GEOGRAPHIC EXTREMES SOCIETY
AUSTRALIAN RECORDS
Sand Dunes
Many publications claim that Dune 7 in Africa’s Namib Desert to be the world’s largest sand dune. It is exceptional large at 383 metres and it made entirely from sand. Other claims of enormous sand dunes usually have the dunes on existing mountains with just a veneer of sand covering an underlying rocky substrate.
Dune 7. Largest sand dune in the world. Image supplied by Kurt Cotoaga
Australia ranks much higher on the world-scale with the size of its dune fields. Australia’s dune fields rate as some of the most extensive on the planet.
Sand doesn’t always consist of siliceous grains of weathered rock. When sand accumulates on beaches, biological material in the form of shells, corals, and marine exoskeletons mix with the siliceous sands that grace large sections of the coastline. In northern Australia, the prevalence of biological material, especially calcium carbonates, is much higher due to the extensive coral reefs. In Western Australia’s coast south of Carnarvon, the last 10,000 years has seen the predominance of broken down and weathered turban shells contributing to the beach sands. These shells have been the major contributor to the Tamala limestone formations along the western coast. In Shark Bay, the high salinity of the Hamelin Pool area has resulted in some beaches being entirely composed of Hamelin cockle shells, whose deposits are up to ten metres deep. The best place to witness these agglomerations of billions upon billions of cockle shells is at Hamelin Pool itself or further north near the township of Dampier where the saline pools of the Burrup Peninsula have again created ideal conditions for the cockle shells to domineer.
Hamelin Cockle Shell dominate in hypersaline waters. Source: Stephen Scourfield
Most of us have been to the beach or stood on a desert sand dune and experienced the grains of sand being swept along by strong winds. As the wind ruffles over the surface of the sand, the strength and direction of the breeze can determine the shape and height of the ensuing sand dunes, and these can be quite variable. Of the many weird and wonderful examples of dune shapes, there are two types most commonly found in Australia whose records we will examine for extremes – parabolic and linear sand dunes.
Largest Mobile Dunes
Parabolic dunes in Australia are predominately associated with coastal sand blows, similar to the Cooloola Sand Blow north of Noosa in Queensland, Stockton Beach north of Newcastle in New South Wales, and the Henty Dunes near Strahan in Tasmania. Although Stockton Beaches and Henty dune system are impressive, the claims to the largest in the Southern Hemisphere are erroneous. The rarely visited, Bilbunya Dunes off Balbinya Beach in southern Western Australia, are enormous encompassing an area two times Stockton Beach and three times greater than their Henty Beach counterparts. Balbinya Beach is part of the recently uplifted coastline adjacent to the Wylie Scarp, part of the Great Southern Scarp.
Bilbunya Dunes – Largest mobile coastal sand dunes in Australia. Image: letmebefreeblog
Largest Star Dune
The Bilbunya Dunes is also home to Australia’s on Star Dune sytems. Sixteen enormous Star Dunes characterise this area, the largest at 125 metres. Star Dune are formed when the direction of the wind is changeable and the dune can grow from three or more directions.
Bilbunya Dunes. Largest Star Dune in Australia. Image: Andrew Short UNSW
Longest Coastal Sand Dune
Along the same coast of Western Australia there is another amazing coastal sand blow that is today largely unknown. We are talking about the stabilised sand blow which runs for 110 kilometres from Twilight Cove to just south of Madura on the Eyre Highway. This is the longest sand dune originating from the coast. Twilight cove is at the very end of the Baxter Cliffs which run for 160 Kilometres before turning inland to form the beautiful Hampton Range. At the very start of the sand blow, sand has managed to ramp up over the cliffs and disperse inland, but the majority of the sand was pushed during the previous ice-age along the coastal Roe Plains.
In the image below, the darker patch in the centre of the Roe Plains represents the historic sand blow.
Twilight Cove Sand Blow. Largest sand blow in Australia. Image: Google Maps
Longest Parabolic Dunes
Parabolic dunes have long, trailing arms and they reach their greatest extent at Shark Bay and on Cape York Peninsula. Two separate locations on Cape York Peninsula – Cape Grenville and Cape Flattery – are sandy basins where parabolic sand dunes have only recently become mobile again. The largest uninterrupted parabolic sand dunes in Australia are at Shark Bay, Western Australia and on Cape York Peninsula’s, Cape Grenville and Cape Flattery. The Carrarang sand blow at Shark Bay began as a simple parabolic dune which started its life at a break in the Zuytdorp Cliffs at False Entrance Bay. A constant southerly wind pushed wave transported sands through a break in the cliffs before wind-blown sand fed the large dune system, that extends for twenty-two kilometres northwards.
Carrarang Sand blow – Longest unbroken parabolic dune. Image: Google maps
The parabolic dunes have broken down these days onto a succession of transgressive dunes with multiple peaks and troughs. This dune system does, however, hold the record for the longest unbroken coastal sand dune at fourteen kilometres before a break in the sand blow allows a road for travellers to access Steep Point. Carbonate grains compose over 60% of the sand at Carrarang. Right along this coast there is evidence of massive sand build up during previous periods of lower sea levels. In some cases sand ramps allowed wind-blown sand to scale massive cliff faces before rising sea levels eroded the sand ramps away. In places like Dirk Hartog Island the sand has become a stranded veneer gradually blowing off the and exposing sections of underlying sedimentary rocks.
On Cape York Peninsula, the persistent south-easterly trade winds of the dry season, have blown the sand into extensive parabolic dunes which extend for an incredible twenty-eight kilometres at Cape Flattery. At the same time, Cape Grenville takes the Australian record with a dune length of twenty-nine kilometres, with the longest unbroken section of eight kilometres.
Around Cape Grenville and the adjacent Shelburne Bay, the parabolic dunes run in lines pushed by the constant roar of south-easterly trade winds.
Cape Grenville sand dunes – Longest parabolic dunes in Australia. Image: Google Maps
Four hundred kilometres to the south of Cape Grenville, the parabolic dune fields of Cape Flattery are just as extensive, although the longest unbroken dune is twelve kilometres in length. Cape Flattery is home to the world’s largest silica mine, operated by the Mitsubishi Corporation. The sands around Cape Flattery hold some of the planet’s most pure silica sands.
Cape Flattery Sand Dunes. Purest silica dunes Image: Google Maps
Largest Linear Dune system
Linear or sometimes referred to as parallel sand dunes are characteristic of the Australian deserts, and arid interior. The Australian arid zone contains the world’s largest linear dune systems on the planet. The structure and alignment of the linear dunes in central Australia resemble a giant fingerprint when drawn on the Australian map. This fingerprint alludes to the continued presence of subtropical high-pressure systems which dominated central Australia’s weather pattern during past ice ages.
Alignment of Australia’s linear dune systems. Image: Mary E White
Successive ice ages led to the creation of the complex linear dune fields. The greatest period of sand dune development occurred in the most recent ice age and the telltale positioning of the dunes records where the subtropical high-pressure systems hovered during this time.
Simpson Desert Linear dunes – Longest linear dunes in the world. Image: Google Maps
Largest mobile linear dune
Interglacial periods, like we are in are experiencing at present, has the majority of dune systems ceasing their slow wanderings and rainfall allows the colonisation of sparse vegetation and the development of associated soil fungi and biota, which have anchored the desert sand dunes in place. The largest mobile linear (parallel) sand dune in Australian deserts is the famed ‘Big Red’ (or Nappanerica) dune at 40 metres high on the eastern edge of the Simpson Desert near Birdsville.
Sand Records
GES Record: Largest sand dune in the world – Dune 7. Namib Desert. Namibia. 383 metres (Source: scribol.com/environment/desert/10-tallest-sand-dunes-on-earth )
GES Record: Largest sand dune in Australia – Mount Tempest. Moreton Island. Queensland. (Source: Aussie Bushwalking website)
GES Record: Largest mobile beach dune system – Bilbunya Dunes. Western Australia. 5,200 ha (Source: Andrew Short. UNSW)
GES Record: Tallest Star Dune in Australia – Bilbunya Dunes. Western Australia. 125 metres (Source: Andrew Short. UNSW)
GES Record: Longest coastal sand blow in Australia – Twilight Cove Sand Blow. Western Australia. 110 kilometres (Source: Andrew Short. UNSW)
GES Record: Tallest mobile desert sand dune. – Big Red. Simpson Desert. Queensland. 40 metres (Source: Rachel Dixon. Deserts and Savannah’s in Australia. 2018)
GES Record: Oldest sand dunes in Australia – around Lake Amadeus. Northern Territory. Approx. 980,000 years old (Source: Chen and Barton 1989)
GES Record: Longest parallel dunes – Simpson Desert. Northern Territory and into South Australia. 200 kilometres? (Source: CR Twidale 1980)
GES Record: Longest unbroken parabolic dune system – Carrarang. Shark Bay. Western Australia. 22 Kilometres (Source: RJ ANDREWS 2020 )
GES Record: Longest parabolic dunes. Cape Grenville. Queensland. 29 kilometres. (Source: Short, Woodroffe, The coasts of Australia. 2009 )
The Geographic Extremes Society welcomes any input as to the veracity of these records and we encourage everyone to contribute to these extreme records by contacting us to initiate the discussion