Australasia

Sands of time

Sand

The world’s largest sand island is more than just a giant beach

 

There are no castles on Fraser Island but if there were, they would be built on sand. On the Queensland coast some 184,000 hectares of quartz grains make a platform for lakes, wildlife and a surprisingly flourishing rainforest. Dunes stretch up to 244 metres above sea level on an island that is 122 kilometres (75 miles) long and up to 22 kilometres (13 miles) wide. Some 250 kilometres (155 miles) of beaches surround the inland.

The island has formed over some 700,000 years. Yet sand started to accumulate long before. Some 700 million years ago, when Antarctica was attached to Australia, eroded mountain ranges turned to sand. Along with grains from south-east Australia, it travelled towards the Queensland coast through winds, waves and ocean currents. It settled on the continental shelf before drifting towards the mainland in a zigzag pattern.

The process was helped by changing temperatures regulating ocean levels. During low tide, more sand became visible and started travelling across the surface. The volumes were so large that plants could not stabilise it. Over time, it settled. This created a number of islands, though there is a reason why Fraser became the largest. It used to be a low, hilly terrain formed by volcanic activity millions of years ago, and became an easy catchment area for travelling grains.

Sand

The dune system is still evolving. The volume of travelling sand depends on wind and moisture. Most dunes rise to between 100- and 200 metres above sea level. About 98 per cent is quartz. In one area, oxide-coated sand grains have created 72 different sand colours. Most are variations of red and yellow.

Along the island’s eastern shore lies the Seventy-Five Mile Beach. Tracks in the sand of four-wheel drives reveal its usage. On this stretch, regular highway rules apply, including a speed limit of 80 kilometres (49 miles) per hour. Unlike a highway, however, vehicles must occasionally give way for planes landing on the strip. Wildlife includes sea birds and dingoes. The waters are good for fishing but not swimming, as large sharks roam.Sand2

Inland, a rich rainforest thrives. Remarkably, it lives off nothing but water and sand, which is notoriously low on nutrient essentials to plant growth. The forest is sustained by natural mechanisms. Along the shore, the air contains nutrients from sea spray. These are deposited in the sand. As sand travels inland, fungi make the nutrients available to the plants, which in exchange provide various organic compounds. This ecosystem trade-off permanently sustains a forest that stretches up to 50 metres tall.

Not all of the island’s features are constructive. Between 1856 and 1935, more than 20 shipwrecks crashed into the coastline. In 1870, locals tried to arrest the trend by building a lighthouse. It had little effect. One shipwreck in particular, the Maheno, has become a landmark attraction. One of the first turbine-driven steamers, it sailed regularly between Sydney and Auckland before becoming a hospital ship during World War One. In 1935 it was sold to Japan for scrap. En route, a cyclonic storm snapped the tow chain. The Maheno drifted helplessly onto the Fraser Island shore.

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Photos: col, janelle Lugge, Marcos81 [all via Shutterstock.com].

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