In the oldest part of Jerusalem, a remarkable underground shaft, 40 feet long, connects two tunnels—one longer and higher, the other shorter and lower; the lower tunnel leads to the city’s ancient water supply, the Gihon Spring. The shaft was discovered in the 1860s by that great British explorer of Jerusalem, Charles Warren; it is now known as Warren’s Shaft.
For many years, Warren’s Shaft was famous because it was thought that King David’s general, Joab, may have gotten inside the well-defended city (subsequently capturing it) by climbing up this shaft. The Bible tells us that David said that whoever would conquer Jerusalem would get up the tsinnor, usually translated watershaft (2 Samuel 5:8). Warren’s Shaft, it was argued, was the tsinnor.
Everything about this story is hotly debated. Some say tsinnor does not mean watershaft. Others say no one could climb such a slippery vertical shaft. Still others say the shaft is a natural karstic chimney that was never used to draw water. And a recent excavation by Ronny Reich and Eli Shukron has shown that the floor of the upper tunnel did not reach the top of the shaft until the eighth century B.C.E., long after King David had conquered the city. Jerusalem may have been conquered when Joab entered it via a tunnel that led from inside the city wall to the Gihon Spring, but, if he did, it wasn’t Warren’s Shaft.
That, however, did not settle the question of whether Warren’s Shaft was ever used to draw water, even after the eighth century B.C.E. Reich and Shukron have said Warren’s Shaft was never used to draw water.a Avraham Faust, another Israeli archaeologist, has countered that it was.b Now, a Jerusalem geologist enters the debate, using geological evidence to show that Reich and Shukron were right and Faust is wrong.—Ed.
Despite arguments to the contrary, Avraham Faust argues that Warren’s Shaft was used to draw water by residents of ancient Jerusalem; they would simply drop a bucket on a rope down the shaft, fill it with water from the cave at the bottom (water that got there via a tunnel from the Gihon Spring), and then draw the bucket back up the shaft. It is quite possible, he argues, to draw a bucket of water straight up from the bottom, perhaps while standing on a wooden platform at the top of the shaft so the water-drawer would be directly over the center of the shaft and could draw a straight vertical bead to the bottom. Faust points out that Père Hugues-Louis Vincent, the Dominican father who recorded the activities of the so-called Parker Mission,c observed that mud in buckets was drawn up the shaft by the Parker excavation team when they cleaned the tunnel in 1909–1911.
This is Faust’s principal argument. But mud is not the same as water. And the fact that it is possible to draw water up the shaft does not mean that, in fact, it was so used in antiquity.
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Warren’s Shaft is a natural karstic dissolution flue formed by dripping water more than 400,000 years ago. (We have recently dated it by the uranium-thorium radiometric method.1) The shaft was generated along rock fractures that trended in approximately an east-west direction. But when the shaft reached a depth of about 40 feet, it encountered a set of fractures that trended in approximately a north-south direction. At this point, the dissolution process formed a cave for a distance of about 6 feet. But since the fractures are continuous, the vertical shaft continued for a few yards below the cave on the eastern side.
Like other karstic dissolution caves, water has been passing through here for hundreds of thousands of years, first dissolving the local limestone and dolomite and later leaving deposits of carbonate sediment (flowstone, stalactites and stalagmites) along walls and floors. This is clearly an area of water transit and not water accumulation. There is simply too much space allowing water to escape beneath this shaft for the cave to be used for water collection. (That is why a wall was built in the short tunnel ending at the cave entrance to prevent water from entering the cave from the Gihon Spring tunnel; the ancients did not want to lose water by allowing it to flow into the cave.)
All of the tunnels beneath the City of David that carried or contained water were well-plastered. We recently dated the earliest plaster in the most famous of these tunnels—Hezekiah’s tunnel—and determined that it indeed dated to Hezekiah’s time (about 700 B.C.E.),2 but segments of the system were replastered in later times as well, including during the Byzantine (524–638 C.E.), Mameluke (1291–1516 C.E.) and Ottoman (1516–1917 C.E.) periods.
Plastering was not a luxury carried out for aesthetic purposes but was a necessity for retaining water. These underground waterworks contain a profusion of fractures, joints and karstic dissolution caves and channels through which water could easily escape.
The karstic cave at the bottom of Warren’s Shaft, however, reveals no trace of plaster. It was never plastered because it was never meant to hold water running into it from the spring.
What appears to be a water line at about chest height in the cave is in fact a mud line. It is gently inclined to the northeast and delineates the upper level of mud fill in the cave.
Had this cave ever held water for any length of time, we would find on the walls and floor deposits of siltstone and also a type of travertine (a mineral deposit) known as tufa. Siltstone is simply quartzose silt that has been settling out of the spring water ever since these underground waterworks were dug to channel the water from the Gihon Spring. We see it in a veneer of dark and very tough sediment that covers segments of the floor plaster, for example in Hezekiah’s Tunnel. Layers of silty tufa also cover segments of walls, in particular near the southern exit of Hezekiah’s Tunnel.
But there is no evidence of this revealing sedimentary activity in the cave at the bottom of Warren’s Shaft. The reason is clear: The cave at the bottom of Warren’s Shaft never held water for any significant length of time. Therefore Warren’s Shaft was never used to draw water.
Faust claims that the tunnel between the cave and the Gihon Spring was dug to direct the spring water into the cave. Since the spring is lower than the cave, Faust speculates that an ancient dam was reused in order to raise the level of water so that it could enter the cave below Warren’s Shaft. But, as we have seen, there is no evidence that the cave ever held water. One of the two damming walls constructed by ancient Jerusalemites east of the spring was made to block the spring waters from their natural flow east into the Kidron Valley, and the second was built to block flowage into the easternmost channel (known as Channel I).
Faust also contends that the tunnel between the spring and the cave was dug from the spring to the cave. He argues that if the tunnel had been dug from the cave, the diggers would have enlarged the cave to enable them to maneuver more easily. But the fact is that the cave was modified. On a careful examination of the cave, we found tool marks plainly visible on the west, south and east walls of the cave, which was indeed enlarged, most likely as a way-station to accommodate the removal of rubbish during excavation of Hezekiah’s Tunnel. Moreover, tool marks on the tunnel walls, as Vincent observed, show that it was dug in two stages, from west to east, from the cave toward the spring. This is shown not only by the tool marks, but also in the character and orientation of so-called “correction niches,” places where the diggers had to correct their direction of progress.
Did Faust ever visit the site before writing his article? It is not clear that he did. If not, he joins the many other armchair theoreticians who have unsuccessfully attempted to unravel the secrets of ancient Jerusalem’s underground waterworks.
In the oldest part of Jerusalem, a remarkable underground shaft, 40 feet long, connects two tunnels—one longer and higher, the other shorter and lower; the lower tunnel leads to the city’s ancient water supply, the Gihon Spring. The shaft was discovered in the 1860s by that great British explorer of Jerusalem, Charles Warren; it is now known as Warren’s Shaft. For many years, Warren’s Shaft was famous because it was thought that King David’s general, Joab, may have gotten inside the well-defended city (subsequently capturing it) by climbing up this shaft. The Bible tells us that David said that […]
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See Amos Frumkin, Aryeh Shimron and Jeff Rosenbaum, “Radiometric Dating of the Siloam Tunnel, Jerusalem,” Nature 425, September 11, 2003, pp. 169–171. Scientists use the uranium-thorium radiometric dating technique to establish the age of calcite (calcium carbonate) in coral, shells and especially cave and spring travertine, and to a somewhat lesser extent for apatite (calcium phosphate) and related materials in bone and teeth. What allows the uranium-thorium “clock” to work is that two isotopes of uranium, 234U and 238U, spontaneously decay to an isotope of thorium, 230Th. When calcite or apatite precipitate, they always take on some impurities such as uranium—but very little thorium. Once precipitation occurs, the uranium-thorium clock starts ticking. Atoms of uranium start converting to atoms of thorium at a constant rate. As time passes, there are progressively fewer 234U and 238U atoms and correspondingly more 230Th atoms. The ratio of 230Th/(234U + 238U) is the measure of how much time has elapsed. When the calcite or apatite first crystallizes, the ratio is equal to zero; over time the ratio increases. The uranium-thorium clock is useful for dating materials between one thousand and a few hundred thousand years old.—Ed., with thanks to James Harrell, a geologist at the University of Toledo.
