9. Moghra Formation consists of a thick (203m) clastic section of variegated shales, thin marls, sands and calcareous grits with large quantities of silicified trees and few scattered fluviomarine fossils. It is particularly developed to the south of a line that runs from Siwa to Wadi El Natrun and forms a conspicuous part of the northern Qattara wall. Marmarica Limestone covers the Marmarican Plateau to the north of Siwa - Wadi El Natrun line. It is very uniform in character and practically horizontal. It is made of a solid limestone (78 m thick) that becomes a little sandy towards the east. It is rich in shallow marine Langhian fossils as Scutella zitteli, Echinolampus amplus, Ostrea digitalina, etc...

16. Economic mineral deposits: In addition to the importance of the Miocene sediments as being the main Oil-producting horizon in the Gulf of Suez, some of the Miocene mineral deposits are of economic importance: Gypsum is quarried from the Middle and Upper Miocene at Ras Malaab, southwestern Sinai. Also, lead, zinc and sulphur as metasomatic replacement hydrothermal deposits of some Miocene sediments occur along the Red Sea coast.

17. The Quaternary sediments in Egypt have been subdivided by BALL (1939) into: - Raised beaches and coral reefs along the Red Sea coast, - Oolitic limestones on the Mediterranean coast. - Alluvial deposits in the Nile Valley and the Delta, - Lacustrine deposits and the Nile mud in Fayoum Depression, - Alluvial deposits in the drainage channels and depressions, - Calcareous tufa in the oases of Kharga and Kurkur, and - Dunes and other wind-borne sand accumulations.

19. The geological evolution of the River Nile in Egypt Under this title SAID (1981 & 1990) has summed up what is known at present about the development of the Nile system in Egypt. Sediments form one of the chief sources of information; they show great changes in the river valley since its "down cutting" through earlier rocks in the Late Miocene. Five river phases succeeded each other: the Eonile in the Late Miocene, Paleonile in Late Pliocene, and the Proto-, Pre- and NeoNile in the Pleistocene. These phases were separated by "episodes", with the river declining or even ceasing its flow for reasons of tectonic and climatic changes