All,
Here is something I forgot to mention earlier – I think! Worth taking into account, given the importance of Border Cave in the ongoing discourse regarding the early presence of so-called “modern man” in South Africa. Also interesting, to the extent that the authors state, unequivocally, that, with appropriate samples and the use of what is called the “ABOX-SC technique”, they can get very close to the limits of what C14 can tell us about the age of things.
If you do not have access to the primary literature, and if you want to know more about the “ABOX-SC technique” and how reliable it might be, try an “ABOX-SC” Google search. And, perhaps, with luck some Radiocarbon aficionado will feel compelled to convincingly tell us all about it!
Jacques Cinq-Mars
Bird, M. I. (a), L. K. Fifield (b), G. M. Santos (b), P. B. Beaumont (c), Y. Zhou (a), M. L. di Tada (b) and P. A. Hausladen (b). 2003. Radiocarbon dating from 40 to 60 ka BP at Border Cave, South Africa. Quaternary Science Reviews 22(8-9): 943-947.
a Research School of Earth Sciences and Research School of Biological Sciences, Australian National University, Canberra, A.C.T. 0200, Australia
b Department of Nuclear Physics, Research School of Physical Sciences and Engineering, Australian National University, Canberra, A.C.T. 0200, Australia
c McGregor Museum, Kimberley, South Africa
Abstract:
We present 21 radiocarbon dates on 19 charcoal samples from the sedimentary sequence preserved in Border Cave, South Africa. The background radiocarbon activity for charcoal from the cave was determined to be 0.050±0.018 percent modern carbon, from the analysis of a radiocarbon-dead sample from unit 5WA. Radiocarbon ages for individual samples ranged from 25.2 to >58.2 ka BP.
The error-weighted mean ages for successively older strata are 38.5+0.85/-0.95 ka BP for unit 1WA, 50.2+1.1/-1.0 ka BP for units 2BS.LR.A and 2BS.LR.B, 56.5+2.7/-2.0 ka BP for unit 2BS.LR.C and 59.2+3.4/-2.4 ka BP for unit 2WA. This radiocarbon chronology is consistent with independent chronologies derived from electron spin resonance and amino acid racemization dating. The results therefore provide further evidence that radiocarbon dating of charcoal by the ABOX-SC technique can yield reliable radiocarbon ages beyond 40 ka BP. They also imply that Border Cave 5, a modern human mandible, predates >58.2 ka BP and that the Middle Stone Age (Mode 3)––Later Stone Age (Mode 5) transition of Border Cave was largely effected between ~56.5 and ~41.6 ka ago.
Copyright © 2003 Elsevier Science Ltd. All rights reserved.
