Evidence for a change in wind regime during the Last Glacial Maximum from the Sydney region

Abstract

This paper presents the results of a small number of dates from sand samples collected at building sites in the eastern suburbs of Sydney. OSL ages of well-sorted, quartz sand ranges from 31 to 24 ka from within well-developed podzol soil profiles within a metre of the surface. The source of this sand appears to be from the east off the inner continental shelf during a period just prior to the maximum of the Last Glacial Maximum (LGM, Marine Isotope Stage 2) when sea-level was approximately 70–90 m below present level. During a later phase of the LGM, there is evidence from other coastal sites in central NSW and Gippsland, Victoria, that the dominant wind was from the west consistent with evidence from arid and semiarid Australia. Dune orientations in northern NSW into Queensland and other evidence at this time appear to reflect winds from the southeast quadrant. This study highlights the existence of a potential pivot area in dominant wind direction during the LGM between sustained westerly flow in southern area including Victoria and northeast Tasmania and southeast flow of northern NSW into Queensland. In central NSW, the circulation switched from easterly in Stage 2 to westerly as the glacial stage intensified in the LGM sometime after ca 25 ka.

Key Words:

• Cliff-top dunes
• podzolised sands
• sand transport
• wind circulation patterns
• glacial low stand
• past sea-level

Acknowledgements

Laboratory support from members of the Luminescence Dating Facility at the University of Wollongong is greatly appreciated including Dr Zenobia Jacobs, Dr Terry Lachlan and Yasaman Jafari. We are grateful to David Price for preparing and measuring one sample for TL dating at the University of Wollongong.

Additional information

Funding

Funds to support sample dating were from Discovery Project Grant ID: DP150101936. Field assistance was provided by Michael Kinsela.