Their proximity to one another has made the site a popular tourist attraction. Eight of the original nine stacks remain standing at the Twelve Apostles' viewpoint, after one collapsed in July 2005.[2] Though the view from the promontory by the Twelve Apostles never included twelve stacks, additional stacks—not considered part of the Apostles group—are located to the west within the national park.[3]
Formation and history
The limestone unit that forms The Twelve Apostles is referred to as the Port Campbell Limestone, which was deposited in the Mid-Late Miocene, around 15 to 5 million years ago.[4]
The Twelve Apostles were formed by erosion. The harsh and extreme weather conditions from the Southern Ocean gradually erode the soft limestone to form caves in the cliffs, which then become arches that eventually collapse, leaving rock stacks up to 50 m (160 ft) high. The stacks are susceptible to further erosion from waves. In July 2005, a 50-metre-tall (160 ft) stack collapsed, leaving eight standing at the Twelve Apostles' viewpoint.[2] Due to wave action eroding the cliffs, existing headlands are expected to become new limestone stacks in the future.[5]
The stacks were originally known as the Pinnacles, and the Sow and Pigs (or Sow and Piglets, with Muttonbird Island being the Sow and the smaller rock stacks being the Piglets), as well as the Twelve Apostles.[2][6] The formation's name was made official as the Twelve Apostles, after the Apostles of Jesus, to attract more tourists,[7] despite only ever having had nine stacks.[2]
In 2002, the Port Campbell Professional Fishermen's Association attempted to block the creation of the Twelve Apostles Marine National Park at the Twelve Apostles site.[8] The association approved of a later decision by the Victorian government to prohibit seismic exploration at the site by Benaris Energy,[9] believing such exploration would harm marine life.[10]
