Victoria: The Nepean Ocean Coast (Point Nepean to West Head)

Introduction

The Nepean Peninsula consists of dune topography, with Pleistocene dune calcarenites overlain by unconsolidated Holocene dunes along the seaward fringe (Bird 1982). The Pleistocene and Holocene dune formations consist mainly of calcareous sand, with varying proportions (usually less than 20%) of quartz. The sand is biogenic, containing shell fragments and marine organisms that have come from the continental shelf, where similar sediment are forming at the present time. A borehole drilled at Sorrento in 1910 showed that dune calcarenites extend at least 140 m below sea level, with interbedded layers of marine sediment, including shelly beach sands and marine clays of the kind that are now accumulating on the floor of Port Phillip Bay. The rock sequence indicates several phases of dune sand accumulation interrupted by marine submergence and deposition during the intermittent subsidence of the country to the west of Selwyn Fault, which runs across to Cape Schanck, a...