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Facts about Sand Dunes for Kids

Dunes occur in different forms and sizes, formed by interaction with the flow of air or water.Most kinds of dunes are longer on the windward side where the sand is pushed up the dune and have a shorter “slip face” in the lee of the wind.

  • A “dune field” is an area covered by extensive sand dunes.
  • Some coastal areas have one or more sets of dunes running parallel to the shoreline directly inland from the beach.
  • In most cases the dunes are important in protecting the land against potential ravages by storm waves from the sea.
  • Although the most widely distributed dunes are those associated with coastal regions, the largest complexes of dunes are found inland in dry regions and associated with ancient lake or sea beds.
  • In ancient times, words cognate to “dune” probably had the meaning of a built-up hill or citadel fortification.
  • Due to widespread human population expansion, dunes face destruction through land development and recreational usages, as well as alteration to prevent the encroachment of sand onto inhabited areas.
  • A group of dunes moved more than 100 meters per year between 1954 and 1959 in the China’s Ningxia Province, and similar speeds have been recorded in the Western Desert of Egypt.
  • Radially symmetrical, star dunes are pyramidal sand mounds with slipfaces on three or more arms that radiate from the high center of the mound.
  • Parabolic dunes are dependent on the vegetation that covers them—grasses,shrubs,and trees, which help anchor the trailing arms.
  • They can also originate from beach sands and extend inland into vegetated areas in coastal zones and on shores of large lakes.
  • Longitudinal dunes (also called Seif dunes, after the Arabic word for “sword”), elongate parallel to the prevailing wind, possibly caused by a larger dune having its smaller sides blown away.
  • In the southern third of the Arabian Peninsula, a vast erg called the Rub’ al Khali or the Empty Quarter, contains seif dunes that stretch for almost 200 km and reach heights of over 300 m.
  • Should the strong wind then return the exaggerated wing will further extend so that eventually it will be supplied with sand when the prevailing wind returns.
  • On a seif dune the slip face develops on the side facing away from the strong wind, while the slip face of a barchan faces the direction of movement.
  • Compound dunes are large dunes on which smaller dunes of similar type and slipface orientation are superimposed, and complex dunes are combinations of two or more dune types.
  • Cross-bedded layers of stacks of lithified dunes can produce the cross-hatching patterns, such as those seen in the Zion National Park in the western United States.
  • A slang term that is used in the Southwestern States (of the US) for those consolidated and hardened sand dunes is “slickrock”, a name that was introduced by pioneers of the Old West because their steel-rimmed wagon wheels could not gain traction on the rock.
  • As the sand grains get trapped they start to accumulate, starting dune formation.
  • The wind then starts to affect the mound of sand by eroding sand particles from the windward side and depositing them on the leeward side.
  • Leaching occurs on the dunes, washing humus into the slacks, and the slacks may be much more developed than the exposed tops of the dunes.
  • Warren Dunes State Park and Sleeping Bear Dunes National Lakeshore, Michigan, on the east shore of Lake Michigan.