Comparison of Thermoluminescence and Radiocarbon Age-Determinations from Late-Pleistocene Alluvial Deposits Near Sydney, Australia

Abstract

Radiocarbon and thermoluminescence (TL) age-determinations have been obtained for a large Pleistocene alluvial terrace on the Nepean River near Sydney, New South Wales, Australia. The deposit was laid down by a braided river system prior to the last glacial maximum. Six thoroughly pretreated samples of charcoal and degraded wood buried within gravels at the base of the terrace yielded apparent ¹⁴C ages of ∼37,000–42,000 yr B.P. These compare favorably with four TL determinations that gave apparent ages of ∼41,000–47,000 yr B.P. for the same deposit. Adjustment of the ¹⁴C ages to take geomagnetic effects into account further improves the correlation between these two independent dating techniques. In addition, ¹⁴C and TL correctly identified a reworked portion of the fine-grained alluvial overburden as being substantially younger than the main body of the terrace. These results augur well for the usefulness of TL age determinations of certain alluvial deposits.