Section 5 Aeolian Deposits and Erosion Forms

Abstract

Aeolian deposits consist of particles in the range of diameters of 0.02 to 2.00 mm. They have been transported by wind in suspension or traction from regions of sparse vegetation and a large supply of unconsolidated sediments. Aeolian sand deposits, excluding coastal dune systems, cover approximately 5% of the global land area of which 97% occur in large arid zone sand seas (dune fields of regional extent). An additional 10% is covered by silt loess (Fig. 50). 19 Units and 10 Variants are ordered in six Subgroups: Et – Inland deposits: are unconsolidated, unstratified silt sediments (Fig. 50) that occur in the continental heartlands of North and South America, Europe, and Asia. Ef – Duneless deposits: these consist of coarse sand which is not readily formed into dunes (Fig. 51). Er – Erosion forms: are wind-sculpted Units in homogeneous materials (Fig. 52). Ed – Sand dunes: are mounds, ridges or hills aerodynamically shaped by aeolian processes (Figs. 53, 54). Eo – Obstacle dunes: these form where sand-laden wind encounters a topographic barrier. Ec – Coastal dunes: are dunes that occur above high-water marks of sandy beaches.