At Hallett Cove, evidence of episodes of the earth’s history from the last 600 million years can be seen, from a total earth age of about 4,600 million years.

Much of the evidence has been eroded from the Hallett Cove landscape and lost from the geological record. However, some results of the earth’s continuous geological change remain for us to see and piece together.

The following brief summary of these ongoing and complex events has been sourced from The Field Guide to the Geology of Hallett Cove and A Field Guide to the Coastal Geology of Fleurieu Peninsula, both produced by the Field Geology Club and available through their website:

Precambrian limestone stromatolites. These large rocks can be found on the shoreline.
They have been formed by the growth of blue-green algae in hummock shaped layers.
The fossilised structures are the remains of microbial reefs.

Evidence of geological phenomena To be observed at Hallett Cove

Alluvial Sediments
Anticlinal Fold
Chatter Marks
Climate Change

Fossiliferous Sandstone
Glacial Striations
Graded Bedding
Ice Age Evidence

Permian Sediments
Proterozoic Sediments
Ripple Marks

Shoreline Platform
Striated Pavements

U-Shaped Valley
Wave Cut Platform

While preserving the unique geological evidence at Hallett Cove is the Park’s primary purpose, there are other important environmental aspects to be conserved and explored.

The Park has the largest area of publicly accessible remnant coastal vegetation along the metropolitan coastline and it is a sanctuary for birds, reptiles and insects.

Disturbance or removal of rocks, fossils or biological specimens is not allowed

Further reading

Overview of Hallett Cove Geological History, by Mark Willoughby, 6 Jul 2010.  

Giesecke, R (Ed., 1999): A Field Guide to the Geology of Hallett Cove and other Localities with Glacial Geology on the Fleurieu Peninsula (1999),

Hasenohr, P. & Corbett, D. (Eds., 1986) A Field Guide to the coastal Geology of Fleurieu Peninsula,, Adelaide.

Hallett Cove Conservation Park Management Plan (Amended 2017) Management Plan 2017

Geological Map of Hallett Cove (good article for geologists/students) at PIRSA