The great salt lake is a deep extensive basin, separated by an immense lava stream from the remainder of the bay, the head of which it once formed. Resembling the Dead Sea in the depression of its level, in the density and chemical constitution of the fluid, and in the loneliness, sterility, and desolation of its borders, it yet differs from it materially in the ways by which volcanic action has produced the strange phenomenon of the existence of shores so considerably below the level of the ocean. In the Dead Sea, the lake of Tiberias, and the valley of the Jordan between them, it has apparently been a distortion and crushing of immense masses which have subsided into subterranean caverns. In the Bahr Assai it has been produced by the erection of a new bank, serving as a dam or barrier across the head of a long narrow bay, by which a considerable body of sea-water was separated from the former common receptacle. As high as the level of the Arabian Gulf are to be found, in the basin of Bahr Assai, the salts and earthy (magnesian) precipitates of the salt water, which in the course of time was reduced to its present level by evaporation, the yearly supply of rain-water being but as a drop to the ocean. Huge heaps of lava, having been apparently in strife with the opposite element, are erected on the banks over wacke, or in other cases over a finely-grained soft mart. The latter, when clear of lava, presents a thin layer of gypsum, with numerous shells of Melania, Limnaeus, Physa, Planorbis, Cyclostoma, Unio, and Cycas, some of which are at present to be found in the distant fresh-water pools and rivulets. The shallow water on the borders of the lake presents natural salt-pans, and a crust of fine salt, two inches thick and tolerably clean, covers nearly the whole of the surface. The supply would seem to be inexhaustible; for when cut out with a spaddle, a new crust is soon furnished from the waters beneath. Being visited by almost every tribe of the Adaiel and Somauli, and unhappily situated on the borders of the most lawless and savage of them, this remarkable spot is almost forbidden ground for the observer, not to speak of the obstacles thrown in the way by the destructive temperature and the general absence of the necessaries of life. In the ravine of Goongoonteh, and during the continuation of the journey as far as Killulloo, slight variations of trap formation were met with. The wacke is of a fine grain, and its constituents are indistinctly mingled; it is traversed by empty holes and bubbles, and occasionally by druses of zeolith. Coarse quartz, sandstone, and conglomerates are sometimes found towards the surface. The country must have frequently been agitated by violent earthquakes, detaching huge masses of rocks from the hills; and, bereft alike of vegetation and animal life, it presents altogether a most monotonous appearance.