The bedrock topography and origin of Broken Bay, N.S.W.

Abstract

The bedrock topography of Broken Bay on the eastern coast of Australia has been investigated by means of a low‐power marine sparker system. It has been possible to reconstruct the upper Pleistocene drainage pattern, which differs somewhat from the present configuration of the estuary. Two distinct bedrock channels have been identified: the first along the present Hawkesbury River and the second along the present position of Pitt Water. They are separated by a rock bar across the entrance of Pitt Water. The Pitt Water channel has been identified as reaching the sea through the Palm Beach tombolo. Bedrock depths in the entrance of Broken Bay reach 125 m below sea level, which is consistent with the rise of sea level due to post‐glacial melting.