A high-resolution record of vegetation and climate through the last glacial cycle from Caledonia Fen, southeastern highlands of Australia A. P. KERSHAW, 1 * G. M. MCKENZIE, 1 N. PORCH, 1y R. G. ROBERTS, 2 J. BROWN, 1 H. HEIJNIS, 3 M. L. ORR, 1 G. JACOBSEN 4 and P. R. NEWALL 1 1 Centre for Palynology and Palaeoecology, School of Geography and Environmental Science, Monash University, Victoria, Australia 2 GeoQuEST Research Centre, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, New South Wales, Australia 3 Sydney Catchment Authority, Penrith, New South Wales, Australia 4 Australian Nuclear Science and Technology Organisation, Menai, New South Wales, Australia Kershaw, A. P., McKenzie, G. M., Porch, N., Roberts, R. G., Brown, J., Heijnis, H., Orr, M. L., Jacobsen, G. and Newall, P. R. 2007. A high-resolution record of vegetation and climate through the last glacial cycle from Caledonia Fen, southeastern highlands of Australia. J. Quaternary Sci., Vol. 22 pp. 481–500. ISSN 0267-8179. Received 24 January 2007; Revised 20 February 2007; Accepted 27 February 2007 ABSTRACT: A blocked tributary has provided a rare site of long-term sediment accumulation in montane southeastern Australia. This site has yielded a continuous, detailed pollen record through the last ca. 140 000 years and revealed marked vegetation and environmental changes at orbital to sub-millennial scales. Radiocarbon and optically stimulated luminescence (OSL, or optical) ages provide some chronological control for the last ca. 70 000 years. Most of the sediment is inorganic but with well preserved pollen that accumulated under unproductive and probably largely ice-covered lake conditions. The lake was surrounded by low-growing plants with an alpine character. Exceptions include three discrete periods of high organic sedimentation in the basin and forest development in the surrounding catchment. The two major periods of forest expansion are related to the last interglacial and the Holocene, with the third, shorter period considered to represent an interstadial in the early part of Marine Isotope Stage (MIS) 3. The latter part of the last glacial period is characterised by abrupt sub-millennial, amelioration events that may relate to documented global oscillations emanating from the North Atlantic. There are systematic changes through the record that can be partly attributed to basin infilling but the progressive reduction and regional extinction of some plant taxa is attributed to a long-term trend towards climatic drying. Copyright # 2007 John Wiley & Sons, Ltd. KEYWORDS: late Quaternary; climate change and variability; vegetation dynamics; optical dating; southeastern Australia. Introduction Southeastern Australia has been a focus for palynological studies that cover at least the last glacial cycle, though a regional picture for comparison with other parts of the world has been difficult to establish. Lake George (Singh et al., 1981; Singh and Geissler, 1985) provides a general record through the Mid–Late Pleistocene and Holocene, but concerns over continuity of sediment deposition within this large tectonic lake system, variable pollen preservation and limitations of dating, have not allowed detailed comparison with other long terrestrial records or the marine isotope record. The volcanic crater setting of Lake Wangoom appears to provide clear pollen variation on the orbital timescale but uncertainty in the chronology, that has depended largely on uranium/thorium (U/Th) disequilibrium dating, has resulted in debate over whether one or two glacial cycles is represented (Harle et al., 1999, 2002; Kershaw and van der Kaars, 2007). Lake Selina, ‘outside LGM glacier limits’ in western Tasmania, provides evidence of vegetation changes within the most humid part of southeastern Australia (Colhoun et al., 1999, Colhoun, 2000). JOURNAL OF QUATERNARY SCIENCE (2007) 22(5) 481–500 Copyright ß 2007 John Wiley & Sons, Ltd. Published online in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/jqs.1127 * Correspondence to: Professor A. P. Kershaw, Centre for Palynology and Palaeoecology, School of Geography and Environmental Science, Monash University, VIC 3800, Australia. E-mail: peter.kershaw@arts.monash.edu.au y Present Address: Department of Archaeology and Natural History, Research School of Pacific and Asian Studies, The Australian National University, Canberra, ACT 0200, Australia. z Melbourne Corporation, GPO Box 261, Melbourne, VIC 3001, Australia.