Employing Tl Methods for the Verification of Macroscopically Determined Heat Alteration of Flint Artefacts From Palaeolithic Contexts

Abstract

The reconstruction of past human use of fire is often based on the presence of fire in archaeological sites as evidenced by alterations of lithic material. Here, a simple test based on thermoluminescence (TL) methods is used as a verification tool for the macroscopic identification of burning damage on flint microartefacts from the Early and early Middle Pleistocene site of Gesher Benot Ya'aqov (Israel). The small dimensions of the microartefacts often prevented the removal of the outer surface, for which the TL signal might have been altered (bleached) by exposure to light during excavation. Bleaching of the TL signal by sunlight was found for fresh raw material, but appeared to be less problematic for the archaeological material, presumably due to patination. However, TL results for some samples are ambiguous and it is sometimes difficult to distinguish heating from post-depositional bleaching, especially for samples that are macroscopically considered as not having been heated. A qualitative interpretation of the TL data is compared with the macroscopic assessment. The general agreement of the TL analyses with the macroscopic observations provides an independent verification of the observed burning and thus supports the assumption that fire was used and controlled throughout the long occupational sequence of Gesher Benot Ya'aqov.

Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa

“…Some of the most intensive research on early use of fire has focused on the site of Gesher Benot Ya'akov in the Jordan Valley (Israel), dated to between 0.7 and 0.8 Ma, where pot-lid fractures, characteristic rounded concave scars produced by heat-induced removal of planoconvex flakes, have been used to identify burned microdebitage (14). Thermoluminescence analysis supports the identification of burned microdebitage, and its spatial distribution, together with the presence of charred wood, seeds, and grains led to the identification of "phantom hearths" (5,15,16). Nevertheless, the evidence and acceptance for controlled use of fire at any of the Acheulean sites noted earlier remains controversial.…”

Fires at Neumark-Nord 2, Germany: An analysis of fire proxies from a Last Interglacial Middle Palaeolithic basin site

“…Macroscopically observable alterations on lithic artifacts, as documented for the Neumark-Nord 2 assemblage, are indicative of heating temperatures of at least 300-350°C (Sergant et al 2006;Richter 2007;Richter et al 2011), which is confirmed for the pieces submitted to a TL heating plateau test (Richter and Krbetschek 2014). Thermal fracture, as observed on many of the studied pieces, has been shown to take place when the material is exposed to temperatures in excess of 400°C (Purdy and Brooks 1971;Domanski et al 1994;Domanski and Webb 1992;Buenger 2003).…”

Combustion at the late Early Pleistocene site of Cueva Negra del Estrecho del Río Quípar (Murcia, Spain)

“…Fire characterises the ‘Acheulean’ Gesher Benot Ya'akov site at the onset of the Brunhes chron, c. 078 Ma (Goren-Inbar et al 2004; Alperson-Afil & Goren-Inbar 2010; Richter et al . 2011; Alperson-Afil 2012). Barely 140km south-west of CNERQ, magnetostratigraphy identified the “Matuyama-Brunhes boundary only a few metres below the fossil/tool-bearing levels” (Scott & Gibert 2009: 82) at the open Solana del Zamborino site, where excavation uncovered five stones surrounding a possible hearth area containing carbonised wood (“madera carbonizada”, Botella López et al .…”

“…2012, who do not exempt Gesher Benot Ya'akov in that regard, contra Richter et al . 2011; Alperson-Afil 2012). At Swartkrans Cave, evidence of combustion (Skinner et al .…”