Israeli researchers say magnetic fields provide way to securely date biblical events

An interdisciplinary team of Israeli scientists and archaeologists may have come one step closer to “proving” the historical veracity of the Bible.

Through archaeomagnetic dating, archaeologists can now combine the holy trinity of modern biblical archaeology — the biblical text’s account, extrabiblical historical sources and scientifically excavated artifacts — to do precise dating of destruction layers from military conquests described in the Bible.

The method utilizes excavation layers that have already been reliably dated to create baseline anchors for the archaeomagnetic data, which can then be applied to other sites that until now had been impossible to confidently date. The more anchors are created, the researchers say, the more finely calibrated the dating method will become.

“It all fit perfectly — better than I could even imagine — really proving the power of this method,” said Tel Aviv University doctoral student Yoav Vaknin, the lead author of a study that tried out the method on 20 excavation layers, some of which could not previously be securely dated. The article, titled “Reconstructing biblical military campaigns using geomagnetic field data,” was published Tuesday in the open-sourced scientific journal Proceedings of the National Academy of Sciences of the USA (PNAS).

The magnetic field is a constantly shifting invisible shield stemming from magnetic ore in the Earth’s core, which scientists believe may hold a key for the creation and continuation of life as we know it.

Archaeological findings such as pottery sherds, bricks, roof tiles and furnaces record the Earth’s magnetic field as they are burned at high temperatures, causing their magnetic minerals to be re-magnetized to the direction and magnitude of the field when they were heated. This data is similar to a fingerprint and is unique to the date it was recorded.

The destruction layers of biblical military conquests provide copious materials from the slash-and-burn campaigns.

The 586 BCE Babylonian destruction of ancient Jerusalem, attested to in biblical and extra-biblical sources, gave Vaknin the perfect way to start calibrating the new dating tool. In 2020, Vaknin published an article shoring up the archaeomagnetic data of this anchor event.

There are several other military conquests dotting the Bible that are also confirmed in extra-biblical sources, which create more anchors in time. For example, the Bible states in 2 Kings 12:18 that Gath of the Philistines was destroyed by Hazael, king of Aram-Damascus.

Located in the Judean foothills, Gath is being excavated under the almost three decades-long Tell es-Safi/Gath Archaeological Project led by Bar Ilan University Prof. Aren Maeir.

Gath, Maeir told The Times of Israel in an email, “was one of the sites that had a well-dated destruction (Hazael’s destruction, ca. 830 BCE) and could be used to base this [dating method] in relationship to other known destructions (such as Sennacherib at Lachish, 701 BCE) and compare to those whose dating was not clear.”

Radiocarbon dating, which is generally reliable, is less useful for much of the biblical narrative’s span due to a calibration issue covering circa 800-400 BCE, known as the Hallstatt plateau. The archaeomagnetic dating technique, used by Earth scientists to reconstruct the globe’s historical magnetic field, could make up for that shortfall and eventually serve as a normative, complementary dating tool in every biblical archaeologist’s toolbox.

Dr. Yoav Vaknin (Tel Aviv University)

“This research demonstrates how an archaeointensity curve constructed from a dense archaeomagnetic dataset in which the chronology rests on radiocarbon (for periods before the eighth century BCE) and firm historical ages (from the eighth century BCE and on) can be used as a powerful chronological tool. This is especially useful during the Hallstatt Plateau (ca. 800–400 BCE), a period in which the resolution of radiocarbon dating is limited,” reads the Vaknin paper.

In the current paper, the scientists reconstructed the direction and/or intensity of Earth’s magnetic field recorded in 20 burnt destruction layers that were exposed at 17 archaeological sites and in two ceramic assemblages. The study included the analysis of 1,186 specimens from 144 samples and tested for magnetic direction and intensity.

“This is the first paper where we have a large enough database to say we can actually do archaeomagnetic dating which is reliable,” said Vaknin. “And the results were astounding.”

Archaeologist Aren Maeir (left) supervises at an 830 BCE destruction layer at the Tel Tzafit/Gath Archaeological Project, July 2018. (Amanda Borschel-Dan/Times of Israel)

Vaknin told The Times of Israel that a few things surprised him while he was conducting this research.

“One is the agreement between sites that presumably were destroyed at a certain time — both [magnetic] direction and also intensity. The best example is the destructions attributed to Hazael at about 830 BCE. We got perfect agreement between four sites in intensity, and in most of them we also have direction results,” he said. The sites included Gath, Tel Rehov Stratum IV, Horvat Tevet Level V, and Tel Zayit Level XII.

At another site, Tel Beth She’an, a decades-long argument over when the destruction occurred was put to rest through the new dating tool.

“The dating was open. There was no clear date, but within the age range, the higher probability according to the excavator Ami Mazar, who is also a co-author, it’s most likely later, at about 830 BCE — also, like Hazael. Our results showed clearly that [the destruction] cannot be by Hazael and that it must be earlier, even much earlier. So that was a very interesting surprise,” he said.

Finding that Beth She’an was probably destroyed 70-100 years earlier than previously thought places the city’s downfall at the time of the military campaign of the Egyptian Pharaoh Shoshenq, the researchers believe. According to a TAU press release, this Holy Land campaign is described in the Bible and in an inscription on a wall of the Temple of Amun in Karnak, Egypt, which mentions Beth-Shean as one of his conquests.

Burnt mud bricks (Yoav Vaknin)

The nuts and bolts

The magnetic field serves as the Earth’s shield from cosmic radiation and charged particles from the sun. Magnetic north is used as a navigation tool by man — think compasses — and by many birds and marine mammals who are naturally attuned. It shifts over time and each era has its own signal or “fingerprint” of intensity and direction.

The same signal found at another location in the Levant is almost certainly from the same date, allowing archaeologists to use it as a tool for securely dating, for example, the cascading downfall of the Kingdom of Judah, which spanned several decades.

“The magnetic field is invisible, but it plays a critical role in the life of our planet. Without the geomagnetic field, nothing on Earth would be as it is — maybe life wouldn’t have evolved without it,” Hebrew University Prof. Ron Shaar, a co-author of the study, told The Times of Israel while discussing the earlier 586 BCE research.

Map of the studied destruction layers and the different military campaigns. (Itamar Ben-Ezra)

“The magnetic field is generated by chaotic electrical and fluid currents at the Earth’s core. We geophysicists are trying to understand how it changes with time, because it is constantly changing, and we are trying to understand why, and what the mechanisms are that drive the changes,” said Shaar.

According to Vaknin, to perform archaeomagnetic dating, scientists measure samples of burnt features or artifacts such as burnt mudbricks or ceramics for magnetic intensity and direction.

The more the technique is performed on archaeological sites that can serve as “anchor dates” — dates that have a high certainty of historicity, such as the Tisha B’Av destruction of Jerusalem in 586 BCE — the more the researchers can compare results and build more complete dating tables — as well as computer models of one of the most enigmatic subjects in physics, the magnetic field.

Vaknin explained that the magnetic field isn’t the same all over the world and while there are aspects that are global, there are also anomalies. His work and that of the 20-odd researchers who worked on this article is concentrated in the Levant. Their results, he said, formed a statistical curve he calls the Levantine Archaeomagnetic Curve or “LAC,” which encompasses a 1,000- to 1,500-kilometer (600–9– miles) radius including southern Turkey, northern Egypt, the Holy Land, Syria and beyond.

Artifacts such as ceramics from the Levant can be tested and given a range of probable dates. Unfortunately, Vaknin said, the intensity of the magnetic field doesn’t change in a linear fashion, but rather has spikes and dips throughout the years. In the case of ceramics, typology narrows down the range to a certain century and then, based on an artifact’s fingerprint, he can compare the magnetic signal to data points already on the curve and can likely provide a date of within a few decades.

“The new dating tool is unique because it is based on geomagnetic data from sites whose exact destruction dates are known from historical sources,” Tel Aviv University Prof. Oded Lipschits said in a press release. “By combining precise historical information with advanced, comprehensive archaeological research, we were able to base the magnetic method on reliably anchored chronology.”

Vaknin conducted his paleomagnetic experiments under the direction of Shaar at the magnetically shielded paleomagnetic laboratory at the Institute of Earth Sciences located at the Hebrew University of Jerusalem’s Givat Ram Campus.

TAU PhD student Yoav Vaknin takes measurements of a floor that collapsed during the 586 BCE destruction of Jerusalem by the Babylonians at excavations in the City of David Park in Jerusalem. (Shai Halevi/Israel Antiquities Authority)

While the archaeologist and the Earth scientist’s motivations may be different, they both hope to ramp up the testing and continue filling out the computer model curves of the Earth’s magnetic fields.

“We are sitting in Israel on a gold mine! It’s unbelievable,” said Shaar. “We have immediate access to an infinite number of artifacts we can measure and date and understand the field in the past.”

Happily, it doesn’t take a gold mine to fund the testing. “Regarding the price, it’s not too expensive. Sampling is very simple. Once you have the samples you work with them in the lab. The lab is very special and unique. There is only one lab like that in Israel. But once you have the lab, running the samples is not too expensive,” said Vaknin.

“I really hope and I think that it’s going to become part of the toolbox of archaeologists here in Israel and in general in the world,” said Vaknin. “The more data we have, the more accurate and reliable this dating method is, and I think we are there already now.”