Optical dating of dune sand from Blombos Cave, South Africa: I - multiple grain data

Type Article
Original languageEnglish
Pages (from-to)599-612
Number of pages14
JournalJournal of Human Evolution
Volume44
Issue number5
DOI
Publication statusPublished - May 2003
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Abstract

An aeolian sand unit overlies the Middle Stone Age deposits at Blombos Cave on the southern Cape coast. These deposits contained culturally-important artefacts, including bone tools and pieces of engraved ochre, as well as a large number of worked lithics. The aeolian sand and two other remnants of the sand dune formed against the coastal cliff were dated using optical dating. To determine the dose received since deposition, measurements were made on 5 mg aliquots of purified quartz grains using the single-aliquot regenerative-dose (SAR) protocol. The results of several internal check procedures are reported and at least 15 replicate dose determinations are presented for each sample. Combining these dose values with measurements of the radioactive content of each sample resulted in an age of 69.2±3.9 ka for the unit within the cave, and a mean age of 70.1±1.9 ka for all three dune samples. This provides a minimum age for the Middle Stone Age material at Blombos Cave.

Keywords

  • optical dating, Single Aliquot Regeneration (SAR), Blombus Cave, middle Stone Age, Aeolian sediment