Coastal Plain and Port Campbell National Park

The coastal plain of the western district of Victoria in Australia ends abruptly and rather spectacularly at the coast in the form of vertical limestone cliffs. Many rugged and extraordinary landforms have been eroded into the limestone by the unrelenting, battering force of the Southern Ocean, a process facilitated by the soluble nature of the limestone.

About 1750 hectares of the coast between Princetown and Peterborough form the Port Campbell National Park, which includes many of the more interesting features.

One erosion cycle begins with the waves attacking a line of weakness at the base of the cliff to form a cave. Continual undercutting by the waves sometimes leads to the formation of a tunnel. When there is a weakness in the earth above a tunnel and it collapses, a blowhole is formed. Within the Port Campbell National Park there is a spectacular blowhole where the sea surges underground for 100 metres and erupts through a huge hole, 17 metres deep and 40 metres wide.

A development from the blowhole occurs when the tunnel collapses, forming a narrow ravine or canyon. Loch Ard Gorge, in the park, was originally formed in this way, but erosion of the cliffs along its sides is continually widening the canyon. At the head of this canyon the effects of water percolating through the limestone can be seen in the form of stalactites, as in limestone caves.

Probably the most striking of the Port Campbell landforms are various rock stacks and arches. As the waves attack the sides of a headland jutting into the ocean; they gradually carve caves, which in turn are progressively eroded through to form a natural arch. The Arch and the double-arched London Bridge were formed in this way and are still being eroded by the sea.

As erosion by the sea continues, these arches will eventually collapse to produce stacks--residual areas of harder rock isolated from the original land surface. One group of such stacks is the Bay of Islands, and another, the most striking, is The Twelve Apostles. These stacks are of various sizes; many rise to more than 100 metres above sea level, while others have almost been eroded away entirely. The development of beaches is slowing down the erosion of the cliffs in some places.

This coast had a reputation as the graveyard of many sailing ships in the 19th century. Even a slight swell will produce the treacherous surf that has battered ships against the cliffs and caused the deaths of many sailors.

The Loch Ard Gorge was named after the most notable of these shipwrecks. The Loch Ard, a three-masted iron clipper, was wrecked in 1878, with the loss of 50 lives. Many of the victims were buried in the plain close to the gorge, in what is still known as the Loch Ard Cemetery.

The small islands, rock stacks and cliff ledges provide nesting sites for many sea birds, especially short-tailed shear-waters, or muttonbirds (Puffinus tenuirostris). One rock stack has been named Muttonbird Island; the birds may be seen most clearly when they fly in at dusk. They nest in colonies of up to 200,000 birds within a very small area.

Each year, in late April, after the breeding season, the adult muttonbirds fly north to Japan and Alaska. They return in late September to prepare their nest burrows, by excavating a soft sandy spot, and mate. The hen usually lays one egg. The young birds are left unattended during the day and are fed by the parents each night when they return from the sea.

Among other species of birds in the Port Campbell National Park are pied and sooty oystercatchers, which live on molluscs and other small sea creatures they hunt along the shore. The pied oystercatcher (Haematopus ostralegus) nests in depressions made in the sand, whereas the larger and less common sooty oystercatcher (Haematopus fulignosus) generally nests on the offshore islands and rock stacks, well above sea level.

Along the beaches, pairs of hooded dotterels (Charadrius rubicollis) may be seen picking out food as each waves recedes. These birds also nest on the ground, usually in a depression in the sand, in a shell bank or in seaweed. The smaller sea birds often become the prey of the peregrine falcon (Falco peregrinus), which nests on the cliff ledges.

Other species of birds are confined to the narrow coastal strip of windswept heath. These include the tiny southern emu-wren (Stipiturus malachurus), the brown quail (Coturnix australia), the pretty blue-winged parrot (Neophema chrysostoma) and the tawny-crowned honeyeater (Phylidonyris melanops).

The coastal plain area is characterized by generally sparse heath vegetation of low shrubs and grasses because the soil is poor and holds little moisture. Here and there the heath is interspersed with clumps of drooping she-oaks (Casuarina stricta). which are adapted to the dry and windy environment by having needle-like leaves that lose little water through transpiration. Stunted examples of messmate stringybark (Eucalyptus obliqua) are also found. In regions away from the coastal plain, where there are better soil and higher rainfall, this is one of the tallest of the eucalypts.