Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/99

 mass, but an old lava-flow which was poured out in shallow water during the formation of the flint-conglomerate. The general section at this place is shown in Pl. I. fig. 3. The outer horizontally arranged beds, consisting of the rubbish and detritus of the hills, form a roughly terraced cliff above the plain of the Marcha, which latter is most likely formed of sand and gypseous marl, like those of Suez and of Moses's Wells.

Sarabut e Gamnal — Flint-conglomerate. — In the higher parts of Wady Atal, Gharandel, and the other valleys cut through the table- land of the white limestone, the sections are much obscured by the accumulation of alluvial gravels, which increase in quantity towards the interior of the country ; and as the valleys are broad, with comparatively low cliffs, drifted sand also accumulates in considerable quantities in places. On reaching the high ridge known as Sarabut e Gamnal, which covers the pass leading into the sandy plain of Ramleh, there is a great change in the character of the beds — an enormous quantity of coarse flint-conglomerate and white limestone forming the crest of the hill on either side. These, no doubt, belong to the same set of beds as the rocks at the mouth of Wady Gharandel and Wady Taibe, although developed on a greater scale : and, judging from the size of the pebbles, they have probably been deposited in shallower water than the same beds further westward. A fault with a westerly downthrow crosses the ridge of Sarabut e Gamnal, throwing the flint-conglomerate against the dark-red or brown Triassic sandstones below. This dislocation, either alone or with a system of parallel fractures, is continuous for many miles in a north and south line, and has a marked effect on the physical geography of the country ; for by it the soft white and bituminous series of beds in the region already described are cut off, as by a wall, from the older rocks of the interior.

Ramleh (see Pl. I. fig. 4). — The plain of Ramleh, about 1750 feet above the sea-level in the centre, and about ten or twelve miles broad from north to south, is covered with drifted and blown sand, resting on red and brown quartzose sandstones and conglomerates, the beds being nearly flat, or forming a slight anticlinal arch. On the northern side it is bounded by the great escarpment known as Jebel el Tih, which forms the edge of the Cretaceous and Tertiary plateau extending northward to El Arish and Palestine. The southern edge is deeply indented with many narrow and winding valleys, which are cut down to the crystalline rocks below, and which unite with like valleys coming from the south, from the main- drainage line of the district in Wady Baba.

Tih Escarpment. — As regards the escarpment of Tih I have but little information to give, as it lies beyond the district where I was more immediately at work. For the following section I am indebted to my friend and associate Dr. C. Le Neve Foster, who made a flying visit from our camp in Wady Suoug : —