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.