Although
the Western Desert is essentially a flat rocky plateau,
much of its vast expanse is covered by eolian (wind
blown) sand and the Great Sand Sea of Egypt is part
of one of the largest sand-covered areas on earth. The
Great Sand Sea extends from the Libyan border west of
Siwa Oasis in a generally southerly direction touching
the oases of Farafra and Dakhla on the east and ending
at the Gilf Kebir at its southernmost tip.
Sand dunes, which cover 40% of the Western Desert, have
a variety of forms and complexity that depend on the
wind regime and sand abundance. In the north, longitudinal
dunes known as seif (sword) or irq predominate, while
to the south barchan or crescent-shaped dunes are more
common. Some other forms, such as parallel wavy dune
complexes are found but are less common. Dunes move
at a more or less fixed rate in the direction of the
prevailing wind. Thus, the southernmost fingers of the
Great Sand Sea are encroaching on the wadis of Gilf
Kebir. |
