vertical joint planes, there have been large dislodgments of the sides of the clitf, supposed to have been due to an earthquake; while the rock-salt uusupported by the firmer sides, has been bent along the faces of the joints by the superincumbent weight of materials. This remarkable phenomenon is represented in the adjoining sketch. Fig. 17.
The lower part of Jebel Usdum is formed of solid bluish rock-salt, which reaches a thickness from 30 to 50 feet, and this is capped by beds of marl, salt, and gypsum ; while below the rock-salt are beds of gravel, shale, and laminated sandstone, often crushed out and lying in heaps at the base of the cliffs. There was no doubt in the mind of myself, or of any of our party, that this salt mountain is a portion of the ancient bed of the Salt Sea, and the elevation of its upper surface, 600 feet above the waters of the sea itself, confirms this view.[1]
Mr. Hart furnishes the following account of the upper surface of this hill:—
"On Thursday, the 27th of December, when passing under the eastern base of Jebel Usdum, en route from Es Safieh to Gaza, it occurred to me that the salt cliffs of that unique eminence did not look by any means so inaccessible as writers had led me to suppose. Choosing a point about half-way in its length on the steep eastern face, I scrambled up the rock-salt and white powdery marls which partly covered it for about 200 feet;—my friend, Mr. Reginald Laurence, following me; after that there was no further difficulty. The solid mineral salt appeared to cease at about 100 or 150 feet, and the remainder of the elevation was a cap of marl. The salt is cut and broken into all sorts of glacier-like crevasses and ugly black holes visible for another hundred feet or so. A slip down one of these treacherous caverns, where ice is replaced by glittering salt, and snow by white marl, would produce a well-preserved museum specimen for future naturalists. The marl is here scooped out by water action into blocks and beds and mounds of dust, often half concealing the pits. After a while the cracks are filled (at least as I passed over them I hoped so), and in about a mile I reached the base of the inner ridge, the highest point of which my aneroid gave me at 600 feet above the Dead Sea. In
- ↑ M. Louis Lartet states the thickness of the rock salt to be 20 metres, aud Hut the summit is formed of chalky limestone with bands of flint, belonging to the Cretaceo-nummulitic formation. In this view I am unable to concur; and possibly, if M. Lartet had been able to examine the summit himself, he would have arrived at a different conclusion.
