Simpson Desert

Ted Colson's expedition across the Simpson Desert in 1936

The Simpson Desert from space by NASA's Moderate-Resolution Imaging Spectroradiometer (MODIS), showing dust storm on 16 December 2007

Big Red, Simpson Desert, 2007

The Simpson Desert is a large area of dry, red sandy plain and dunes in Northern Territory, South Australia and Queensland in central Australia. It is the fourth largest Australian desert, with an area of 176,500 km² (68,100 sq mi).

The desert is underlain by the Great Artesian Basin, one of the largest inland drainage areas in the world. Water from the basin rises to the surface at numerous natural springs, including Dalhousie Springs, and at bores drilled along stock routes, or during petroleum exploration. As a result of exploitation by such bores, the flow of water to springs has been steadily decreasing in recent years.

The Simpson Desert is an erg which contains the world's longest parallel sand dunes. These north-south oriented dunes are static, held in position by vegetation. They vary in height from 3 metres in the west to around 30 metres on the eastern side. The largest and most famous dune, Nappanerica, or more popularly Big Red (named by Simpson Desert traveller Dennis Bartell), is 40 metres in height.

History

The explorer Charles Sturt, who visited the region from 1844–1846, was the first European to see the desert, but it was not until 1936 that Ted Colson became the first white person to cross it in its entirety. The name Simpson Desert was coined by Cecil Madigan, after Alfred Allen Simpson, an Australian philanthropist, geographer, and president of the South Australian branch of the Royal Geographical Society of Australasia. In 2008, Belgian explorer Louis-Philippe Loncke became the first person to cross on foot and completely unsupported the length of the Simpson desert, which was North to South and passing through its geographical center. In 1967, the Queensland Government established the Simpson Desert National Park.

No maintained roads cross the desert. However, there are tracks that were created during seismic surveys in the search for gas and oil during the 1960s and 1970s. These include the French Line, the Rig Road, and the QAA Line. Such tracks are still navigable by well-equipped four-wheel-drive vehicles which must carry extra fuel and water. Towns providing access to the South Australian edge of the Simpson Desert include Innaminka to the south and Oodnadatta to the southwest; and from the eastern (Queensland) side include Birdsville, Bedourie, Thargomindah and Windorah. Last fuel on the western side is at the Mount Dare hotel and store. Before 1980, a section of the Commonwealth Railways Central Australian line passed along the western side of the Simpson Desert.

The desert is popular with tourists, particularly in winter, and popular landmarks include the ruins and mound springs at Dalhousie Springs, Purnie Bore wetlands, Approdinna Attora Knoll and Poeppel Corner (where Queensland, South Australia and Northern Territory meet). Because of the excessive heat and inadequately experienced drivers attempting to access the desert in the past, the Department of Environment and Natural Resources has decided since 2008-2009 to close the Simpson Desert during the summer — to save unprepared "adventurers" from themselves.

Some of the heaviest rain in decades occurred during 2009-2010, and has seen the Simpson Desert burst into life and colour. Rain inundated Queensland’s north-west and Gulf regions. In total, 17 million megalitres of water entered the State’s western river systems leading to Lake Eyre. In 2010, researchers uncovered the courses of ancient river systems under the desert.

Ecology

The IBRA regions, with the Channel Country in red

The IBRA regions, with the Simpson-Strzelecki Dunefields in red

The Simpson Desert is also a large part of the World Wildlife Fund ecoregion of the same name which consists of the Channel Country and the Simpson Strzelecki Dunefields bioregions of the Interim Biogeographic Regionalisation for Australia (IBRA).

The flora of the Simpson Desert ecoregion is limited to drought-resistant shrubs and grasses especially Zygochloa paradoxa grass that holds the dunes together and the spinifex and other tough grasses of sides slopes and sandy desert floor between the dunes. The Channel Country section of the ecoregion lies to the northeast of the desert proper around the towns of Bedourie and Windorah in Queensland, and consists of low hills covered with Mitchell grass cut through with rivers lined with Coolabah trees. The ecoregion also includes areas of rocky upland and seasonally wet clay and salt pans, particularly Lake Eyre, the centre of one of the largest inland drainage systems in the world, including the Georgina and Diamantina Rivers.

Wildlife adapted to this hot, dry environment and seasonal flooding includes the Water-holding Frog (Litoria platycephala) and a number of other reptiles that inhabit the desert grasses. Endemic mammals of the desert include the kowari (Dasycercus byrnei) while birds include the Grey Grasswren (Amytornis barbatus) and Eyrean Grasswren (Amytornis goyderi). Lake Eyre and the other seasonal wetlands are important habitats for fish and birds, especially as a breeding ground for waterbirds while the rivers are home to birds, bats and frogs. The seasonal wetlands of the ecoregion include Lake Eyre and the Coongie Lakes as well as the swamps that emerge when Cooper Creek, Strzelecki Creek and the Diamantina River are in flood. The birds that use these wetlands include the Freckled Duck (Stictonetta naevosa), Musk Duck (Biziura lobata), Silver Gull (Larus novaehollandiae), Australian Pelican (Pelecanus conspicillatus), Great Egret (Ardea alba), Glossy Ibis (Plegadis falcinellus), and Banded Stilt (Cladorhynchus leucocephalus). Finally the mound springs of the Great Artesian Basin are important habitat for a number of plants, fish, snails and other invertebrates.

Native vegetation is largely intact as the desert is uninhabitable so habitats are not threatened by agriculture but are damaged by introduced species, particularly rabbits and feral camels. The only human activitiy in the desert proper has been the construction of the gas pipelines, while the country on its fringes has been used for cattle grazing and contains towns such as Innamincka. Mound springs and other waterholes are vulnerable to overuse and damage. Protected areas of the ecoregion include the Simpson Desert, Goneaway, Lochern, Bladensburg, Witjira and Lake Eyre National Parks as well as the Simpson Desert Conservation Park, Innamincka Regional Reserve and Simpson Desert Regional Reserve.

The Dunes

Morphology

4WD touring in the Simpson Desert requires careful preparation.

The sand ridges have a trend of SSE-NNW and continue parallel for kilometers. This pattern is seen throughout the Deserts of Australia. Some of the ridges continue unbroken for up to 200 km. The height and the spacing between the ridges are directly related. Where there are 5-6 ridges in a kilometer, the height is around 15 meters but when there is one or two ridges per kilometer the height jumps to 35-38 meters. (Twidale, 1980) In cross section, the Lee side is the eastern slope with an incline of 34-38 degrees, while the Stoss side is the western slope with a incline of only 10-20 degrees. In cross section, the cross beds are planar with foresets alternating between east and west. The foresets have incline angles of 10-30 degrees. (Twidale, 1980)

Sediment

The sand is predominately made up of quartz grains. The grains are rounded and sub angular. They range size from 0.05mm to 1.2mm with 0.5mm being the average size for the crests and 0.3 being the average size on the dune flanks. The active crests have well sorted sand sediment but on the interdunes, the sediment is not as well sorted. (Twidale, 1980) The sediment varies in color from pink to brick red but by the rivers and playas the sediment color is light grey. The progression of the color from grey to red is due to the release of iron oxide from the sediment when weathered. (Twidale, 1980)

See also

• Australasia ecozone
• Ecoregions of Australia
• List of deserts by area
• Simpson Desert Conservation Park
• Simpson Desert Important Bird Area
• Simpson Desert Regional Reserve

External links

Media related to Simpson Desert at Wikimedia Commons

• Aerial Video footage of the Simpson Desert
• Reading the Simpson Desert
• The Bibliography of Aeolian Research
• Into the Simpson Desert: audio blog at the National Museum of Australia