Reconstructing biblical military campaigns using geomagnetic field data

This study presents 32 high-resolution geomagnetic intensity data points from Mesopotamia, spanning the 3rd to the 1st millennia BCE. These data contribute to rectifying geographic disparities in the resolution of the global archaeointensity curve that have hampered our understanding of geomagnetic field dynamics and the viability of applying archaeomagnetism as a method of absolute dating of archaeological objects. A lack of precise and well-dated intensity data in the region has also limited our ability to identify short-term fluctuations in the geomagnetic field, such as the Levantine Iron Age geomagnetic Anomaly (LIAA), a period of high field intensity from ca. 1050 to 550 BCE. This phenomenon has hitherto not been well-demonstrated in Mesopotamia, contrary to predictions from regional geomagnetic models. To address these issues, this study presents precise archaeomagnetic results from 32 inscribed baked bricks, tightly dated to the reigns of 12 Mesopotamian kings through interpretation of their inscriptions. Results confirm the presence of the high field values of the LIAA in Mesopotamia during the first millennium BCE and drastically increase the resolution of the archaeointensity curve for the 3rd–1st millennia BCE. This research establishes a baseline for the use of archaeomagnetic analysis as an absolute dating technique for archaeological materials from Mesopotamia.

Proceedings of the National Academy of Sciences, 2023

This study presents 32 high-resolution geomagnetic intensity data points from Mesopotamia, spanning the 3rd to the 1st millennia BCE. These data contribute to rectifying geographic disparities in the resolution of the global archaeointensity curve that have hampered our understanding of geomagnetic field dynamics and the viability of applying archaeomagnetism as a method of absolute dating of archaeological objects. A lack of precise and well-dated intensity data in the region has also limited our ability to identify short-term fluctuations in the geomagnetic field, such as the Levantine Iron Age geomagnetic Anomaly (LIAA), a period of high field intensity from ca. 1050 to 550 BCE. This phenomenon has hitherto not been well-demonstrated in Mesopotamia, contrary to predictions from regional geomagnetic models. To address these issues, this study presents precise archaeomagnetic results from 32 inscribed baked bricks, tightly dated to the reigns of 12 Mesopotamian kings through interpretation of their inscriptions. Results confirm the presence of the high field values of the LIAA in Mesopotamia during the first millennium BCE and drastically increase the resolution of the archaeointensity curve for the 3rd–1st millennia BCE. This research establishes a baseline for the use of archaeomagnetic analysis as an absolute dating technique for archaeological materials from Mesopotamia.

Meaningful interpretation of past human culture and political geography requires an accurate chronology that can be correlated with our modern calendar. The timing of seminal events during the Levant Iron Age is hotly debated because conventional dating methods are limited by subjective interpretations and analytical ambiguities. Archaeomagnetism, the study of the Earth’s ancient geomagnetic field recorded by heat-treated anthropogenic objects, can provide a complementary dating tool to build a stronger, more robust chronology for the Iron Age. Here we present a description of the field of archaeomagnetic dating, and a brief overview of the chronological issues and radiocarbon dating problems for the Iron Age Levant. We also present a new Near East Archaeomagnetic Curve (NEAC) model for the region along with preliminary data from Khirbet Summeily, Israel.

Earth and Planetary Science Letters, 2012

The distribution of archaeomagnetic data in eastern Europe and the Near and Middle East shows a remarkable gap in Turkey. This study presents the first archaeomagnetic results from five different mounds in southeast Turkey, the northern part of Mesopotamia. The rock magnetic experiments indicate that in the majority of the samples the dominant magnetic carrier is magnetite, which is stable to heating to temperatures of 700 1C. In general, the demagnetization diagrams are single component and all five sets display well-defined characteristic magnetizations and clustered directions. For the period between 2500 and 700 BCE, the declinations are between 3501 and 201 while inclinations are in the range of 49-641. The directional results are compared with the global geomagnetic field models (CALS7k.2, ARCH3k_cst.1 and CALS3k.4) and the data from the archaeomagnetic database GEOMA-GIA50v2. The results are coherent with both the data and the models except for two nearcontemporaneous sets dating $ 2000 BCE, which are offset to the east by more than 201 with respect to CALS7k.2. Archaeointensity measurements were made using the microwave and conventional thermal Thellier methods applied to five sets of samples (four furnaces and a mud-brick wall). These yielded comparable and intriguing results. While those from the furnaces are slightly higher than the CALS7k.2 model and in agreement with the GEOMAGIA50v2 and the Middle East data, the results from the mud-brick wall suggest a high intensity of 100.8 mT (17.7 Â 10 22 Am 2 ) at $ 1000 BCE. This result is in excellent agreement with recent claims of extremely high intensity measured in other regions of the Middle East for this time period though less consistent with these being associated with extremely short-lived events. Finally, we discuss our new and other recently published archaeointensity results in terms of geomagnetic intensity versus climate.

Geochemistry, Geophysics, Geosystems, 2020

Regional and global geomagnetic models of the Holocene, which describe the time evolution of the geomagnetic field vector, are of interest to a number of research fields, including exploration of the geodynamo

We present results from an archaeointensity investigation based on a relatively unexploited recording medium, copper slag deposits. Together with a recently improved experimental design for the archaeointensity experiment, we demonstrate the applicability of this medium, as well as other archaeometallurgical artifacts, for the study of the ancient geomagnetic field intensity. In addition to archaeointensity data from well-dated archaeological contexts, we obtained reliable archaeointensity results from poorly dated or contentious archaeometallurgical sites in the Southern Levant. These results shed new light on the dating of these sites, among them the copper smelting installation of Timna 39ba site that has important implications for the beginning of metallurgy during the fifth millennium BCE. The paper also aims to introduce archaeointensity research to the archaeologist scholar, and to encourage further collaboration between the disciplines in future research.

Data from the marriage of paleomagnetism and archaeology (archaeomagnetism) are the backbone of attempts to create geomagnetic field models for ancient times. Paleointensity experimental design has been the focus of intensive efforts and the requirements and shortcomings are increasingly well understood. Some archaeological materials have excellent age control from inscriptions, which can be tied to a given decade or even a specific year in some cases. In this study, we analyzed fired mud bricks used for the construction of the Ishtar Gate, the entrance complex to the ancient city of Babylon in Southern Mesopotamia. We were able to extract reliable intensity data from all three phases of the gate, the earliest of which includes bricks inscribed with the name of King Nebuchadnezzar II (605 to 562 BCE). These results (1) add high quality intensity data to a region relatively unexplored so far (Southern Mesopotamia), (2) contribute to a better understanding of paleosecular variation in this region, and the development of an archaeomagnetic dating reference for one of the key regions in the history of human civilizations; (3) demonstrate the potential of inscribed bricks (glazed and unglazed), a common material in ancient Mesopotamia, to archaeomagnetic studies; and (4) suggest that the gate complex was constructed some time after the Babylonian conquest of Jerusalem, and that there were no substantial chronological gaps in the construction of each consecutive phase. The best fit of our data (averaging 136±2.1 ZAm 2) with those of the reference curve (the Levantine Archaeomagnetic Curve) is 569 BCE.

Israel Journal of Earth Sciences, 2003

Paleomagnetic tests on two archaeological structures from the Crusader fortress Vadum Iacob (Ateret) reveal the use of these structures as an oven and a lime kiln. These fireplaces enable determination of the local direction and intensity of the geomagnetic field on 24 August 1179, when its construction was terminated by the Arab conquest. Stable field directions of the natural remanent magnetization were obtained in 31 specimens from a total of 16 building stones taken from the two archeological structures in the site. We consider the results as a negative stability test, indicating that a temperature above the Curie temperature erased the original in situ magnetization of each building stone when the stones were part of the fireplaces, and a new magnetization was acquired on the day the fire was extinguished. The mean magnetic directions of the two installations are statistically indistinguishable 013º/48º; α 95 = 6.5° and 017º/58º ; α 95 = 9.1º. The paleointensity of the Earth's magnetic field obtained by the original Thellier double-heating method from 8 basalt specimens from the lime oven is 72 ± 7 µT, about 1.8 times the current field. We demonstrate how the geophysical study of paleomagnetism helped resolve an archaeological question and how the archaeological and historical study helped resolve the dating of a geophysical feature.

PEASA, 2024

The study of the magnetization of artifacts discovered at archaeological sites, such as ceramics or hearth remnants, is known as archaeomagnetism. This technique is based on the idea that some materials get magnetized in the direction and intensity of the Earth's magnetic field at the time when heated or exposed to extreme heat. Development in the field has been made to improve magnetometer devices and sample size, as well as measuring techniques of thermal remanent magnetization. It helped to study the variation of the complex Earth's magnetic field or geomagnetic field (GMF) for both geophysical and archaeological dating benefits. The rapid change in GMF within a few hundred or decades, as being of genuine origin or methodological and sample unsuitability has been a matter of debate. Data from about 40 years ago derived from well-dated Byzantine churches that first confirmed such geomagnetic spikes is discussed along with recent archaeomagnetic data from Mesopotamian inscribed bricks and Levantine slags.

Journal of Geophysical Research: Solid Earth, 2022

Our understanding of geomagnetic field intensity prior to the era of direct instrumental measurements relies on paleointensity analysis of rocks and archaeological materials that serve as magnetic recorders. Only in rare cases are absolute paleointensity data sets continuous over millennial timescales, in sub-centennial resolution, and directly dated using radiocarbon. As a result, fundamental properties of the geomagnetic field, such as its maximum intensity and rate of change have remained a subject of lively discussion. Here, we place firm constraints on these two quantities using Bayesian modeling of well-dated archaeomagnetic intensity data from the Levant and Upper Mesopotamia. We report new data from 23 groups of pottery collected from 18 consecutive radiocarbon-dated archaeological strata from Tel Megiddo, Israel. In the Near East, the period of 1700–550 BCE is represented by 84 groups of archaeological artifacts, 55 of which were dated using radiocarbon or a direct link to clear historically dated events, providing unprecedented sub-century resolution. Moreover, stratigraphic relationships between samples collected from multi-layered sites enable further refinement of the data ages. The Bayesian curve shows four geomagnetic spikes between 1050 and 600 BCE, with virtual axial dipole moment (VADM) reaching values of 155–162 ZAm2, much higher than any prediction from geomagnetic field models. Rates of change associated with the four spikes are ∼0.35–0.55 μT/year (∼0.7–1.1 ZAm2/year), at least twice the maximum rate inferred from direct observations spanning the past 180 years. The increase from 1750 to 1030 BCE (73–161 ZAm2) depicts the Holocene's largest change in field intensity.

Frontiers in Earth Science

The large and well-studied archaeological record of Israel offers a unique opportunity for collecting high resolution archaeomagnetic data from the past several millennia. Here, we initiate the first catalog of archaeomagnetic directions from Israel, with data covering the past four millennia. The catalog consists of 76 directions, of which 47 fulfill quality selection criteria with Fisher precision parameter (k) ≥ 60, 95% cone of confidence (α 95) < 6 • and number of specimens per site (n) ≥ 8. The new catalog complements our published paleointensity data from the Levant and enables testing the hypothesis of a regional geomagnetic anomaly in the Levant during the Iron Age proposed by Shaar et al. (2016, 2017). Most of the archaeomagnetic directions show <15 • angular deviations from an axial dipole field. However, we observe in the tenth and ninth century BCE short intervals with field directions that are 19 •-22 • different from an axial dipole field and inclinations that are 20 •-22 • steeper than an axial dipole field. The beginning of the first millennium BCE is also characterized with fast secular variation rates. The new catalog provides additional support to the Levantine Iron Age Anomaly hypothesis.

We present results from an archaeointensity investigation based on a relatively unexploited recording medium, copper slag deposits. Together with a recently improved experimental design for the archaeointensity experiment, we demonstrate the applicability of this medium, as well as other archaeometallurgical artifacts, for the study of the ancient geomagnetic field intensity. In addition to archaeointensity data from well-dated archaeological contexts, we obtained reliable archaeointensity results from poorly dated or contentious archaeometallurgical sites in the Southern Levant. These results shed new light on the dating of these sites, among them the copper smelting installation of Timna 39ba site that has important implications for the beginning of metallurgy during the fifth millennium BCE. The paper also aims to introduce archaeointensity research to the archaeologist scholar, and to encourage further collaboration between the disciplines in future research.

Earth's magnetic field, one of the most enigmatic physical phenomena of the planet, is constantly changing on various time scales, from decades to millennia and longer. The reconstruction of geomagnetic field behavior in periods predating direct observations with modern instrumentation is based on geological and archaeological materials and has the twin challenges of (i) the accuracy of ancient paleomagnetic estimates and (ii) the dating of the archaeological material. Here we address the latter by using a set of storage jar handles (fired clay) stamped by royal seals as part of the ancient administrative system in Judah (Jerusalem and its vicinity). The typology of the stamp impressions, which corresponds to changes in the political entities ruling this area, provides excellent age constraints for the firing event of these artifacts. Together with rigorous paleomagnetic experimental procedures, this study yielded an unparalleled record of the geomagnetic field intensity during the eighth to second centuries BCE. The new record constitutes a substantial advance in our knowledge of past geomagnetic field variations in the southern Levant. Although it demonstrates a relatively stable and gradually declining field during the sixth to second centuries BCE, the new record provides further support for a short interval of extreme high values during the late eighth century BCE. The rate of change during this " geo-magnetic spike " [defined as virtual axial dipole moment > 160 ZAm 2 (10 21 Am 2)] is further constrained by the new data, which indicate an extremely rapid weakening of the field (losing ∼27% of its strength over ca. 30 y). archaeomagnetism | archaeointensity | levantine archaeomagnetic curve | paleosecular variation | archaeomagnetic spikes

Constraining secular variation of the Earth's magnetic field strength in the past is fundamental to understanding shortterm processes of the geodynamo. Such records also constitute a powerful and independent dating tool for archaeological sites and geological formations. In this study, we present 11 robust archaeointensity results from Pre-Pottery to Pottery Neolithic Jordan that are based on both clay and flint (chert) artifacts. Two of these results constitute the oldest archaeointensity data for the entire Levant, ancient Egypt, Turkey, and Mesopotamia, extending the archaeomagnetic reference curve for the Holocene. Virtual Axial Dipole Moments (VADMs) show that the Earth's magnetic field in the Southern Levant was weak (about two-thirds the present field) at around 7600 BCE, recovering its strength to greater than the present field around 7000 BCE, and gradually weakening again around 5200 BCE. In addition, successful results obtained from burnt flint demonstrate the potential of this very common, and yet rarely used, material in archaeomagnetic research, in particular for prehistoric periods from the first use of fire to the invention of pottery.

Physics of the Earth and Planetary Interiors, 2015