Fire and collapse: Untangling the formation of destruction layers using archaeomagnetism

Abstract

Historical events are sometimes expressed in destruction layers. We present here a study in which aspects of construction, destruction, and chronostratigraphy of fired mud bricks were explored using archaeomagnetism, infrared spectroscopy, and micromorphology. We measured 88 oriented samples mostly collected from one stratum, dated ca. 1000 B.C.E., representing a destroyed late Canaanite (late Iron Age I) city in Tel Megiddo, Israel. Firing temperatures, evaluated from infrared spectroscopy, micromorphology, and high‐temperature magnetic susceptibility cycles, range between 300°C and 800°C. Samples studied in one archaeomagnetic site yield a single stable magnetization vector in demagnetization experiments. Archaeomagnetic site means of three standing walls are grouped near the expected direction of the ancient geomagnetic field. We propose that walls in the destruction layer were constructed from sun‐dried mud bricks that later burned during the destruction. Collapsed bricks and tilted walls show variable directions, diagnostic for the relative timing of collapse and cooling of bricks, during and following the destruction event. In addition, we attempt to assign stratigraphic affiliation based on archaeomagnetic considerations to standing walls, which are spatially disconnected from the studied destruction layer. Altogether, this study demonstrates the usefulness of archaeomagnetism to understanding site formation processes related to fire and destruction.

The First Catalog of Archaeomagnetic Directions From Israel With 4,000 Years of Geomagnetic Secular Variations

“…Hence, the age of the ovens are typically dated by the age of living stratum in which it was found. Burnt walls ( Figure 2B) are in-situ remains of large mudbrick structures, which were burnt as a whole during historical destruction events (e.g., Shahack-Gross et al, 2018). In the case of a large conflagration there may be a large amount of burnt organic material that can be directly dated and crosscorrelated with known historical military campaigns, leading to high precision dating, sometimes with an uncertainty of several years (e.g., Tel Megiddo; Finkelstein and Piasetzky, 2009), Tel Hazor (Sandhaus, 2013;Zuckerman, 2013), Tel 'Eton (Faust, 2008), Bethsaida (Arav, 2014), and Lachish (Ussishkin, 1990)].…”

“…of a continuous secular variation curve, archaeo-chronological insights can be obtained by merely comparing archaeomagnetic data from structure whose age is not tightly constrained, with the available data. The burnt structure MGDF from Shahack-Gross et al (2018) is an example of this approach. For dating the destruction that caused the fire at this archaeological level, Shahack-Gross et al (2018) compared the paleomagnetic direction of MGDF with the available archaeomagnetic directions of periods with known destructions in Megiddo (Late Bronze III, Late Iron I, Iron IIA, and Iron IIB) and found that only one period fit to the archaeomagnetic data.…”

“…Our study area is located in an important geographic area that extends the densely scattered data from Europe to the southeast. To date, only several archaeomagnetic directions from Israel were published in journal articles (Aitken and Hawley, 1967;Segal et al, 2003;Shaar et al, 2016;Shahack-Gross et al, 2018). However, there are considerable unpublished data that are available only as unpublished theses (Segal, 2003;Hassul, 2015).…”

The Earth’s magnetic field in Jerusalem during the Babylonian destruction: A unique reference for field behavior and an anchor for archaeomagnetic dating

“…In Western Europe this dating method has proven to be especially useful during periods in which high resolution radiocarbon dating is not possible [25]. Archaeomagnetism can also provide a powerful tool for reconstructing site formation processes [26][27][28][29].…”

Sediments vs. Historical narratives: The use of soil magnetic properties to evaluate the existence of a historical fire in an 18th century Spanish fort (Patagonia, Argentina)

“…Combustion features like hearths, kilns, ovens and different intentional or un-intentional space-circumscribed fire structures has been studied archaeologically to answer questions related to the hominization process, pyrotechnologies, intensity of human occupation, resource management, conflagration events, space functionality and taphonomic processes. A this regard, different analytical techniques were applied, such as clay X-ray diffraction, thermoluminensce, anthracology, soil micromorphology, geochemistry, FTIR spectroscopy and infrared analysis, among others (e.g., Karkanas et al, 2002;Berna et al, 2007Berna et al, , 2012Mallol et al, 2007;Goldberg et al, 2009;Brodard et al, 2012;March et al, 2014;Gur-Arieh et al, 2014;Morley, 2017;Villagran et al, 2017;Ozán et al, 2019;Shahack-Gross et al, 2018). To a lesser extent, past combustion features have been tackled by magnetic analyses to discuss paleotemperatures, the geomagnetic field evolution (i.e., archaeomagnetism) and postdepositional processes (e.g., Ellwood et al, 1998;Dalan, 2008;Brodard et al, 2012;Kapper et al, 2014;Morley, 2017;Ozán et al, 2015Ozán et al, , 2017Ozán et al, , 2019Shahack-Gross et al, 2018;Urban et al, 2019).…”