The Twelve Apostles, Rock Formation In Australia is one of the important rock formation. The Twelve Apostles are huge pillars of limestone rock in the ocean offshore from the Port Campbell National Park, along the south-east coast of Australia. Formed by the sea eroding the cliffs, the stacks are of varying heights and thicknesses. There are now eight pillars, with the most recent collapse being that of a 50-m tall column which fell apart on July 3, 2005. However, more are expected to be formed as the cliffs continue to erode.