Dead Sea (Lat. Lacus Asphaltites; Arab. Bohr Lut, sea of Lot; also called the sea of Sodom, and in the Scriptures the salt sea, sea of the plain, and eastern sea), a. salt lake of Palestine, between the mountains of Moab on the east and those of Hebron on the west, about 18 m. E. of Jerusalem, 42 m. long from N. to S., and nearly 10 m. in greatest breadth. The locality is that of the ancient vale of Siddim, which Lot selected when he parted from Abraham, and which was then an attractive region, watered by the Jordan, and containing the cities of Sodom and Gomorrah. Even at that early period the district was probably of peculiar geological character, the vale being described as "full of slime pits" (Gen. xiv. 10). The catastrophe which resulted in the destruction of these cities, and in the formation of the sea, is computed to have occurred about 1900 years before the Christian era. By earthquake, accompanying volcanic action (Gen. xix. 28), the valley appears to have sunk to a great depth, and the waters of the Jordan flowing in produced this sea, which was made intensely salt by the saline strata exposed to their action.

On its S. W. side is a mountain retaining the name of Sodom (Usdum), containing strata of salt, out from which stands a lofty pillar of the same material, observed by Lieut. Lynch of the United States navy, which is probably what travellers often describe by the name of Lot's wife. It is about 40 ft. high, standing upon an oval pedestal, the top of which is 40 or 50 ft. above the water. The pillar is capped with limestone. Josephus speaks of a similar pillar, perhaps the same, which he himself saw, and believed to be that into which Lot's wife was transformed. Clement of Rome and Irenseus also mention it. Bitumen or asphaltum, from which the sea receives one of its names, is found along the shores of the lake, and during some recent earthquakes, to which the region is still subject, it was thrown up in large quantities at the 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 water. He supposes the pillar described by Lynch to be one of these.

Mr. Tristram, in his descriptions of the southern parts, says that sulphur springs are frequent on the shore; sulphur 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 deposited with gravel on the beach, or appears to have been precipitated during some convulsion. 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 bottom; and when brought up in sounding, crystals of salt are found sticking to it. But a portion of the bottom is rough and rocky, and subject to sudden and great changes of depth. This feature, in connection with the pieces of lava occasionally found, seems to indicate a formation 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 Jordan valley itself. Other eruptions of less importance took 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 engineers, which was confirmed by nearly identical results afterward obtained by the same method by Lieut. Lynch, the difference of level of the two surfaces is 1,312.2 ft.

This depression 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, especially 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 evaporation, which toward the afternoon generally renders the air heavy and dark, and the surrounding 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 mountains 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°. Currents 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 object 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 rapidly 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 bituminous stone, susceptible of a high polish, which is employed by the natives in mosaic pavements 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 southeast, beyond the marshes, are sandstone mountains, a continuation of the Edom range, which give place to limestone in the valley of Kerak, but appear again below the limestone mountains 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 quantities 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 seamen belonging to the American expedition were sent to the convent of Mar Saba for relief, and Lieut. Dale, the second officer, before the party left the country, fell a victim to the fever at Beyrout, where Lieut. Lynch also and nearly all his men were attacked by the same disease. In March, 1848, the latter party, despatched by the United States government, and well equipped, passed across, with their boats drawn on trucks by camels, from the bay of Acre, over the mountains of Lebanon, and launched them in the lake of Gennesaret. Thence they descended the Jordan, entering the river on April 10, and passing out of its mouth into the Dead sea on the 19th of the same month.

They spent 21 nights on the shores of the Dead sea, and after having thoroughly explored the region, they left it on May 10, sending their boats across the desert to Jerusalem. Contrary to the opinion generally entertained regarding the pestilential atmosphere of,this neighborhood, they found numerous animals living upon the shores of the lake, as doves, hawks, partridges, and hares, and also ducks swimming upon its surface; and a curious fact regarding the birds, insects, and other animals here met with, is that they are all of a stone color, described as "the same as the mountains and the shore." In the sample of water brought back by the party no vestige of animal life was detected; but in Jameson's "Philosophical Journal" of February, 1850, it is stated that Ehrenberg found an abundance of infusoria of brackish.water species in samples of the water and sediment brought to him for examination. The want of vegetable matter for food must necessarily to a great extent exclude animal life. A few plants which furnish soda in their ashes are occasionally found on the shore, and at the foot of the cliffs is noticed a scanty vegetation of cane and of the tamarisk shrub, their foliage sometimes of a light green and sometimes of a yellow hue, stained by the exhalations of sulphuretted hydrogen; but the few bushes to be seen often present their branches leafless and incrusted with salt; and the trunks of dead trees scattered here and there add to the desolation of the scene. - De Saulcy came to the conclusion that the sites of Sodom and Gomorrah are to be sought for on the W. shore, and that those cities were not submerged, as is generally supposed.

He found extensive ruins on the N. side of the mountain of Usdum, and a mile and a half to the northwest other ruins, which last he believed to be those of Zoar. - Various analyses have been made by eminent chemists of the water taken from the lake, the results of which differ, in consequence no doubt of the different seasons of the year and portions of the lake at which the samples were taken, and also of the different methods of conducting the analyses. The specific gravity, as stated by Lavoisier and Klaproth, is 1.24; by Marcet, 1.211; by Gmelin, 1.212; by Apjohn, 1.153; by Salisbury, 1.1877; and by Lynch, 1.13. The constituents are thus given by different authorities:

Table I

SUBSTANCES.

Pogg. Ann.

Booth and

Muckle, depth

1,110 ft.

Genth, 1858.

Chloride of potassium...

1.398

0.659.

1.0087

" sodium.....

6..578

7.855

7.5839

" calcium....

2.894

3.108

2.8988

" magnesium..

10.543

14.590

10.1636

Brom. potasa'm

Bromide of magnesium..

0.251

0.137

05341

Sulphate of lime.....

0.088

0.070

0.0901

Carbonate of lime....

....

....

0.0042

Hydrated sesquioxide of iron....

....

....

0.0087

Silicic acid....

0.003

0.0113

Nitrogenous organic mat.

....

....

0.0052

Solid parts in 100....

21.773

26.419

22.3086

Table II

SUBSTANCES.

Marcet.

Klaproth,

Muriate of lime......

8.920

10.60

" magnesia.....

10.246

24.20

" soda....

10.360

7.80

Sulphate of lime.........

0054

....

24.530

42.60

Water...........

75.420

57.40

100.000

100.00

The first of the above analyses, from Poggen. dorff's Annalen, is of a sample of the water procured from the north end of the sea, near the mouth of the Jordan.