Topic summary
Sand sea
Extracted from the Wikipedia article Erg (landform).
Description
Entire ergs and dune fields tend to migrate downwind as far as hundreds of kilometers from their sources of sand. Such accumulation requires long periods of time. At least one million years is required to build ergs with very large dunes, such as those on the Arabian Peninsula, in North Africa, and in central Asia. Sand seas that have accumulated in subsiding structural and topographic basins, such as the Murzuk Sand Sea of Libya, may attain great thicknesses (more than 1000 m) but others, such as the ergs of linear dunes in the Simpson Desert and Great Sandy Desert of Australia, may be no thicker than the individual dunes superposed on the alluvial plain. Within sand seas in a given area, the dunes tend to be of a single type. For example, there are ergs or fields of linear dunes, of crescentic dunes, of star dunes, and of parabolic dunes, and these dune arrays tend to have consistent orientations and sizes.