Dune is a mound or ridge of loose sand that has been deposited by the wind. Dunes are common in all sandy regions. They are found along seacoasts, near rivers and lakes, and in deserts. Dunes may be long and narrow or shaped like a crescent. Some have three or more ridges that extend from a high central peak. In some areas, large dunes reach heights of 1,000 feet (300 meters).
Most dunes are found in large groups known as dune fields. Extremely large areas of dunes in the Sahara and other large deserts are called sand seas. Many dunes migrate across the land as the wind removes sand grains on one side of the dune and deposits them on the other side. Migrating dunes can block highways, bury houses, and destroy agricultural land.
Notable dune areas in the United States include Cape Cod in Massachusetts, Indiana Dunes State Park in Indiana, and Great Sand Dunes National Park in Colorado. The largest dune area in North America is the Nebraska Sand Hills. Other sites are White Sands National Park in New Mexico and Death Valley National Park and the Imperial Valley, both of which are in California.
See also Desert ; Great Sand Dunes National Park .
