The 12 Apostles of Victoria, Australia

Flashcards covering key facts, geological composition, and the formation process of the 12 Apostles in Victoria, Australia, based on lecture notes.

Where are the 12 Apostles located?

Victoria, Australia

What is the approximate height of the 12 Apostles stacks?

Up to 50m tall

Roughly how long ago were the 12 Apostles formed?

8-14 million years ago

How many limestone stacks are currently visible at the 12 Apostles coastline?

9

What type of rock primarily forms the 12 Apostles stacks?

Limestone

What rock type underlies the limestone of the 12 Apostles stacks?

Gellibrand Marl

How is Gellibrand Marl described?

A silty and muddy rock type

What significant event occurred in 2005 concerning the 12 Apostles stacks?

One of the 9 stacks collapsed into rubble

Approximately how long ago was the site of the 12 Apostles an expanded ocean with unusually high sea levels?

Around 15 million years ago

How high were sea levels above modern levels during the initial formation stage of the 12 Apostles?

Around 30 metres

What material was deposited over time, creating the base of the 12 Apostles and cliffs?

Large amounts of Marl

What environment was created when the sea level rose by another 30 metres after Marl deposition?

An unspoilt environment for coral reefs and ocean creatures

What substance precipitated to the ocean floor as corals and ocean creatures died, leading to the rapid buildup of limestone?

Calcium carbonate

For how many million years did limestone layers build up, eventually creating a 50-metre thick rock?

6 million years

After the limestone buildup, how much did the sea level decrease?

30 metres

What natural element caused large cracks to form in the limestone over time?

Slightly acidic rain

What type of erosion process, involving different rates, created the vertical pillars of the 12 Apostles?

Preferential erosion