18 PROCEEBINaS OF THE GEOLOGICAL SOCIETr. [DcC. 9, 



tion, as I have not sufficient time at command to describe them in 

 the present paper. 



General Outline. — As regards its physical outline, the western side 

 of the peninsula of Arabia Petraea, or that part of it under immediate 

 consideration, between Suez on the north and Tur on the south, along 

 the coast of the Red Sea, together with the high ground behind, up 

 to the culminating point of the country on the ridge of Sinai, may be 

 best described as forming a series of comparatively level masses, ar- 

 ranged in steps or table-lands varying in height according to their 

 distance from the coast. Through these steps have been cut a number 

 of valleys, comparatively deep and of tortuous course, the general level 

 of the plains being broken by numerous peaks, formed either by out- 

 lying masses of sedimentary strata or the undenuded edges of dykes 

 of intrusive rocks, which have resisted the action of the atmosphere 

 more than the softer granite and crystalline schists containing them. 



Desert near Suez. — The country from Suez southward to the mouth 

 of "Wady Gharandel, a distance of 40 miles, as a rule, slopes gently 

 down to the sea, though in some places an old raised beach forms a 

 cliff from 10 to 25 feet in height. At Moses's Wells (Ain Mousa), 

 about seven miles below Suez, the beach is very flat, so that boats 

 cannot come within a considerable distance of the shore. The surface 

 of the ground is strewed with marine shells and corals, often cemented 

 into a kind of shelly oolite (miliolite). This recently formed rock is 

 common along both sides of the Gulf of Suez, and often contains full- 

 sized specimens of Tridacna gigantea with the nacre still fresh. At 

 Suez, just opposite the hotel at the landing-place for boats, on the 

 Arabian side, so much of it is fouiid that the excavations for the 

 Suez Canal are made by boring and blasting with gunpowder. 



Raised Beach. — Immediately on getting above the level of high- 

 water-mark, a change is seen in the shells, which are decidedly less 

 fresh in lustre and appearance, although not sensibly worn or broken, 

 and occurring in large quantities. The worn and broken appearance 

 becomes more marked on receding from the beach; and at the same 

 time the character of the sand changes. The proportion of fora- 

 miniferal shells and rolled grains of shell-sand diminish by the 

 admixture of grains of quartz and other comminuted rocks derived 

 from the waste of the interior cHff, until at about two miles from 

 the shore, and about 40 or 50 feet above high-water-mark, the 

 former have almost entirely disappeared. The subsoil at Moses's 

 Wells consists of soft shales and gypseous marls, which extend across 

 the bay to Suez. They are of marine origin, or at any rate have 

 been below water, as in a section on the Suez and Cairo Railway, 

 about half a mile from the town, they are seen to be covered by the 

 raised shell-beach before mentioned. 



Desert at Moses's Wells. — 'The general relation of the superficial de- 

 X)osits near the head of the Gulf of Suez is shown in PI. I. fig. 1 : « is 

 the escarpment of the Tertiary rocks, probably some part of the JNum- 

 mulitic series. Prom the foot of the cliif to c the ground is covered 

 with small table-topped hills and ridges, formed of a limestone- 

 gravel cemented into a conglomerate by means of gypsum, and about 



