EARLY PLEISTOCENE STRATIGRAPHY AND TIMING OF THE BULGOBAC GLACIATION,WESTERN TASMANIA, AUSTRALIA

The Pieman River drainage basin, northwest Tasmania, preserves the mos t complete record of Cenozoic glacial advances from Australia although precise age control is mostly lacking. At least four pre-last Intergl acial glaciations can be recognised. Magnetostratigraphic evidence dem onstrates that the minimum age of the glacial diamictons (Bulgobac For mation) deposited during the most extensive glacial event, the Bulgoba c Glaciation, is early Pleistocene in age (>0.783 m.y.) based on rever sed-polarity recorded in associated glaciolacustrine sediments. The ma ximum age of this glaciation is >0.89 m.y. to latest Pliocene, based o n the palynology and magnetostratigraphy of silts (Marionoak Formation ) underlying the Bulgobac Formation at a site on the Huskisson-Mariono ak River divide. Plant macrofossils, spores and pollen suggest that cl imates at the time of deposition of the Marionoak Formation silts were drier than at present and cool, but not stadial or glacial in severit y.