Geology

The dunes have important conservation values as geomorphological features that are significant in their own right and contain considerable information about changes in coastal environments. Dunes are naturally unstable landforms and the dynamic dune processes should be allowed to continue without human interference.

The Barwon coastline is of varying age with the Barwon Bluff said to be around 125,000 years of age and the Ocean Grove Spit only being 6,000 years old. Our beaches are classed as intermediate of fine to medium sand, formed by moderate and low energy waves of 0.5 to 2.5 metres.

The Bluff is a ridge of Aeolian calcarenite; wind-blown limestone sand. The intertidal rock platforms consist of basalt and limestone. The basalt was deposited from the Mount Duneed volcano millions of years ago. The Bluff is of great geomorphological significance in representing the outlet of the Barwon River drainage system. The Bluff has weathered by time and tide with its ancient sand dune perched on a much older basalt base.

The Ocean Grove Spit is unique in providing access to both the river and the sea. It is a narrow point of land extending into the water.

Rockpools along the coast are exposed at low tide and are important homes to many smaller marine creatures, one being the Blue-ringed Octopus.  This shy creature prefers to be left alone, only showing its bright blue rings when becoming angry and is a warning that it may bite. Blue-ringed Octopus are highly poisonous. Stay safe along our coast – look but do not touch and keep fingers out of small dark places.

Blue-ringed Octopus video.

Barwon Bluff Marine Sanctuary video.

Barwon Bluff Living on the Edge video.