[Footnote 119: This is in latitude 27° 35′ N., and therefore outside the limits of the region specially described in this memoir, but is quoted as a useful example.] [Footnote 120: Pronounced to rhyme with the English word _shalt_.] [Footnote 121: The map of the roads and water sources on Plate III, p. 26, should be referred to in connexion with this list.] PLATE XX. [Illustration: GEOLOGICAL MAP OF SOUTH-EASTERN EGYPT. Ball. Geography & Geology of South-Eastern Egypt. Photo-Metal-Process. Survey Dept. Cairo 1910. (60-190)] CHAPTER VIII. * * * * * =GEOLOGY.—SEDIMENTARY ROCKS.= * * * * * Only a small proportion of South-Eastern Egypt is covered by sedimentary rocks. As will be seen from a glance at the geological map on Plate XX, sedimentary strata are to be found only in the north-western and central portions of the area, where the Nubian sandstone which covers so much of the country close east of the Nile terminates in a long south-easterly projection, and along certain portions of the coast, where small outliers of Nubian sandstone and patches and strips of gypseous limestones and coral reef occur. The oldest rocks of undoubted sedimentary origin, the Nubian sandstones, are of Cretaceous age. Tertiary beds are absent, except for the gypseous strata of Ras Benas, which may possibly be Miocene. Quaternary deposits are represented by Pleistocene and Recent coral reefs and beach deposits, and by accumulations of alluvial downwash, blown sand, and calcareous tufa. The sedimentary deposits may thus be classified into:— (1) _Recent Deposits_ (coral reefs and raised beaches, blown sand, alluvial deposits, and calcareous tufa). (2) _Gypsum and Gypseous Limestones_ (of uncertain age, possibly Miocene). (3) _Nubian Sandstone_ (Cretaceous). =Coral Reefs and Raised Beaches.=