TL dating of burnt lithics from Blombos Cave (South Africa)

African Heritage Research Institute, 167 Buitenkant Street, Gardens, 8001, Cape Town, South Africa
Archaeometry (Impact Factor: 1.52). 04/2006; 48(2):341 - 357. DOI: 10.1111/j.1475-4754.2006.00260.x


This paper presents the first TL dates for burnt quartzites and silcretes from the Still Bay layers of Blombos Cave (South Africa). These layers contained engraved ochres and marine shell beads that could be an early manifestation of symbolic and thus ‘modern’ behaviour by the Middle Stone Age humans. The procedure devised to calculate the ages is presented in detail, particularly with regard to internal microdosimetry, because the problems faced in estimating the dose rates require an approach different from the one usually used on flints and sediments. A mean age of 74 ± 5 ka was obtained for five burnt lithics unearthed in the BBC M1 member of the Still Bay layers. This result is in good agreement with both ESR dates on teeth and OSL dates on sediment, and demonstrates the great antiquity of the archaeological remains discovered at Blombos Cave.

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Available from: Christopher S Henshilwood, Aug 19, 2014
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    • "R . G . Roberts et al . / Journal of Archaeological Science 56 ( 2015 ) 41e60 51 Tribolo et al . , 2006"
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    ABSTRACT: In 1982, when Richard Klein first became one of the Editors of this journal, the luminescence dating community was embarking on a new phase of exploratory research. Attention was turning from the use of thermoluminescence (TL) dating to estimate the time of last heating of archaeological objects, such as pottery and burnt flint, to the TL dating of unheated sediments that had been transported by wind and then deposited on the landscape. This revolutionary development enabled the extension of TL dating to sedimentary deposits in a variety of environmental settings and to the multitude of archaeological sites that lack suitably heated artefacts. In sediment dating, the age of most interest is usually the time elapsed since grains of quartz or feldspar were last exposed to sunlight, as the energy of the sun's rays is sufficient to evict electrons from their light-sensitive traps. These traps are steadily refilled after sediment deposition and the longer the grains remain buried, the more TL they will emit when measured. In 1985, Huntley and colleagues proposed ‘optical dating’ as a simpler and superior means of stimulating the light-sensitive traps in Quaternary sediments, and this is now the principal luminescence-based method of dating geological and archaeological deposits. Optical dating is an umbrella term for an armada of acronyms, the most common in archaeological contexts being OSL (optically stimulated luminescence), TT-OSL (thermally-transferred OSL), IRSL (infrared stimulated luminescence) and pIRIR (post-infrared IRSL). All of these variants are founded on the same basic tenet – measurement of a light-sensitive signal to determine (typically) the last time that sediment grains were sun-bleached – but each approach has its virtues and vices. In this paper, we review this ‘family’ of luminescence dating techniques and look back on 30 years of optical dating in archaeology. Some of the more interesting and important achievements are highlighted, including the critical insights gained in the last two decades from OSL measurements of individual grains of quartz. We also look to the future of optical dating in archaeological contexts. Efforts to extend the age limits of optical dating to older hominin and archaeological sites will remain a key goal, and understanding how archaeological sites – of all ages – form and evolve over time could be improved greatly by combining micromorphology analysis with optical dating of undisturbed (intact) sediments. The latter poses a series of particularly formidable technical challenges, but if the past is any guide to the future, then we can expect optical dating to illuminate much more of human history before celebrating its Golden Jubilee.
    Full-text · Article · Apr 2015 · Journal of Archaeological Science
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    • "The M1 phase has an age of ∼73 ka (Jacobs et al. 2006) and the upper M2 has an age of ∼77 ka (Jacobs et al. 2006; Tribolo et al. 2006; Henshilwood et al. 2011). These two phases contain artefact types associated with the Still Bay techno-tradition. "
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    ABSTRACT: The ∼100 ka Middle Stone Age levels at Blombos Cave, southern Cape, South Africa, contain numerous rock hyrax (Procavia capensis) remains. It is often ambiguous to interpret rock hyrax remains from archaeological deposits deriving from cave and shelter sites in southern Africa as the agent or agents of accumulation may be difficult to establish. In this paper, the different taphonomic signatures separating anthropogenic from natural accumulations at Blombos Cave are considered. The analysis indicates that although a few specimens show evidence for raptor and carnivore accumulation, there is also substantial evidence that suggests humans preyed on these small mammals during different times of the year.
    Full-text · Article · Mar 2014 · African Archaeological Review
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    • "T L Tribolo et al . , 2006 81 AE"
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    ABSTRACT: The site of Blombos Cave (BBC), Western Cape, South Africa has been a strong contributor to establishing the antiquity of important aspects of modern human behaviour, such as early symbolism and technological complexity. However, many linkages between Middle Stone Age (MSA) behaviour and the subsistence record remain to be investigated. Understanding the contribution of small fauna such as tortoises to the human diet is necessary for identifying shifts in overall foraging strategies as well as the collecting and processing behaviour of individuals unable to participate in large-game hunting. This study uses published data to estimate the number of calories present in tortoises as well as ungulates of different body size classes common at South African sites. A single tortoise (Chersina angulata) provides approximately 3332 kJ (796 kcal) of calories in its edible tissues, which is between 20 and 30% of the daily energetic requirements for an active adult (estimated between 9360 kJ [3327 kcal] and 14,580 kJ [3485 kcal] per day). Because they are easy to process, this would have made tortoises a highly-ranked resource, but their slow growth and reproduction makes them susceptible to over-exploitation. Zooarchaeological abundance data show that during the ca. 75 ka (thousands of years) upper Still Bay M1 phase at BBC, tortoises contributed twice as many calories to the diet relative to ungulates than they did during the ca. 100 ka lower M3 phase. However, in spite of the abundance of their fossils, their absolute caloric contribution relative to ungulates remained modest in both phases. At the end of the site's MSA occupation history, human subsistence strategies shifted to emphasise high-return large hunted mammals, which likely precipitated changes in the social roles of hunters and gatherers during the Still Bay.
    Full-text · Article · Jan 2014 · Journal of Human Evolution
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