“The boulders in the tower’s base in and of themselves do not yield any information other than the fact that whoever placed them there had the ability to maneuver such heavy stones.
The separate, sequential layers of sediment were identified using microarchaeological tools and radiocarbon dating, and enabled the researchers to date the strata found at the base of the tower. “Scenarios for the construction of the tower during Middle Bronze Age (MB) and Iron Age II are considered, based on the new 14C [radiocarbon] data, yielding a series of dates, the latest of which falls in the terminal phases of the 9th century BCE, alongside previous excavation data,” according to the study.
Contrary to previous estimates, the date revealed by this radiocarbon dating was sometime around 900-800 BCE — nearly 1,000 years later than archaeologists had originally dated the tower, and well after the presumed reign of King David.
Developed in the late 1940s, radiocarbon dating is carried out with the use of accelerator mass spectrometric measurements of radiocarbon, a radioactive isotope of carbon.
According to the Weizmann Institute, it is precise up to ±20-40 years. Johanna Regev identified several clearly delineated strata of sediment, from which they collected samples of charcoal, seeds and bones.
Since 2012, the IAA has performed excavations along the outer, eastern face of the Spring Tower, part of the citadel. Joe Uziel and Nahshon Szanton observed that the tower does not sit on bedrock but rather on layers of soil, according to the recent study, published June 6 through Cambridge University Press.
The discovery of these organically based sediment layers opened up the possibility of analyzing the soil through radiocarbon dating, rather than a dating based on the shapes and materials of discovered artifacts that was previously performed.The findings, based on soil samples taken from under a seven-meter thick walled tower, shave nearly a thousand years from previous archaeological dating of the structure, which placed it c.1700 BCE — and contradict a presumed biblical linkage to the site.“I agree with one of the possibilities raised by the authors, that the radiocarbon dates come from under a restored sector of the eastern wall of the spring tower.Accordingly, the spring tower could have been built in the Middle Bronze Age and restored in the late 9th century or even later,” says Finkelstein, who is a proponent of the idea that ancient Jerusalem had smaller, more modest city limits. Alkow professor of the Archaeology of Israel in the Bronze and Iron Ages at Tel Aviv University, “A Middle Bronze date for the original construction of the tower is supported by similarity to construction methods at places such as Shechem and Shiloh.” (Finkelstein was director of excavations at biblical Shiloh in 1981-1984.) “If indeed an old tower was damaged and restored in the Iron Age, the question is when.The Spring Citadel was excavated in the City of David National Park by dozens of researchers led by Professor Ronny Reich of the University of Haifa and Eli Shukrun of the Israel Antiquities Authority and dated to 3,800 years ago.