726 DEAD SEA southern extremity of the sea. De Saulcy in 1851 saw huge masses of salt which had been detached by the winter rains and rolled down the mountains, some of them lying in the wa- ter. He supposes the pillar described by Lynch to be one of these. Mr. Tristram, in his de- scriptions of the southern parts, says that sul- phur springs are frequent on the shore ; sul- phur is strewn in layers or in fragments over the plains; and bitumen is ejected in great floating masses from the bottom of the sea, oozes through the fissures of the rocks, is de- posited with gravel on the beach, or appears to have been precipitated during some convul- sion. From its abundance in this region it is often called Jews' pitch. The banks N. and S. are slippery, with a slimy mud, into which the foot sinks deep, and the tracks thus left are soon lined with incrustations of salt. A similar mud covers a considerable portion of the bot- tom; and when brought up in sounding, crys- tals of salt are found sticking to it. But a por- tion of the bottom is.rough and rocky, and sub- ject to sudden and great changes of depth. This feature, in connection with the pieces of lava occasionally found, seems to indicate a for- mation due to volcanic agency. M. Lartet found that deposits of great depth have accumulated in this valley since its formation ; they consist of numerous thin beds of gypsum, marl, flint, and alluvium. These layers, which cover the whole valley, are analogous to those now in process of formation at the bottom of the Dead sea. He saw evidences of volcanic action of a date long posterior to the formation of the valley, and concluded that eruptions have taken place at the N. E. end of the basin, which produced important flows of basalt, some of them extending as far as the Jor- dan valley itself. Other eruptions of less im- portance toojs place directly E. of the lake, of which three reached the eastern shore. The water is dense and bitter with its heavy charge of salt, so that bodies float in it with much greater buoyancy than in other seas. In bathing, one experiences difficulty in keeping the feet down, and a man may float in it breast high without exertion. On anything being dipped into the sea and withdrawn, the water almost immediately evaporates, leaving a thin crust of salt. The southern part of the lake has an average depth of only 13 ft. ; but the northern portion, as sounded by Lieut. Lynch and others, is found to reach a maximum depth of more than 1,300 ft. A remarkable feature in the lake is its great depression below the level of the Mediterranean. By the levelling conducted by Lieut. Symonds of the royal en- gineers, which was confirmed by nearly iden- tical results afterward obtained by the same method by Lieut. Lynch, the difference of level of the two surfaces is 1,312'2 ft. This depres- sion is the deepest of the kind known on the earth. The swift current of the Jordan, often rushing on in rapids dangerous to navigate, even with the iron boats of the expedition under Lieut. Lynch, pours a large volume of water into the deep basin, from which there is no outlet. During the rainy season the level of the sea is raised 10 or 15 ft., and it extends, es- pecially in a southern direction, over the low flats, several miles beyond the ordinary margin of the waters. But in the dry season, when the beach becomes so hot as to blister the feet, and the water acquires a temperature of 90 F. a foot below the surface, evaporation rapidly carries off the excess of water, and reduces the sea to its lowest level. The immense evapora- tion, which toward the afternoon generally renders the air heavy and dark, and the sur- rounding marshes, give rise to agues, so that the inhabitants of the vicinity are sickly. At this season the air becomes so highly heated in the deep basin between the precipitous moun- tains which enclose it, that it is almost irre- spirable, and the thermometer often rises to 106 or more, even after the setting of the sun. At midnight it was observed to be 98. Cur- rents of this heated air sweep in hurricanes over the water. As described by the United States officers, the hot wind blistered the faces of the men exposed to it. Every metallic ob- ject was burning hot; the coolest substances were the inner surfaces of the clothing. If a pool of fresh water were found to bathe in, the skin was instantly afterward left dry and parched. The perspiration evaporated as rap- idly as it was produced. The hills on each side are precipitous cliffs of limestone and sandstone in horizontal strata. On the east they are rugged mountains 2,000 to 2,500 ft. high, traversed by deep chasms, desolate and bare of vegetation. On the west the height is estimated at 1,500 ft.; but the summit level upon the whole is little if any higher than the surface of the Mediterranean. The whole range along the western shore is limestone, similar to that in the neighboring hills. On the shore and hills are also found large blocks and rocks of a black and inflammable bitumi- nous stone, susceptible of a high polish, which is employed by the natives in mosaic pave- ments and in making trinkets for pilgrims. On the southwest are the remarkable salt hills of Usdum, which are the principal source of the extreme saltness of the water. On the south- east, beyond the marshes, are sandstone moun- tains, a continuation of the Edom range, which give place to limestone in the valley of Kerak, but appear again below the limestone moun- tains of Moab. The peninsula El-Lisan is a post-tertiary deposit of carbonate of lime and sandstone, disintegrated and intermixed with sulphur. On the N. E. angle are large quan- tities of post-tertiary lava, pumice stone, and various kinds of volcanic slag. Mr. Costigan, who surveyed the sea in 1835, with a Maltese sailor as his servant, died soon after completing its tour. Lieut. Molyneux of the royal navy met the same fate in 1847. Two of the sea- men belonging to the American expedition were sent to the convent of Mar Saba for relief,
