In order to gather information about the sub-seafloor depth to massive bedrock within Port Lincoln Harbour, needed as part of the process for designing proposed new wharves and ship berthing facilities to be built in the area between Main (Railway) Jetty and Kirton Point Jetty, a programme of shallow diamond drilling was carried out for the SA Harbours Board by the SA Department of Mines during the period May-June 1950. The initial requirement for siting the planned facilities stipulated a bedrock location beneath the seabed which lies beyond the 30 foot depth below Low Water Mark, but this minimum depth requirement for site position was later increased to minus 46 feet. To date 34 bores have been sunk at 50 foot intervals along 4 drilling traverses running out into the bay from the shore. The drillhole core samples were geologically logged, and a provisional contour map of the bedrock surface topography was drafted. It was recommended that more closely spaced drilling would be required to delineate this surface with any accuracy.