1. Research School of Earth Sciences, Australian National
University, Canberra, A.C.T. 0200, Australia
2. Department of Nuclear Physics, Research School of Physical
Sciences and Engineering, Australian National University, Canberra,
A.C.T. 0200, Australia
3. School of Earth Sciences, University of Melbourne, Melbourne, VIC
3010, Australia
4. People and Environment Section, National Museum of Australia,
Canberra, A.C.T. 2601, Australia
5. Anthropology Department, Western Australian Museum, Francis
Street, Perth, WA 6000, Australia
6. Australian Nuclear Science and Technology Organisation, PMB1,
Menai, NSW 2234, Australia
7. Institute of Arctic and Alpine Research and Department of
Geological Sciences, University of Colorado, Boulder, CO 80309-0450,
USA
8. Department of Geology and Geophysics, The University of Utah, 135
South, 1460 East, Salt Lake City, UT 84112, USA
9. Centre for Archaeology, University of Western Australia, Nedlands,
WA 6907, Australia
10. Land and Water Sciences, Bureau of Rural Sciences, P.O. Box E11,
A.C.T. 2604, Australia
*Present Address: Centre for Quaternary Research,
Geography Department, Royal Holloway, University of London, Egham,
Surrey, TW20 0EX, UK
There are currently two competing hypotheses concerning the time at which people arrived on the Australian continent. Conventional radiocarbon chronologies suggest arrival ~40,000 yr BP, while chronologies based largely on optical dating favor arrival by at least 50,000 yr. Here we report AMS-14C ages obtained by both an acid-base-acid pretreatment with bulk combustion (ABA-BC) and a newly developed acid-base-wet oxidation pretreatment with stepped combustion (ABOX-SC), applied to hand picked charcoal from the earliest occupation levels of the Devil's Lair site in southwest Western Australia. Initial occupation of this site has previously been dated by conventional 14C techniques to 35,000 yr BP. While the ABA-BC ages are indistinguishable from background beyond 42,000 yr BP, the ABOX-SC ages form a coherent 14C stratigraphy to ~55,000 yr BP. The ABOX-SC chronology suggests that people were in the area by at least 48,000 cal yr BP. Optically stimulated luminescence (OSL), electron spin resonance (ESR) ages, U-series and Emu eggshell carbonate 14C dating are in agreement with the ABOX-SC 14C chronology. These results, based on four independent techniques, reinforce arguments for an earlier colonization of the Australian continent.