Fraser's vast sandblows demonstrate in perpetuity the World Heritage value of ongoing geological change. Photo: Tourism Queensland.
Continuously covered and uncovered by moving sands, these fragile expanses of coffee rock seem to ebb and flow like the tide itself. Photo: Queensland Government
Wanggoolba Creek is sacred to the Butchulla people and provides a tranquil place to wander in the cool rainforest at Central Station. Photo: Tourism Queensland.
Scattered throughout the island where the water table is high, swampy heaths provide perfect habitat for acid frogs and other specialised species of fauna and flora. Photo: Tourism Queensland.
Mangroves along the west coast of Fraser Island are important in the marine food web of Great Sandy Marine Park. Photo: Queensland Government
Building the sandmass—wind, waves and changing sea levels
Over the past two million years, ocean currents and waves have swept sand north from the continental shelf of New South Wales and southern Queensland. Sand accumulates and covers the bedrock to form dunes parallel to the coast, leaving only peaks uncovered—today's headlands.
Strong onshore winds blow some loose sand inland into high parabolic (hairpin-shaped) dunes, which spread to engulf everything in their paths and form a sequence of overlapping dunes.
Fraser Island and Cooloola are remnants of old sandmasses that once stretched 30km east. Major dune-building has continued in episodes as sea levels rose and fell, forming a sequence of at least 8 overlapping dune systems of different ages. Some are more than 700,000 years old—the world's oldest recorded sequence. These processes continue shaping the sandmasses.
Sandblows form when strong onshore winds break through the vegetation cover, driving sand from the eroding dunes. Sandblows engulf forests in their path, at a rates of up to 1 metre each year. New sandblows can also form when the stabilising plant cover is damaged by fire and wind, walkers or vehicles.
Scattered along the beaches are outcrops of soft, dark-brown 'coffee rock', made up of sand grains weakly cemented together by organic matter (plant remains). Coffee rock is a remnant of a time when the sandmass stretched further to sea—and the currently exposed coffee rock was further inland and a part of the sandmass soil layers.
Underlying parts of the windblown sandmasses of Fraser Island and Cooloola are coloured sands—the visible parts of older sand that has bound with clay into a weakly consolidated mass. These yellow, brown and red colours were created as iron-rich minerals stained the sand a complex array of tones and hues over thousands of years. Spectacular sculptures emerge where wind and rain erode the sandmass, exposing this soft older core. The Pinnacles and Red Canyon are striking examples.
Lakes in porous sands
Amazingly, each of the freshwater dune lakes in the Great Sandy National Park is unique in shape and colour. More than 40 dune lakes occur here—over half of the known world total. Lake Boomanjin, the world's largest perched lake at 200ha and Boomerang Lakes, some of the world's highest at 120m above sea level are on Fraser Island.
Perched lakes such as Birrabeen and Lake McKenzie on Fraser Island and Lake Poona in Cooloola are the most common type of lake in Great Sandy National Park. These lakes develop when a saucer-shaped 'hard pan' of organic debris, sand and peat forms in a depression between dunes enabling run-off and rainwater to collect and slowly filter to the watertable below.
Barrage lakes form when a mobile sand dune dams a watercourse, usually in younger dunes close to the coast. Interested visitors can walk to Lake Wabby on Fraser Island, from the eastern beach.
Window lakes, generally found at low elevations, form where the ground surface drops below the watertable level and fills with groundwater. Some window lakes are barraged by sand dunes.
All the freshwater lakes are low in nutrients and support few plants and animals. Most lakes have only two or three fish species.
Eli and Wanggoolba Creeks are noted for their flow of crystal clear water—mainly localised outflows of groundwater from the sandmass. They contrast with the golden-brown, tannin stained creeks and seepages that flow into Lake Booomanjin.
How are forests created on bare sand?
Most plants growing on sand draw mineral nourishment from two unlikely sources. They strip the fine mineral coating from grains of beach sand turning the yellowish grains white and also absorb small amounts of atmospheric trace minerals, washed into the sand by rain.
Decaying plants return these minerals to the sand. Over time, minerals are concentrated in the sandmass, providing nutrients to support a succession of forest types, from coastal pioneers and shrubby woodlands to tall rainforests.
As each successive dune forms, a thicker, deeper nutrient layer develops, able to support taller, more complex forest.
But on Great Sandy's older dunes the nutrient layer has been leached by water beyond the reach of even deep tree roots. The tall forests are replaced by stunted woodlands, shrubs and low heaths. This phenomenon—'retrogressive succession'—is of international scientific interest.
Older dunes generally lie to the west on Fraser Island, overlaid partly by progressively younger dunes to the east.
Beaches—home in shifting sand
Life is abundant—pipis (shellfish) and moon snails live in the shifting intertidal sand; sand-bubbler crab colonies leave patterns of tiny sand balls; ghost crabs scuttle across the sand at night.
Watch out for bluebottles with long blue stingers, sometimes washed ashore following strong winds. Flotsam, such as jellyfish is food for scavenging crabs and birds, adding nutrients to the sand.
Pioneers and coastal forest—holding dunes together
Holding the coastal foredunes together are salt-tolerant pioneer plants: pigface, with fleshy angular leaves and purple flowers, goatsfoot vine, with purple trumpet flowers, and beach spinifex, that creeps over the dunes and traps sand swept from the beach by the wind.
Pioneer plant species begin nutrient and soil development. Their roots host bacteria that convert airborne nitrogen into nitrates that enrich the soil. Small, hardy trees such as beach casuarina, coastal banksia and pandanus are a more permanent stabilising force on the foredunes. They protect the wattles, hopbush, tuckeroo and stunted eucalyptus trees from harsh salt-laden winds.
Abundant banksia flowers provide plentiful food for the insects and nectar-feeding birds in these coastal forests.
Protected from the harshest salt-laden winds, and growing where richer sand begins to develop, trees in the mixed forests and woodlands are larger than those of the coastal forests, although more stunted than the same species in the tall eucalypt forests.
Fires clear the understorey of foxtail sedge, bracken, blady grass, and fallen leaves and twigs, and provide an ashbed for new seedling growth. Over time, trees develop hollows that shelter nesting birds and nocturnal gliding possums. Ant nests are conspicuous on the forest floor, and more than 300 species of ants have been recorded in Great Sandy.
Protecting the forest core here are tall eucalypt trees, including smooth-barked forest red gums and scribbly gums. These tall trees contrast with tessellated barked bloodwoods, string-barked satinays, and blackbutts, with their rough-barked bases and smooth, light upper limbs.
Tall eucalypt forest grows on the ridges on the high middle dunes in the centre of the sandmass. It surrounds the central forest core, protecting the rainforest from the drying winds and salt.
After fire, eucalypts of the tall forest regenerate from seeds released into the ash bed. The burnt trees also sprout new leaves from special buds protected under thick bark, and from lignotubers—woody tissue attached to the root system—below the ground.
Blackbutt trees were the mainstay of the timber industry on Fraser Island. Visitors can see remnant stumps of former giants and large, shield-shaped scars near the base of some trees, where Indigenous people removed the bark for their gunyahs (shelters).
The slopes and valleys of the middle, high dunes have the best protection from winds, receive the highest rainfall and have the deepest accessible soils. They are dominated by huge brush box, with bark 'stockings' on their lower trunks and smooth red limbs, and the tall, straight-trunked, stringy-barked satinay, whose long roots reach rich nutrients buried deep in the dunes.
In other areas, lichen-covered trunks of giant kauri and hoop pine emerge above lilly-pilly, quandong, brush box, and strangler figs, draped in vines, orchids, ferns and mosses. Walk slowly to see colourful fungi sprouting on rotting trees, their fine threads slowly decomposing the wood.
These rainforests are known as vine forests. Along their drier margins, the low vine forests of small-leafed grey myrtle ('carrol' scrubs) can be seen on walks from Central Station.
Hollows in older trees offer nesting sites for mammals and for birds including king parrots, yellow-tailed black cockatoos and sulphur-crested cockatoos, often heard screeching from treetops. Brushtail possums are active at night, as are sugar gliders and flying-foxes.
Wallum communities dominate the older western dune systems, where the main nutrient layer has leached down beyond the reach of tree roots. Only shrubs and smaller trees can grow on this relatively infertile upper sand layer. In seasonally waterlogged areas, paperbark and wet heathlands grow in dense stands.
Scribbly gum, pink bloodwood, wallum banksia (with serrated leaves) and black casuarinas (with needle-like leaf stems) grow as low trees above the heathy understorey.
Look closely at the hard wallum banksia seed cases, which will only open after the heat and smoke of fire, releasing seeds that take advantage of the lack of competition after a fire. Most of Great Sandy's plant communities respond to the frequency, season and intensity of fires.
Heaths and swamps
Swampy, treeless, grassy plains, fringed by paperbarks, colourful heath and swamp banksias, feed tea-coloured water to creeks and lakes. These are wallum heathlands.
Frequent fire maintains grassy heathlands by inhibiting tree growth. This preserves habitat and food for fairy wrens and ground-dwelling birds such as quails and ground parrots. Heaths and swamps are home to 'acid' frogs, which are able to tolerate the mildly acidic waters, the harmless freshwater snake, and several crustaceans.
Mangroves—forests on intertidal mudflats
Swarms of biting insects and the occasional waft of decomposition mean mangroves are not always pleasant places to visit. But the shelter of their roots and the deep layers of decomposing leaf litter make mangroves ideal nurseries and feeding grounds for much marine life in Great Sandy. Mangroves are also important in the food webs of nearby heathlands. Great Sandy's mudflats and sandflats are major feeding grounds for migratory shorebirds such as bar-tailed godwits on their flights from the northern to southern hemispheres.
Bleached and fragile, the windswept shells of marine bivalves form the heart of middens; important reminders of the enduring relationship Butchulla people have with K'gari (Fraser Island). Photo: Queensland Government
The timber industry and those associated with it have helped shape the island to what it is today. Photo: Queensland Government
People of Great Sandy: First inhabitants
Archaeological evidence suggests Aboriginal people have lived in the Great Sandy area for at least 5000 years, but they may have been here far longer. Butchulla people inhabited Fraser Island and the adjacent mainland living a complex, self-sufficient way of life intimately connected with the seasons, the land, and life on it. The abundance of marine life along the coast provided the Butchulla with many foods, including fish and shellfish. Food also came from the forests, along with bark for canoes and shelters, vines for nets, and grasses and piccabeen palm fronds for baskets.
Today, K'gari (Fraser Island) contains heritage sites of spiritual, social and archaeological significance. Middens, artefact scatters, scarred trees and campsites bear witness to the lifestyle of the Butchulla people.
Aboriginal life was disrupted soon after European settlement in the 1840s. Dispossession of land and reduced access to native plants and animals caused disruption to beliefs and practices, and disease, alcohol and opium destroyed the traditional way of life. Clearing of land for pasture and the advent of timber harvesting in the 1860s hastened the demise of local lifestyles. By the late 1800s, most remaining Aborigines from the region were relocated to a mission settlement on Fraser Island. A succession of missions followed until the final Fraser Island mission was disbanded in 1904, when most Aboriginal inhabitants were sent to various Queensland missions, including Yarrabah near Cairns. Many local place names are Aboriginal. Today, descendants live in the area and are striving to share their knowledge of a once widespread way of life.
Changing European uses
The first written record of the region is from Cook's discovery voyage of Australia's east coast in 1770. However, references to the area in old Portuguese navigation charts, and lead weights mined in France between 1410 and 1627AD, found on one of Fraser's beaches, suggest Europeans may have visited the region well before Cook.
Early impressions of the region were not positive. Matthew Flinders, the first English explorer to set foot on Fraser Island in 1802, noted: 'Nothing can be imagined more barren than this peninsula'. That perception changed in 1842, when pioneer Andrew Petrie reported good pastoral lands and excellent forests in the area. This attracted settlers, who grazed horses, sheep and cattle at Cooloola and Fraser Island.
Logging of valuable kauri pines began on Fraser Island in 1863 and Cooloola in 1866. After the Gympie gold rush of 1867 demand for timber boomed and logging expanded to become the region's major industry for more than a century.
Small-scale mining for heavy minerals, mainly rutile and zircon, began with mining leases granted on Fraser Island in 1949. Sandmining exploration increased in the 1960s, attracting opposition from conservation-minded individuals and community groups. Their efforts eventually ended sandmining in Great Sandy in 1976, while logging stopped in late 1991. National parks were declared in the northern part of Fraser Island in 1971 with more additions in later years. 1992 saw the significant listing of Fraser Island as a World Heritage Area.
Residents have used the area for recreation since the 1870s. Tourism grew slowly. The first commercial tours and accommodation on Fraser Island not starting until the 1930s. This changed with the controversies surrounding sandmining in the 1970s and cessation of logging in the early 1990s, which dramatically increased visitor interest. The 1992 World Heritage listing of Fraser Island increased international visitation.
The challenge for today's management is to balance the conservation of the region's natural and cultural assets with increasing opportunities for people to enjoy the magnificent values of Fraser Island, World Heritage Area.