All these were joined together in the vale of Siddim, which is the salt sea.
All these were joined together - i:e., were confederate.
The vale of Siddim, [Hebrew, `eemeq (H6010).] - a low and broad tract of land bounded by hills.
Siddim. Gesenius, who regards the word as probably Arabic, takes it to denote a depression or wady full of obstructions; a plain cut up by stony channels and pits (Genesis 14:10). [The Septuagint has epi teen pharanga teen halukeen , upon the salt valley. The common view is, that Sidiym (H7708) is the plural of saadeeh (H7704), a level cultivated field; and accordingly the Jewish Targums for the most part render "the vale of Siddim" 'the valley of the fields.']
Which is the salt sea. This clause is evidently designed to refer to that which precedes; and the unmistakable meaning of it is that what was formerly "the vale of Siddim" had in the days of the historian become "the salt sea." This is the name by which the Dead Sea is commonly designated in the Pentateuch and the Book of Joshua (Numbers 34:3; Deuteronomy 3:17; Joshua 3:16; Joshua 15:2; Joshua 15:5); and here there was a special propriety in the use of this descriptive epithet, from the contrast which that locality afterward presented to the sweet refreshing streams by which the vale had been formerly fertilized (Genesis 13:10).
It is pre-eminently entitled to be called "the salt sea," for it is impregnated with saline qualities far beyond other seas. 'The saline matter of the ocean occurs in pretty nearly the same proportion at whatever latitude the sample examined be taken. It amounts to nearly 35 percent, or in 100 lbs. of sea water 3 1/2 lbs. of saline matter, principally common salt. In this inland sea, however, which receives the waters of the Jordan and several other streams, but which has no outlet, the excess of water being carried off so rapidly by evaporation that the lake never overflows, the salts accumulate constantly. While the ocean shows the same 3 1/2 percent of salts ever since it began to be analyzed, here the quantity of salt accumulated is already so great (upwards of 20 percent, or 20 lbs. in every 100 lbs. of water) that the density of the water (l-24) in this sea is greater than any other, except perhaps in the great Salt Lake of Upper California. While the stated proportion of saline matter in the ocean is required by the plants and animals that inhabit it, the water in this sea is so intensely salt that no plant or animal can live in it: hence, it is sometimes known as the Dead Sea' (Phipson's 'Chemistry of the Sea').
It is peculiarly situated, being completely separated from, though so near to, the Mediterranean by a high chain of mountains; and English science, in the course of Palestinian Explorations, has very recently ascertained the exact geodesical position of this sea. Captain Wilson, of the Royal Engineers, after a most carefully conducted survey, has proved that, on the 12th of March last, the Dead Sea lay 1,292 feet below the level of the Mediterranean. This is an unexampled depression of surface: it is by far the deepest known fissure on the earth's surface.
Finally, the salt in the ocean is supplied by rivers which, in their passage, dissolve every soluble ingredient they meet with, and carry it to the sea; moreover, the sea itself corrodes the various coasts, and dissolves saline matter daily. But the saltness of "the Salt Sea" is caused not only by the conveyance to it, by the Jordan, of earths containing rich saliferous deposits, but by the proximity of rock-salt-the Mountain of Salt-Jebel Usdum.
Now, as to the relation of the cities of the Pentapolis to the vale of Siddim, a great difference of opinion exists. Without stopping to examine the sites fixed upon by M. de Saulcey for Sodom at Usdum, at the southwestern, and for Gomorrah at Goumram, at the northwestern extremity of the lake, which, though alleged discoveries, are purely imaginary, there are two theories respecting the position of the five towns. The one, rejecting the words "which is the salt sea," as the interpolated gloss of some late and uninspired editor, places all the cities on the north of the lake, which is considered to have existed from the earliest ages as it is now; appeals in support of this view to Genesis 10:19, where the cities are described as extending in a row from west to east; also to Genesis 13:10, where Abram and Lot are represented standing upon an eminence, whence they could see "all the plain of Jordan" - i:e., all the tract to the north of the lake, but not any further south; and assigns the locale of Siddim somewhere in the same northern quarter, on the ground that the five kings would not have chosen Siddim for their battle-field had it been to the southward, as in marching to it they would have had to pass the enemies' camp in Hazezon-tamar (Genesis 14:7). The other theory, considering the clause "which is the salt sea," to be genuine Scripture-as integral a part of the composition of Moses as any other portion of the history, regards, consequently, "the vale of Siddim" to have been in the spot now occupied by the southern half of the lake (cf. Joshua 12:3; also Josephus, 'Antiquities,' 1: 9), and recognizes the ruins of Zoar in the mounds of rubbish that are found at the southeast angle of the Dead Sea, at the mouth of Wady Kerak, near the promontory Lisƒn. This is the view of Robinson, Stanley, Porter, etc. (see further the note at Genesis 19:28).