From Jebel Horabi, at the extreme north end of the depression, the western wall, or escarpment, trends in a general direction of 30° south of west for about 20 kilometres before it turns and runs some 5 kilometres south, forming the prominent headland about 2½ kilometres north-west of El Qasr. This cliff, probably the boldest part of the whole oasis-wall, attains a height of some 175 metres above the lowest part of the floor of the depression. It is steep throughout and the only practicable passes to the plateau above are through occasional gullies, in which the slopes are of easier gradient. The main caravan road from El Qasr and Bawitti to Mogara and Alexandria gains the plateau by the long narrow gully 6½ kilometres N.N.W. of El Qasr. To the south of the headland, 2½ kilometres north-west of El Qasr, the escarpment runs back and forms a remarkable narrow bay, running east and west, with an average width of only 4 kilometres, and extending some 18 kilometres west of El Qasr. This indentation is separated from a much larger opening to the south by a long narrow promontory, or tongue of plateau, barely a kilometre wide in places. The extreme point of this tongue is 9 kilometres south-west of Bawitti. The large bay to the south is bounded on the north by the usual steep wall of rock, but this becomes much less prominent at the western extremity, where the escarpment is low and easily accessible to camels. A few kilometres out to the west is another escarpment of white chalk trending irregularly in a N.N.E. and S.S.W. direction. An old road, probably joining the main caravan road from Bawitti to Siwa further west, runs up this bay and on to the plateau beyond. Numerous large and small hills occur within the bay. The southern cliff, formed of dark brown or black ferruginous sandstones, is remarkably irregular, and quite different in appearance and weathering from the northern wall. The promontory to the south of this bay juts out boldly into the oasis-area. Further south the escarpment recedes and runs in the most irregular manner some 25 kilometres south-west, several times retreating to form well-marked indentations in the general line of cliff; it afterwards trends 15 kilometres south-east up to the prominent corner 4 kilometres west of Ain el Haiss. A road from Ain el Haiss to Siwa reaches the escarpment 15 kilometres north-west of the spring, passing up a gully of easy gradient to the plateau. About 7 kilometres further on the chalk escarpment, already mentioned, is seen running N.N.E. and S.S.W.