In August 1973 a number of different types of shell bed were observed at Rottnest Island. The most massive of these were seen around the lakes at the eastern end of the island and there is no doubt that these are natural marine shell beds. However elsewhere shelly deposits were seen whose origin we could not determine with certainty. A number of midden like lenses of shell were exposed in road sections, particularly along the north side of the island. All of these deposits displayed some of the characteristics of Aboriginal shell middens.