The clay minerals identified in both sandstones and mudstones
are illite and kaolinite. The proportions of illite to kaolinite vary
antipathetically (Fig. 2) from an illite dominated lower section to
a kaolinite dominate upper section. These variations may be related to relative changes in the climatic conditions in the source
area. The moderate crystallinity exhibited by the clay minerals
indicates their detrital origin from weathering horizons and soils
developed on silicic rocks, and transportation in a fluvial environment (Keller, 1956; Abu-Zeid et al., 1989, 1991).