Did Port Phillip Bay nearly dry up between ~2800 and 1000 cal. yr BP? Bay floor channelling evidence, seismic and core dating

Abstract

Imagery of meandering river-like channel features up to 5 m deep and 100 m wide on the floor of Port Phillip Bay have been revealed by recent multibeam surveys. They are in water depths to -22 m below the present bay water level. This young channelling overlies older infilled Pleistocene-early Holocene channels considered to be cut by the Yarra and Werribee rivers during the last glacial or previous low stand minima > 10 000 cal. yr BP and infilled during the Holocene transgression. Vibrocoring data indicate the young channels incise shelly mud. Twelve 14C shell dates in vibrocores from bay floor to 3.5 m are in two units-a lower unit range between 2880 cal. yr BP at 0.7 m to 9491 cal. yr BP..