Page:Mount Seir, Sinai and Western Palestine.djvu/198

162 the principal terrace which borders the southern margin of The Ghôr, to which Jebel Usdum belongs. According to Tristram, the surface of the lower plain is formed of mud and silt, containing fresh-water shells of the Jordan and its tributary streams, of which Melanopsis prœrosa and M. Saulcyi occur in this locality; and lead him to the conclusion, that within a comparatively recent geological period, the whole lower valley has been exposed to fresh-water floods from the upper Jordan, where these shells abound. When crossing the Cherith Valley, on our way to the banks of the Jordan on the following day, we searched the marly and gravelly banks for remains of shells, but without success; we were then about 275 feet above the surface of the Salt Sea.

At about a mile from the banks of the Jordan, we descended about 40 feet on to a lower terrace, a little over 200 feet above the same datum. The materials are of white marl, encrusted with saline matter, and they break off in a succession of little plateaux with symmetrical banks, descending to the alluvial plain which borders the river, and which sustains a dense growth of trees, shrubs, and reeds—the haunts of the wild boar. Altogether, between the escarpment of Jebel Karantul, which bounds the valley of the Jordan on the west, there are three well-marked terraces, which have successively formed the bed of the ancient inland sea, namely :—

All these terraces, except perhaps the upper, have doubly sloping surfaces, both towards the centre of the valley, and towards the Salt Sea, so that the levels taken along one line would not correspond exactly with those taken along another. The upper terrace only slopes towards the centre of the valley, as its upper surface corresponds almost exactly with the terrace of Jebel Usdum, and the other old sea margins, near the southern end of The Ghôr.