Quaternary studies of caves and coasts : a collection of published papers and a critical review

The contents of this volume are not a PhD thesis in the conventional sense in that they do not represent a single major research theme. When the author approached the Higher Degree Committee of the University of Tasmania with the view of counting twenty-nine published papers towards a higher degree, he was instructed to enrol for a research higher degree (PhD), and to present a thesis not only containing the publications but critically reviewing them in the form of a thesis to be completed over a period of not less than one year. The thesis thus comprises a review of twenty-nine published papers on a common theme of \Quaternary Studies of Caves and Coasts\". Most papers are concerned with aspects of cave sediments but some are focussed on the sedimentary history of coasts. For the sake of completeness it was found necessary to include one paper submitted for publication but not yet published as well as some unpublished data. Studies of caves commenced with an investigation of bone-rich deposits many of which contained remains of Pleistocene megafauna. The thesis concentrates on aspects of stratigraphy dating and interpretation of depositional environments. Discovery of an archaeological site led to the realisation that interior valleys of Tasmania had been colonised by aborigines during the Last Glacial. Later studies concentrated on the use of speleothems as an information source on past climates and environments and used analysis of stable isotope ratios and minor element concentrations to study temporal variations. The study commenced with a detailed analysis of the isotopic composition of precipitation and seepage waters - a vital prerequisite. Oxygen isotope composition of Tasmanian speleothems was found to be not directly controlled by temperature but by the isotopic composition of winter precipitation. It is best interpreted as a proxy for mean winter temperature. Carbon isotope variations are regarded as due predominantly to variations in plant productivity and appear to be partly controlled by the precessional cycle. Studies of minor element variations were focussed on magnesium and strontium with preliminary investigation of uranium and bromine. Strontium isotope analysis was used to show that some of the strontium was derived from a non-limestone source - probably wind-borne dust derived from continental shelf areas when sealevels were low. The magnitude of the dating peak (h3) in electron spin resonance spectra was found to be strongly correlated with carbon isotope ratios and concentrations of uranium magnesium and bromine. The signal has considerable potential as an indicator of changes in vegetation productivity and/or fire frequency. Coastal studies commenced with electron spin resonance analysis of marine gastropod shell from midden sites in sea caves at Klasies River Mouth South Africa where the technique was developed as a relative dating method in good agreement with the cultural and stratigraphic sequence of the sites. Use of the method continued on coastal deposits in western Victoria Tasmania and the Bass Strait Islands where it was calibrated against other dating methods especially amino acid racemisation dating. The Bass Strait study revealed that King and Flinders Islands had been tectonically uplifted during the Quaternary as was Tasmania but uplift began earlier and had ceased 125000 years ago. Age determination is a vital part of Quaternary studies and is reviewed in a separate chapter. Improvements in dating techniques and calibration during the review period are discussed and earlier age estimates have been updated."