The downland consists of two ranges of chalk hills of limestone deposits formed by sometimes microscopic shells of marine organisms. Downland is usually form where bands of chalk reach the surface at an angle. As they are slowly eroded a steep scarp slope forms where the rock has been removed, and a shallow dip slope remains where the rock has not been eroded. Chalk is permeable and can hold large quantities of water, removing the need for large reservoirs in areas with chalk hills. The height of the water table in chalk hills rises in winter and falls in summer, and chalk areas often contain bournes - rivers which are dry in the summer, and in England many villages named Winterbourne can be found in the South Downs, Dorset Downs and Salisbury Plain.
Chalk downland is typically calcareous grassland, a habitat formed by grazing animals. Chalk downland is often unspoilt and rural because it is often unsuitable for agriculture, horticulture or building.
Chalk downland can be found in many places, including:
In the United Kingdom: