Prior to the construction of the Inner Harbour in Fremantle in the closing years of the nineteenth century, the body of water that is now the Inner Harbour comprised a broad estuary, and the Swan River flowed in to the sea across a shallow rock bar between two rocky headlands.
The history of construction of the Inner Harbour is described to illustrate the complexity of the geology in this part of Fremantle. The geology includes a deep sediment filled palaeochannel associated with a former course of the Swan River during the Quaternary when the sea level was considerably lower than its current level. The construction of the harbour involved blasting of the rock bar, major dredging and land reclamation and extensive piling. The distribution and impact of the various geological units on the harbour and a number of the geotechnical issues that have lead to construction difficulties in the past are detailed.