COASTAL LANDFORMS - Twelve Apostles

Question 1

Where are the Twelve Apostles?

Answer 1

• Port Campbell National Park, Victoria, Australia.
• Twelve Apostles Marine Park covers 17km of the coastline.

Question 2

What are the Twelve Apostles?

Answer 2

• Off a limestone cliff.
• Has steep cliffs (70m high), wave-cut platforms, notches, arches and stacks
• Steep slopes due to undercutting.
• Collection of stacks were originally called ‘Sow and Piglets’. They were changed in 1950s by Victorian tourists to be ‘12 Apostles’, even though only 9 were left.
• Attract tourists because they are in close proximity to each other. Also have boardwalks. tracks and viewing areas. Attract 1.7 million tourists a year.

Question 3

Have there been any recent changes?

Answer 3

• Cliff base constantly eroded by waves.
• Many stacks collapsed over time due to erosion.
• In May 2007, a 50m stack collapsed into a 10m pile of rubble.
• There are now only 8/12 Apostles standing.

Question 4

Why are there changes?

Answer 4

• Undercutting causes cliff to collapse along vertical joints.
• Erosion happens via hydraulic action, abrasion and corrosion, along bedding planes.
• Rate of erosion at base is 2cm per year.

Question 5

How did they form?

Answer 5

• Formed as horizontal beds of sediment and fossilised sea creatures over 10 million years ago.
• Twelve Apostles formed due to varying levels of erosion due to alternate bands of soft/hard rock.
• The protruding headlands formed where rock is hard, bays formed where soft.
• Erosion happens most at lines of weakness.
• Eventually, erosion causes caves to extend backwards into arches, where back wall is removed.
• When the arch collapses, stack is formed.
• Eroded into stump in future.

Question 6

What are they made of?

Answer 6

• Limestone