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Secretary of the Geological Society, I am able to illustrate this chapter with a geological map based chiefly on the maps of Lartet, Hull, and Zittel. To a great extent it tells its own story regarding the features of the country, and the rocks and formations of which the region is constructed. The oldest rocks occupy the greater portion of the Sinaitic peninsula, as well as the mountains bordering the Gulf of Akabah, and extending northward along the eastern side of the Wady el Arabah. They consist of granitic, gneissose and schistose rocks, amongst which have been intruded great masses of red porphyry, dark green-stone, and other igneous rocks in the form of dykes, veins, and bosses. These rocks are probably among the oldest in the world. After these ancient rocks had been consolidated they were subjected to a vast amount of erosion, and were worn into very uneven surfaces, over which the more recent formations were spread; first filling up the hollows with the lower strata, and ultimately covering even the higher elevations as the process of deposition of strata went on. The oldest of these formations is the Red Sandstone and Conglomerate, which Professor Edward Hull calls the "Desert Sandstone" formation. It forms a narrow strip along the margin of the old crystalline rocks. It is capped with the fossiliferous limestone of the Wady Nash, which shows it to belong to the Carboniferous period—in fact to be the representative of the Carboniferous Limestone of Europe and the British Isles. It is also found east of the Arabah Valley and amongst the mountains of Moab east of the Ghor. This is succeeded by another Sandstone formation, more extensively distributed than the former. It belongs to a much more recent geological period, namely, the Cretaceous; and is the representative of the "Nubian Sandstone" of Roziere, so largely developed in Africa, especially in Nubia and Upper Egypt This is succeeded by the Cretaceous and Nummulitic