Lior Regev

Decoupling Local Disorder and Optical Effects in Infrared Spectra: Differentiating Between Calcites with Different Origins

Infrared spectral peak broadening due to atomic disorder and narrowing due to particle-size-related optical absorption effects can be decoupled experimentally and theoretically. Applied to different sources of polycrystalline calcite, the method provides a powerful diagnostic tool for archaeology, geology, and materials/biomaterials science.

The onset of faba bean farming in the Southern Levant.

Even though the faba bean (Vicia faba L.) is among the most ubiquitously cultivated crops, very little is known about its origins. Here, we report discoveries of charred faba beans from three adjacent Neolithic sites in the lower Galilee region, in the southern Levant, that offer new insights into the early history of this species. Biometric measurements, radiocarbon dating and stable carbon isotope analyses of the archaeological remains, supported by experiments on modern material, date the earliest farming of this crop to ~10,200 cal BP. The large quantity of faba beans found in these adjacent sites indicates intensive production of faba beans in the region that can only have been achieved by planting non-dormant seeds. Selection of mutant-non-dormant stock suggests that the domestication of the crop occurred as early as the 11th millennium cal BP. Plant domestication| Vicia faba L.| Pre-Pottery Neolithic B| radiocarbon dating| Δ13C analysis.

Geoarchaeological Investigation in a Domestic Iron Age Quarter, Tel Megiddo, Israel

During the ongoing excavations of Area Q at Tel Megiddo, a variety of on-site geoarchaeological analytical methods have been used in the study of Iron Age occupations dating to the Iron Age IIA. The aim of this approach is to optimally combine macroarchaeology with microarchaeology in order to reconstruct activities that were carried out within an Iron Age urban neighborhood. The macroscopic finds indicate that this area belonged to a quarter that features both domestic and public structures. Of particular interest are (a) evidence for abandonment and spatial differentiation of activities in Level Q-5 associated with a large, well-built structure with 18 pillars; and (b) localized small-scale destruction associated with ephemeral metalworking activity related to occupation during Level Q-4. Similar approaches have been carried out at other sites in Israel (e.g., Tel Dor and Tell eṣ-Ṣâfi/Gath), yet only at Megiddo have we been able to use these methods to study a large excavation area (ca. 200 m2). The results shed new light on the variability of human activities in public and domestic contexts in an urban environment, and contribute to understanding the uses of space and the phenomenon of destruction by fire.

Radiocarbon Concentrations of Wood Ash Calcite: Potential for Dating

Ash is formed when plant calcium oxalate crystals (CaC2O4) decompose to form calcite (CaCO3). We found that ash does retain the original calcium oxalate radiocarbon concentration, but in addition, there is another minor 14C source. This is shown by the presence of a consistent small shift in the pMC and δ13C levels when comparing cellulose and ash from modern and archaeological woods. Possible mechanisms for 14C exchange during combustion or due to diagenesis are considered in order to define parameters for identifying better-preserved wood ash samples.

Structural differences in archaeologically relevant calcite

We show that two different sources of calcite (geogenic flowstones and anthropogenic lime plaster) have complex, yet distinctive, structural disorder signatures. It is effective to identify these differences by pairing a rapid, fieldwork-compatible technique (Fourier transform infrared (FTIR) spectroscopy) with a robust laboratory-based technique (X-ray diffraction (XRD) peak width analyses). We demonstrate that crystalline domain size, microstrain fluctuations, and lattice strain each affect the FTIR spectra of calcite. To focus on each variable separately, XRD data and FTIR absorption spectra are compared among calcite samples formed by different processes. Small crystalline domain sizes cause changes to FTIR peak intensity ratios (grinding curves). However, larger microstrain fluctuations or larger lattice strain also produce similar changes. Thus, inferring structural differences from calcite FTIR spectra alone is not advisable. Instead, we advocate using FTIR grinding curves in conjunction with analyses of angle-dependent XRD peak widths using the Williamson–Hall relation. Thus, combining these two analysis techniques is more powerful and informative than using either one alone. These findings are relevant for heritage science, including archaeology.

D-REAMS: A New Compact AMS System for Radiocarbon Measurements at the Weizmann Institute of Science, Rehovot, Israel

The Dangoor REsearch Accelerator Mass Spectrometer (D-REAMS) is a dedicated carbon-only AMS system, built by National Electrostatics Corporation (NEC). It is based on the 1.5SDH Pelletron, operating at 460 keV. The machine was installed at the Weizmann Institute of Science, Rehovot, Israel, in January–February 2013, and passed the acceptance test on March 2013. Since then, over 4500 samples have been successfully measured. Here, we present the results of an intercomparison experiment, done in collaboration with the Vienna Environmental Research Accelerator (VERA), and some typical operation parameters and measurement values of the new AMS system.

Radiocarbon chronology of Manot Cave, Israel and Upper Paleolithic dispersals

Manot Cave radiocarbon dates establish Levantine chronology, which is critical for understanding Upper Paleolithic dispersals. The timing of archeological industries in the Levant is central for understanding the spread of modern humans with Upper Paleolithic traditions. We report a high-resolution radiocarbon chronology for Early Upper Paleolithic industries (Early Ahmarian and Levantine Aurignacian) from the newly excavated site of Manot Cave, Israel. The dates confirm that the Early Ahmarian industry was present by 46,000 calibrated years before the present (cal BP), and the Levantine Aurignacian occurred at least between 38,000 and 34,000 cal BP. This timing is consistent with proposed migrations or technological diffusions between the Near East and Europe. Specifically, the Ahmarian could have led to the development of the Protoaurignacian in Europe, and the Aurignacian in Europe could have spread back to the Near East as the Levantine Aurignacian.

Accurate Radiocarbon Dating of Archaeological Ash Using Pyrogenic Aragonite

Obtaining accurate age determinations from minerals in archaeological ash is a major unsolved issue in radiocarbon (14C) dating. This is because the original 14C content of calcite, the main component of ash, is altered by isotopic exchange. Pyrogenic aragonite, another mineral phase recently discovered in ash, might preserve its 14C signature through time. Using a new method based on density separation and step combustion, we were able to isolate and date aragonitic ash from an archaeological destruction horizon of known age. Here we show that the 14C age of aragonite matches the age of the destruction horizon. Our results demonstrate that pyrogenic aragonite is a short-lived material suitable for 14C dating and directly related to human activities involving the use of fire, thus bearing major implications for the establishment of absolute chronologies for the past 50,000 yr.

Identifying a Roman Casting Pit at Tel Dor, Israel: Integrating Field and Laboratory Research

Abstract The functional identification of industrial features is difficult when few characteristic artifacts are preserved. We studied a Roman-period pyrotechnological feature at Tel Dor, Israel, where the only possibly diagnostic ceramic artifacts were found in fill between the walls and above the floor, rendering their association with the feature itself uncertain. The ceramic artifacts included coarse slabs and fragments of utilitarian vessels, some vitrified with adhering bronze droplets or slag-like residues. Analysis of the sediments within and around the industrial feature, using an X-ray fluorescence spectrometer on-site, revealed high concentrations of copper and lead, indicating metallurgical activity. Lead isotope analyses showed that the slag-like residue adhering to a ceramic fragment had the same isotopic values as the sediments, implying that the fragment was associated with the activities carried out in the feature. Microscopic and chemical analyses of the slag-like residue demonstrated that it was produced from melting leaded bronze. Some of the ceramic fragments contained elongated impressions on their inner surfaces, similar to those of casting molds found at other sites. We propose that the feature was used as a casting pit for bronze objects.

Early Bronze Age Pottery Covered with Lime-Plaster: Technological Observations

With the emergence of urban culture in the southern Levant in the Early Bronze Age, new types of pottery and ceramic techniques appeared, among them pottery (usually combed) coated with a white material. A selection of sherds from Early Bronze strata was studied in an attempt to analyze this material. Using microscopy and various other methods, the authors were able to determine that the white material was a lime-plaster applied to the vessels after firing. The paper contends that the most likely reason for applying the lime-plaster was functional—to decrease permeability and protect the contents of the vessels.