Editing Qattara Depression (section)

==Geography==
[[File:The Qattara Depression, Egypt, Matruh Governate.png|thumb|upright=1.75|Map of the Qattara Depression.<br/> Lower left bound: 28°36'30.74"N 26°14'31.08"E.<br/> Upper right bound: 30°31'1.74"N 29° 8'51.83"E.]]

The Qattara Depression has the shape of a teardrop, with its point facing east and the broad deep area facing southwest. The northern side of the depression is characterised by steep escarpments up to {{cvt|280|m|ft}} high, marking the edge of the adjacent El Diffa plateau. To the south the depression slopes gently up to the [[Egyptian Sand Sea|Great Sand Sea]].

Within the Depression are [[salt marsh]]es, under the northwestern and northern [[escarpment]] edges, and extensive [[dry lake]] beds that flood occasionally. The marshes occupy approximately {{convert|300|km2|sqmi}}, although wind-blown sands are encroaching in some areas. About a quarter of the region is occupied by dry lakes composed of hard crust and sticky mud, and occasionally filled with water.

The depression was initiated by either wind or fluvial erosion in the late [[Neogene]], but during the [[Quaternary Period]] the dominant mechanism was a combination of [[Weathering#Salt-crystal growth|salt weathering]] and [[Erosion#Wind|wind erosion]] working together. First, the salts break up the depression floor, then the wind blows away the resulting sands. This process is less effective in the eastern part of the depression, due to lower salinity groundwater.<ref name="Geomorphology">{{cite journal |url=http://www.sciencedirect.com/science/article/pii/S0169555X01001520 |doi=10.1016/S0169-555X(01)00152-0 |title=The role of salt weathering in the origin of the Qattara Depression, Western Desert, Egypt |year=2002 |last1=Aref |first1=M.A.M. |last2=El-Khoriby |first2=E. |last3=Hamdan |first3=M.A. |journal=Geomorphology |volume=45 |issue=3–4 |pages=181–195 |bibcode=2002Geomo..45..181A |url-access=subscription }}</ref>