Once upon a time, the Twelve Apostles – the huge rock stacks that stand offshore near Port Campbell in south-east Australia – were part of the jagged limestone cliffs. These stacks have resisted thousands of years of battering by relentless seas as the rock around them was slowly worn away. Now they stand alone, lonely markers of an earlier shoreline.
Huge waves continue to batter and reshape the cliffs, which stretch for nearly 20 miles (32km) and are a popular tourist spot. In 1990 a couple stood at the end of London Bridge – a natural pier jutting into the ocean, with two arches worn away by the action of the sea. As the couple prepared to take a photograph of the cliffs, the arch in front of them broke into pieces without warning and plunged into the sea, leaving them stranded. A police helicopter soon took them to safety, but 130ft (40m) of London Bridge, its link with the land, was gone forever. In July 2005, one of the stacks collapsed into the sea, Leaving in its place a pile of rocks.
All along the Port Campbell shore, a national park, rocky islets of various shapes – wedges, stacks, grottoes, chimneys, arches – rise starkly from the ocean. Jon them up like the dots in a giant puzzle, and the ghost of the now-vanished shoreline emerges. The Twelve Apostles and London Bridge, with neighbouring formations such as Sentinel Rock, Baker’s Oven and Thunder Cave, are links in this ancient chain.
The Port Campbell rock is limestone formed 26 million years ago when the whole area was under the sea. As marine animals died, millions of tiny skeletons rich in calcium accumulated on the seabed. Slowly they built up on an 850ft (260m) layer of limestone on top of the soft clay floor. About 20,000 years ago, during the last Ice Age, the sea level dropped and the rock was exposed.
Wind, rain and waves began to pummel the soft bluffs, and the constant assault of centuries has sent chunks of land crashing into the ocean every 20 or 30 years. In some places, the coastline has retreated uniformly, leaving no clues to its original shape, but in others weaker sections gave way first, creating the stacks and arches of today.
The Southern Ocean is whipped up here by strong winds known as the ‘Roaring Forties; huge storm waves may cut ledges in the limestone some 200ft (60m) above the high tide mark. Near Thunder Cave, The Blowhole illustrates how the sea exploits weaker beds in the rock to encroach on the land. Here the water thunders underground for 430yds (400m) along a wave-carved tunnel. Where the roof has caved in, visitors can peer down a ‘blowhole’ at the water churning below.
The scenic stacks bring a steady stream of tourists all year round. Birds such as the Tasmanian mutton bird (or short-tailed shearwater) cone here, too. They breed on the rocky outcrops of the largest stack, Mutton Bird Island, arriving in late September in their hundred of thousands after making a perilous 9000-mile (14,400km) journey across the Pacific Ocean from Siberia.
Nesting burrows are jammed side by side into every available crevice on the island. Here the birds can raise their chicks in peace, secure on the heights from predators such as rats and men.
Many other birds – albatrosses, gannets, Cormorants and petrels – also come to feast on the rich supply of fish. Southern right whales pass by in winter, on the way from Antarctica to their breeding grounds off the Great Australian Bight – a few stops to breed here. But most of them pass by close to the shore, untroubled by the turbulent sea and its ruined rocks.