Page:Africa by Élisée Reclus, Volume 2.djvu/144

 bank, a long rock continued by dunes, the basin, here called Shott Faraun, suddenly becomes three times larger, and forms the Shott-el-Jerid, or "the Shott of the Palms."

At its western extremity this huge lacustrine plain is culled by various other names. It is no less than 120 miles long from east to west, with a breadth, from north to south, at the widest part, of 45 miles. The riverain people say that water remains permanently only in the central part of the Shott-el-Jerid; but this water is not visible, being hidden by a saline crust, which suggested to the Arab authors its comparisons to a silver leaf, a crystal sheet, a bed of camphor. On it the footsteps re-echo as on the stones of an archway.

Besides the deep waters of the lake properly so called, which is concealed under its saline covering, the lowest parts of the lacustrine depression are usually filled

with water, at times of sufficient depth to reach the girths of horses crossing the sebkha, and which under the influence of the wind is displaced from side to side of the depression. When the water is driven on to the saline crust over the hidden springs, it becomes partially dissolved, and the level of the waters of the shott thus often becomes changed. It occasionally happens that the crust of salt is forced upwards by the pressure of the water, or of the inflated gases, into the shape of a cone, just as if a subaqueous volcano had sprung into existence. Thus are formed islands which, thanks to the mirage, when seen from afar appear like veritable hills, and, indeed, are so called by the riverain peoples.

One of the largest of these islands, called Jebel-el-Melah, or "Mountain of Salt," is scarcely twenty paces in diameter and rises no more than about 3 feet above