Geomorphic Processes

Erosion process. 
Cavern Formation.

 

  • 4 major caverns penetrate the headland’s 26 meter high cliffs. The Great Ocean Road was closed on the headland in 2003 due to the risk of the cavern collapse.
  • Limestone is prone to erosion from surface water, creating sink holes, swallow holes and caverns.
  • Once the joints in the limestone has been formed, groundwater furthur erodes along these lines and wave action mechanically enlarges the joints/caverns.

The caverns were formed by groundwater draining from the land along natural joint lines.

The groundwater contains atmospheric carbon dioxide to make carbonic acid which dissolves limestone.

Major joints occur in Port Campbell Limestone approx every 100 meters. Smaller joints and tunnels crisscross between major joints.

New caverns are opening up in the bay and joint lines appear to run through the proposed development site.
Diagram Courtesy of Dr Eric Bird.

For Further reading:

https://visit12apostles.com.au/natural-wonders/apostles-naming/

https://parkweb.vic.gov.au/learn/teacher-portal/learning-resources