Situated just 17 kilometres south of Cervantes in the Nambung National Park, the Pinnacles Desert is a major tourist attraction in the region. Attracting approximately 250,000 visitors every year, the Pinnacles Desert covers an area of approximately 190 hectares, and contains thousands of limestone pinnacles, some up to five meters high. The variation in colours (due mainly to the variation in soil types), and the stark relief of the Pinnacles – amid a backdrop of constantly shifting sand dunes – creates an eerie landscape of ever-changing moods. It is best viewed at dawn or sunset when the shadows create remarkable patterns and shapes that ripple over the sands.
So how did these strange pinnacles form?
The coast of Western Australia, from Shark Bay to Albany, has a near continuous belt of Tamala Limestone (aeolian calcarenite, i.e., wind-blown calcium carbonate) – which has been produced by the combination of wind, rain, and the cementing agent of calcium.
A set of unique circumstances produced the Pinnacles. Firstly the huge sand dunes stabilised, and then rains fell on the dunes which, over a very long period, leached down through the sand carrying the calcium. This resulted in the lower levels of the dune solidifying into soft limestone. As this stabilisation occurred, a layer of soil formed on top of the dunes which allowed plants to grow and further cemented the limestone below. Gradually the lowest layer of soil, which lay between the surface and the limestone, formed into a hard cap which resulted in the old dunes having three levels – a soil and plant level near the surface, a hard cap below the surface, and a thick layer of soft limestone at the bottom of the dune.
Inevitably the roots from the plants on the top level found cracks and broke up the hard cap and the layer of soft limestone. The result was that under a surface covered with plants and soil the Pinnacles developed. No one knows for sure how long ago this process occurred. It may have started as long as 500,000 years ago, but equally it may only be a few thousand years old, and it may still be continuing today. The Western Australian Museum has estimated that it has occurred sometime in the last 80,000 years.
Drier climatic conditions in the region have since resulted in the top layer of plants and soil being eroded, gradually exposing the Pinnacles so that today, they stand like strange sentinels on a plain of wind-blown sand.
The Pinnacles are accessible via a fully sealed road, and sightseers are advised to allow for at least two hours to follow the viewing trail and access the lookout. Entry fees to the park are $13.00 per passenger vehicle (pensioner discounts apply) and are payable at the gate. Caravans and trailers can be left in the car park, as the four kilometre loop is not suitable for these. Pets, open fires, and camping are all prohibited within the park boundaries. Hats, sunscreen and water are essential pre-requisites for a visit to the Pinnacles, especially during the summer months.
Source: Pinnacles Visitor Centre www.visitpinnaclescountry.com.au