ABSTRACT
The Yarra Delta, situated at the head of Port Phillip Bay, is an area of Quaternary sedimentation with an intercalated flow of basalt in its eastern part. This chapter describes the geological constitution of the Yarra Delta and its evolution in a way that relates to the needs of engineering. The Quaternary geological units which together comprise the Yarra Delta rest on an undulating plane inclined to the south-west at a low angle, which is a terrain of both steeply dipping Silurian mudstone and sandstone and gently south-westerly dipping Tertiary formations. The surface on which the Quaternary geological units which comprise the Yarra Delta rest is of basal Quaternary age. Yarra Delta and are found throughout its extent though not without gaps in occurrence. Man has had a profound effect upon the Yarra Delta. Across most of it, bores and excavations usually encounter filling immediately below the surface before the sedimentary materials of the Yarra Delta are reached.
