With reference to such analogies, the character and the physical constitution of the gorge in which the Dead Sea lies, has excited great interest in every age. The valley has been generally considered as of volcanic formation, though it is somewhat doubtful how far it is strictly correct thus to characterize it, since no signs of lava or of extinct craters appear in any part of it. The whole region, however, is subject to earthquakes, and many substances that are usually considered as volcanic productions are found here and there along the valley, especially near the southern extremity of the Dead Sea. One of the most remarkable of these substances is bitumen, a hard and inflammable mineral which has been found, from time to time, in all ages, on the shores of the sea. Some writers have supposed that the "pits," which are referred to in the passage, "And the vale of Siddim was full of slime pits," were pits of liquified bitumen or asphaltum,--that the plain of Sodom was composed in a great degree of these and similar inflammable substances--that they were set on fire by lightning from heaven or by volcanic ignition from below, and that thus the plain itself on which the cities stood was consumed and destroyed. Others suppose that under the influence of some great volcanic convulsion, attended, as such convulsions often are, by thunderings and lightnings--the brimstone and fire out of heaven, referred to in the sacred record--a sinking, or subsidence of the land at the bottom of the valley, took place; and that the waters of the Jordan overflowed and filled the cavity, thus forming, or else greatly enlarging the Dead Sea. That the waters of the sea now flow where formerly a tract of fertile land extended, seems to be implied in the passage, Gen. xiv. 3, in which it is stated that certain kings assembled their forces, "in the vale of Siddim which is the Salt Sea." The meaning is undoubtedly as if the writer had said, The armies were gathered at a place which was then the vale of Siddim, but which is now the Salt Sea. THE DEAD SEA IN THE MIDDLE AGES.