hills, valleys or shallow depressions. They can also be affected by floods, droughts, soil erosion and changes in land use. Protecting soils, managing water carefully and preserving natural vegetation are important for maintaining the ecological and agricultural functions of these extensive landscapes.