The sedimentary rocks of the Ouseir area belong to the Upper Cretaceous, lower Middle Eocene, Oligocene, Miocene, Pliocene and Quaternary. The Cretaceous-Oligocene rocks exist in the form of faulted synclines, while the Miocene and younger deposits crop out along the Red Sea coast as a simple monocline.
The area under study is affected by the following six main trends of structural lineations, arranged in decreasing abundance and significance: NW-SE, NNW-SSE, WNW-ESE, NE-SW, N-S and E-W. A high degree of preference in orientation, a low degree of scattering and a low density of the structural lineations, due to well-defined fault sets, are noticed in the area occupied by the sedimentary rocks along the Red Sea coast and the Duwi area. The opposite relations are noticed in the area occupied by the basement rocks, where the degree of scattering and the average density of the structural linea¬tions are high, due to multi-directioned fault sets.
The drainage net is characterized by the Following four main preferred trends, arranged in decreasing significance: NW-SE, NE- SW, N-S and E-W. Other trends are locally noticed oriented NNW¬-SSE and WNW-ESE The surface drainage lines in the western part of the area, which is occupied by the basement rocks, are believed to be structurally controlled, while in the eastern part of the area the drainage lines within the sedimentary rocks are controlled by gravity, lithology and structures.