The geological mapping, landstat images, and detailed sedimentological analysis through measurements of 10 stratigraphic columnar sections, have revealed the presence of four facies associations among the Pre-Eonile and Eonile sediments along the Egyptian Nile west of Sohag. These reflect the co-effect of local and regional tectonics, changes of the catchment areas and paleoclimatology, and were related to four successive tectono-sedimentary stages of the earliest Egyptian Nile evolution as follows:-
1) Stream flow- dominated alluvial fans and braided plain conglomerates, dominated by sedimentary clasts. (association A). These were deposited in a NW structural graben by northwestward- flowing paleorivers after uplift of the Red Sea Highlands southeast of Egypt, associated with the first phase of the Red Sea rifting.
2) Channeled sandstones followed upwards by overbank-flood plain siltstones (association B) coming also by northwestward- flowing paleorivers, and were deposited in an asymmetric graben with its depocenter to the west related to local NW and N-trending syn-depositional faulting.
3) Braided-plain conglomeratic sandstones and fluvial channels sandstones, followed upwards into Sheet flood conglomerates and sandstones and debris to stream flow-dominated alluvial fans conglomerates (collectively association C), sourced from east and southeastward uplifts. These were laid down during the enlargement of the graben which occurred due to back-stepping of NW and NE normal faults.
4) Confined channeled conglomerates and sandstones, and stream to debris flow- dominated alluvial fans conglomerates, composed of mixed sedimentary and basement clasts (association D), derived from northeastward, indicating a change in the catchment area, possibly coeval with the second phase of rifting. These were deposited in the hangingwall segments of the NW, N and NE fault systems, after the detachment of the Eocene plateau, and appear to have been controlled by the transverse ENE trending faults.
Humid and semi-arid to arid climatic changes were responsible for the upward changes in the fluvial sedimentation in the studied area.