Soils Derived From Shale Deposits In Egypt. I. Soil Genesis and Classification.
Gamil W. Ageeb, National Research Center, El Bohus St., Dokki, Cairo, 11211, Egypt
The investigation deals with shale deposits, cover a considerable area in Egypt, in order to clarify their genesis and classification. The area of the surface outcrops of these shales are about Го41484 km2 (Го4 % of total area of Egypt). Twenty-four soil profiles representing nine types of the most dominant shale deposits in Egypt, named: Qasr El Sagha, Wadi Rayan, Maadi, Mokattam groups (Maghagha, Qarara, Beni Suef Formations), Dakhla, Quseir, Esna, Wadi Abbad and Lower Esna Formations( pale grey and dark grey shale members). The profiles are chemically, physically, micromorphologically and mineralogically studied. The data showed that these soils are deep to very deep, clayey textured (mostly fine clay), salt-free to extremely affected by salts, natural to midly alkaline and have high content of both calcium carbonate and gypsum. Ten subgreat groups were identified. They are Typic Haplotorrerts, Typic Salitorrerts, Typic Haplosalids, Typic Haplocalcids and Typic Calcigypsids, Entic Haplotorrerts and Entic Salitorrerts, Calcic Haplosalids, Gypsic Haplosalids and Petrocalcic Haplosalids (Soil Survey Staff, 1998). Applying the grain size parameters suggests that the shale derived soils are mostly transported and deposited by water or weathered in situ under an aqueous environments. Micromorphological studies showed a state of stratification due to existence of more than one parent material or to multidepositional regimes. Considering the genesis and formation of these shale derived soils, they are mostly geogenesis and it is geological formation. The effect of geological age overshadows the other soil factors. The clay mineral compositions of these shale derived soils are widely varying according to mode of origin, shale type and geological age.