Vol 5 Life in the Desert ... Introduction ... Sand dunes
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Introduction

Sand dunes

Sand dunes cover around 20% of the world’s deserts.
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Sand dunes are often called ‘seas of sand’, an appropriate name because the winds move and shape the sand so that the terrain changes constantly. The largest continuous expanse of sand is the Empty Quarter or Rub Al Khali, part of the Arabian desert covering over 250,000 sq miles. The largest dune areas in North America are west of Yuma, Arizona and at White Sands National Monument in New Mexico.

Sand seas consist of two distinct areas: flat, duneless regions and the dunes themselves which may be anything from 3 feet to 1,200 feet high. Winds blow dunes into variety of shapes; the best-known forms are horseshoe-shaped barchans, linear dunes and star dunes. The animation on this page shows how the different shaped dunes are formed. Star dunes are quite stable, while barchan dunes may move as much as 66 feet each year.