Archaeologists Devise a Better Clock for Biblical Times

When it comes to assigning dates to military campaigns described in the Bible, the parameters of the debate take on almost biblical proportions. Exactly when did the Amalekites wage war against the Hebrews in the wilderness? Did Joshua fight the Battle of Jericho in 1500 B.C. or in 1400 B.C. — or at all?

Such uncertainty exists, in part, because the radiocarbon analysis that scientists use to date organic remains is less accurate for certain epochs. And, in part, because archaeologists often disagree over what the timelines for different narratives should be. But a new technique, which makes use of consistently reliable geomagnetic data, allows scientists to study the history of the Levant with greater confidence.

Many materials, including rocks and soils, record the reversals and variations over time in earth’s invisible geomagnetic field. When ancient ceramics or mud bricks that contain ferromagnetic, or certain iron-bearing, minerals are heated to sufficiently high temperatures, the magnetic moments of the minerals behave like a compass needle, reflecting the orientation and intensity of the field at the time of burning. The new methodology can provide a sort of geobiblical clock.

“Based on the similarity or difference in the recorded magnetic signals, we can either corroborate or disprove hypotheses” about when certain layers of sediment might have been destroyed during biblical battles, said Yoav Vaknin, a doctoral candidate at Tel Aviv University and the Hebrew University at Jerusalem, who pioneered the technology. “It all fits together perfectly, better than I had ever imagined.”

Mr. Vaknin’s research, published this year in the Proceedings of the National Academy of Sciences, harnesses information from 20 international scholars to map out a geomagnetic data set of 21 layers of historical destruction across 17 sites in the Holy Land.

The project is an attempt to check the historical authenticity of Old Testament accounts of the Egyptian, Aramaean, Assyrian and Babylonian offensives against the Kingdoms of Israel and Judah, and conflicts between these two realms. For those readers without a scorecard, the principals included Shoshenq I (1 Kings 14: 25-26), Hazael (2 Kings 12:18), Jehoash (2 Kings 14:11-15), Tiglath-pileser III (2 Kings 15:29), Sennacherib (2 Kings 18-19) and Nebuchadnezzar (2 Kings 25:1-21).

“With this new data set, we can narrow things down to a decadal level,” said Thomas Levy, an archaeologist at the University of California, San Diego, who was not involved with the study. “That is super important when trying to connect ancient historical events to the archaeological record.”

The real significance of the research is in the interdisciplinary connections, said Oded Lipschits, an archaeologist and one of the study’s co-authors: Experts in the new technique, known as archaeomagnetism, gain “chronological anchors” from the work of archaeologists — footholds in the historical timeline. “And in return, archaeology gets a new tool for dating, whose main application is in the first millennium B.C., a period when radiocarbon is less effective and impossible to rely on.”

The study stands apart not only for its content, but also for its researchers. All but one of the study’s authors are archaeologists — many of them with contradictory views on biblical history and the chronology of the period.

Rather than provide absolute dates, Mr. Vaknin’s database compares magnetic readings of burned materials at various sites. Where historical evidence has already established precise timelines, nearby sites can also be dated.

To understand the mysterious mechanism of earth’s magnetic field, geophysicists track its changes throughout history by using archaeological relics — furnaces, ceramic shards and roof tiles — that contain ferromagnetic minerals.

In a 2020 paper, Mr. Vaknin and his colleagues used floor fragments and smashed pottery from a large, two-story building excavated in a Jerusalem parking lot to recreate Earth’s magnetic field, as it was on the ninth of the Hebrew month of Av, 586 B.C., which is recognized as the date when Nebuchadnezzar and his Babylonian army annihilated the First Temple and the city of Jerusalem.

The more recent study reconstructed the magnetic field recorded in burned remains at biblical sites in present-day Israel that were razed by fire. Using archaeomagnetic readings that have been preserved for millenniums in mud bricks, in a mud beehive and in two collections of ceramic objects and historical information from ancient inscriptions, the team analyzed layers of ruin left behind by military conflicts.

The findings help settle a longstanding debate over how exactly the Kingdom of Judah fell and disproves claims that the ancient settlement of Tel Beit She’an, a magnet for conflagrations and epic sieges, was razed in the ninth century B.C. by the Aramaean armies of Hazael of Damascus. Magnetic dating indicates instead that Beit She’an was burned to the ground some 70 to 100 years earlier; this links the destruction to the Egyptian pharaoh Shoshenq, whose campaign was described in the Hebrew Bible and in an inscription on a wall of the Temple of Amun in Karnak, Egypt, which mentions Beit She’an as one of the king’s conquests.

Curiously, other data indicate that, about a century later, Hazael’s soldiers set fire to several settlements: Tel Rehov, Tel Zayit and Horvat Tevet, in addition to Gath, one of the five royal cities of the Philistines (and home to Goliath), whose destruction is noted in 2 Kings 12:17. The study, which examined the geomagnetic records at all four sites at the time of demolition, strongly suggests that they were burned during the same military offensive, according to the researchers.

Mr. Vaknin spent four years pioneering the application of paleomagnetic research to biblical archaeology, aided by his doctoral advisers, Dr. Lipschits, Erez Ben-Yosef of Tel Aviv University and Ron Shaar of the Institute of Earth Sciences at the Hebrew University of Jerusalem.

Besides helping to date archaeological contexts, the technology provides invaluable information on Earth’s magnetic field, one of the most enigmatic phenomena in geoscience. “Since instrumental recording of the field started about 200 years ago, the field’s strength has declined, and there is a danger that we might lose it completely,” Dr. Ben-Yosef said. “Understanding this trend and how dangerous it is requires data on the past behavior of the field.”

Earth’s magnetosphere is a protective bubble that deflects solar winds, streams of charged particles from the sun that gust through the solar system, and cosmic rays from deep space. Scientists theorize that the magnetic field is generated by a layer of molten iron and nickel in the planet’s outer core, about 1,800 miles below the surface, that is in continual flux around a solid iron core. As ferromagnetic particles in ancient artifacts cool, their magnetic moments are baked into the alignment. So long as the objects don’t heat up again, they will retain what is effectively a fossilized magnetic field. Each reheating beyond a certain temperature wipes out all previously recorded magnetic signals, so that the date is always of the most recent firing.

From around 800 to 400 B.C., as a result of changes in the percentage of radiocarbon in the atmosphere, the resolution of radiocarbon dating during those years is so limited that archaeologists seldom use it.

Dr. Ben-Yosef said he hoped that the new dating method would finally settle questions about the fall of the Kingdom of Judah. While it is widely accepted that the Babylonians laid waste to the Judean polity in 586 B.C., some researchers, relying on historical and archaeological evidence, argue that the invaders were not solely responsible. The intensity of the magnetic field as recorded in the destruction layer of the site of Malhata — a city on the southern periphery of Judah — is different and significantly lower than the one recorded in the Babylonian destruction of Jerusalem, the capital of the kingdom.” This means that the two destructions cannot be related to the same event,” Dr. Ben-Yosef said.

The archaeomagnetic data provided clear evidence that Malhata was destroyed decades later, a scenario that fits the notion that the Edomites, Judah’s southern neighbors, took advantage of the weakness of the Judahites after the Babylonian attack, decimated their southern cities and raided their territory.

“These events are reflected in the Hebrew Bible,” Dr. Ben-Yosef said. “They explain the animosity toward the Edomites by several prophets, notably Obadiah.”

Scholars who had partly absolved the Babylonians should feel vindicated, he added. “Now, the magnetic results support their hypothesis. The big deal about this research is that after decades of work on establishing a reference database, we finally reap the fruits of our labor, and what we saw has become a potent dating tool in biblical archaeology that, undoubtedly, will become part of the tool kit of archaeologists working in the Holy Land.”