Types of Aeolian Sand Dunes and Their Formation

The accumulation of windblown sand creates sand dunes which are one of nature’s most dynamics and intriguing phenomena. Sand dunes are found in most climates of the world as coastal dunes and in some arid regions. Grains of sand between 0.062 and 2.0mm in diameter are not cohesive and therefore are easily carried by the wind. Paradoxically, finer grains of silt and clay (< 0.050mm) are cohesive and can resist wind erosion. This property of sand is reflected in the wind threshold speed curve for sand transport (Fig. 17.1) explaining why dune sand, in most cases, is composed of fine particles between 0.125—0.250 mm.