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 Twelve Apostles -
Port Campbell Coast
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This is the Matthew Flinders
Coastal Landform Site
Part of Flinders 2002 Web


The 'Investigator'

 SOUND

 naval whistle

Site:  Twelve Apostles - Port Campbell Coast  (Vic)


   LANDFORM THEME:  Features eroded from limestone cliffs

The Twelves Apostles, sea stacks, are the best known of many features along the cliffs of the coastline of western Victoria. Also carved out of the limestone plateau are numerous other features, including bridges, arches and gorges. In geological terms these features are not particularly long-lasting; the coast is retreating (moving landwards) in response to marine attack at its base. Waves of high average energy strike this coastline.  


   FLINDERS THEME:  Sailing close to a dangerous coastline

    Sailing eastwards along the southern coast (of what is now known as Victoria), the weather made it difficult for Matthew Flinders and the crew of the Investigator to maintain their customary high standards of observation. They were wary of the coastline here, which they could only glimpse between breaks in the clouds. Unknowingly, they sailed very close to a rock that was capable of destroying the ship. Captain Flinders was wise to be careful of the 'bold' coastline passed on a squally night. Many sailing ships were later lost along what is now called 'Shipwreck Coast'.


   Risky night run along the coast

   Comment on chart  The chart shows a night time run parallel to the coast under 'thick squalls'. Note the direction of the wind (south-west), tending to push the ship towards the coast. Had a major headland or rock suddenly appeared before the ship, the Investigator would have had limited ability to manoeuvre under conditions at that time.

Parts of the coast are missing from the chart; the Captain had more important things to do at this time than run his usual survey! (As well, visibility was poor on this night). As time was running short to reach Sydney, Flinders did not have the option of moving out to sea at night, and waiting for morning to recommence the survey, as he was accustomed to doing when time permitted.



Port Campbell Coast, chart

Extract from Flinders' chart (South Coast, Sheet IV)



      Sailing conditions were poor for the crew of the Investigator; there was little visibility and a southerly gale. Heavy rain and swell made this part of the expedition risky. Glimpses were gained during the night of the dangerous cliffs passing by as the ship headed southeast.


   The Twelve Apostles, and other features of the coast near the sheltered inlet of Port Campbell, are famous and rugged landforms carved by the sea from the limestone cliffs of SW Victoria. Originally the rock layers formed as horizontal beds of calcite-rich sediment on the sea floor. This rock is thus called sedimentary. Much originated from shells that had accumulated on the sea floor. 

   

  'A bold projection ... Head seen
... in a moonlight interval of thick squalls.'
  - from Matthew Flinders' chart
Photo 1: Twelve Apostles Coastline, Victoria




  The cliffs of Loch Ard Gorge and the entire coastline of this area are composed mainly of horizontally bedded limestone, deposited when the area was under sea millions of years ago. More recently the rock was gently uplifted and exposed to marine erosion. There are few safe ways to approach the land from the sea, and offshore reefs can be dangerous. 

A large range of erosional coastal features is found here, including gorges, sea arches, island stacks, natural bridges, and blowholes.



Loch Ard Gorge

Photo 2:  Loch Ard Gorge



   The Loch Ard Gorge contains a number of sea caves and overhanging areas at seal level (between tide lavels and a little above high tide level). They have formed in the rock as a result of marine action at the cliff base. 

   Consider the difficulty of overnight survival here after a shipwreck. Perhaps a cave back from the shoreline could offer some protection. To walk for help in daylight, it would be necessary to safely climb the cliffs; at some beaches along the coastline this would not be possible.



Sea cave

Photo 3:  Features of Loch Ard Gorge




   Waves, and constant wetting and drying of salt spray, attack the rock, disrupting it both physically and chemically. Landform change is brought about through the accumulation of these forces acting over time; the hydraulic pressure of the water striking the rock face, assisted by abrasive force of particles carried by waves, and the chemical weakening of the rock. It is believed that in landform terms, the cliff faces here are being eaten away relatively rapidly.

In places marine erosion is from several different directions, causing islands to be carved from retreating cliff faces. Vertical columns remaining from these erosive processes (such as the Twelve Apostles) are called stacks. An island can be further attacked, forming a sea arch (Island Archway, as shown) or a bridge.



Sea arch

Photo 4:  Island Archway

 

 


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(photo button above: Some of the Apostles - looking west)

Twelve Apostles
MAP


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For further information

LANDFORM LINKS
Landscape Setting: Warrnambool to Princetown
Photos of Port Campbell National Park features
Development of:
Coastal stack        Coastal cliff        Bay
Erosion of Sea Stack Over 100 Years
Limestone (rock type of the Twelve Apostles)
Coastal Erosion in Limestone - The Apostles Area
Loch Ard Gorge short walks
Walks of the Great Ocean Road


ENVIRONMENTAL LINKS
Port Campbell National Park
Twelve Apostles Marine National Park
Twelve Apostles Web Site



Printed Materials

Morrison,R. - Australia: The Four Billion Year Journey of a Continent
Weldon Publishing, Frenchs Forest NSW. 1988

Clark, I.F. & Cook, B.J. - Geological Science: Perspectives of the Earth
Australian Academy of Science, Canberra ACT. 1983

Reader's Digest Guide to the Australian Coast
Reader's Digest Services, Surrey Hills NSW. 1983

Reader's Digest Scenic Wonders of Australia
 Reader's Digest, Surry Hills NSW. 1976

and  Matthew Flinders  Books



 


Site / Photos (c) C.Grant 2002, 2003