Wind action is confined to areas where there is little or no soil and so it mainly operates in desert areas or at beaches. Along with rivers and ice, wind has the ability to erode, transport and deposit material. It can do this only in a very limited way, however, if the surface is protected by vegetation or held together by damp soil. Vegetation and moisture combine to hold the soil in position so this means that wind as an agent of erosion or deposition is only significant in arid regions or along sandy coastal areas in other regions. In these areas the loose surface material which is, for the most part, unprotected by vegetation can be significantly altered by the action of wind. A basic appreciation of how deserts occur and where they are found is helpful in understanding the work of wind. The majority of deserts are found in the subtropical high-pressure regions 15° and 30° north and south of the equator - the Sahara would be typical of this type of desert. Another typical area of desert would be at coastal areas where there is cold ocean current, usually on the western side of land masses, e.g., the Atacama Desert in South America.