The geological formation of Syria is highly favorable to the production of caves. It consists chiefly of limestone, in different degrees of density, and abounds with subterranean rivulets. The springs issuing from limestone generally contain carbonate of lime, and most of them yield a large quantity of free carbonic acid upon exposure to the air. To the erosive effect upon limestone rocks, of water charged with this acid, the formation of caves is chiefly to be ascribed. The subordinate strata of Syria, sandstone, chalk, basalt, natron, etc. favor the formation of caves. Consequently the whole region abounds with subterranean hollows of different dimensions. Some of them are of immense extent, such as those noticed by Strabo, who speaks of a cavern near Damascus capable of holding 4000 men. The first mention of a cave in Scripture relates to that into which Lot and his two daughters retired from Zoar, after the destruction of Sodom and Gomorrah (). The next is the Cavesof Machpelah, in the field of Ephron, which Abraham purchased of the sons of Heth (; ). There Abraham buried Sarah, and was himself afterwards buried; there also Isaac, Rebecca, Leah, and Jacob, were buried (; ). The cave of Machpelah is said to be under a Muhammadan mosque, surrounded by a high wall called the Haram; but even the Muslims are not allowed to descend into the cavern. The tradition that this is the burial-place of the patriarchs is supported by an immense array of evidence.
The situation of the Cave at Makkedah, into which the five kings of the Amorites retired upon their defeat by Joshua, and into which their carcasses were ultimately cast, is not known (; ). Some of the caves mentioned in the Scriptures were artificial, or consisted of natural fissures enlarged or modified for the purposes intended. It is recorded () that 'because of the Midianites, the children of Israel made them the dens which are in the mountains, and caves, and strongholds.' Caves made by art are met with in various quarters. An innumerable multitude of excavations are found in the rocks and valleys round Wady Musa, which were probably formed at first as sepulchers, but afterwards inhabited, like the tombs of Thebes. Caves were used as dwelling-places by the early inhabitants of Syria. The Horites, the ancient inhabitants of Idumea Proper, were Troglodytes or dwellers in caves, as their name imports. Jerome records that in his time Idumea was full of habitations in caves, the inhabitants using subterranean dwellings on account of the great heat. The Scriptures abound with references to habitations in rocks; among others, see ; ; ; . Even at the present time many persons live in caves. Caves afford excellent refuge in the time of war. Thus the Israelites () are said to have hid themselves in caves, and in thickets, and in rocks, and in high places, and in pits. See also . Hence, then, to 'enter into the rock, to go into the holes of the rocks, and into the caves of the earth' (), would, to the Israelites, be a very proper and familiar way to express terror and consternation. The pits spoken of seem to have consisted of large wells, in 'the sides' of which excavations were made, leading into various chambers. Such pits were sometimes used as prisons (; ; ); and with niches in the sides, for burying-places (). Many of these vaulted pits remain to this day. The strongholds of Engedi, which afforded a retreat to David and his followers (; ), can be clearly identified. They are now called Ain Tidy by the Arabs, which means the same as the Hebrew, namely, 'The Fountain of the Kid.' 'On all sides the country is full of caverns, which might serve as lurking-places for David and his men, as they do for outlaws at the present day. The whole scene is drawn to the life.' The Cave of Adullam, to which David retired to avoid the persecutions of Saul (), and in which he cut off the skirt of Saul's robe (), is an immense natural cavern at the Wady Khureitun, which passes below the Frank mountain. Such is the extent of the cavern, that it is quite conceivable how David and his men might 'remain in the sides of the cave,' and not be noticed by Saul (Travels, vol. ii. p. 41). Caverns were also frequently fortified and occupied by soldiers. Josephus relates also that Herod sent horsemen and footmen to destroy the robbers that dwelt in caves, and did much mischief in the country. They were very near to a village called Arbela (now called Kulat Ibn Ma'an). The occupants were not subdued without great difficulty. Herod then laid siege to certain other caverns containing robbers, but found operations against them very difficult. These were situated on the middle of abrupt and precipitous mountains, and could not be come at from any side, since they had only some winding pathways, very narrow, by which they got up to them. The rock that lay on their front overhung valleys of immense depth, and of an almost perpendicular declivity. To meet these difficulties Herod caused large boxes filled with armed men to be lowered from the top of the mountain. These men had long hooks in their hands with which they might pull out those who resisted them, and tumble them down the mountains. From these boxes they at length slipped into the caverns, destroyed the robbers, and set fire to their goods. Certain caves were afterwards fortified by Josephus himself during his command in Galilee under the Romans. A fortified cavern existed in the time of the Crusades. It is mentioned by William of Tyre, as situate in the country beyond the Jordan, sixteen Roman miles from Tiberias. The cave of Elijah is pretended to be shown, at the foot of Mount Sinai, in a chapel dedicated to him; and a hole near the altar is pointed out as the place where he lay.