Nullarbor Plain


The Nullarbor Plain is part of the area of flat, almost treeless, arid or semi-arid country of southern Australia, located on the Great Australian Bight coast with the Great Victoria Desert to its north. It is the world's largest single exposure of limestone bedrock, and occupies an area of about. At its widest point, it stretches about from east to west across the border between South Australia and Western Australia.

History

Historically, the Nullarbor was seasonally occupied by Indigenous Australian people, the Mirning clans and Yinyila people. Traditionally, the area was called Oondiri, which is said to mean 'the waterless'.
The first Europeans known to have sighted and mapped the Nullarbor coast were Captain François Thijssen and Councillor of the Indies, Pieter Nuyts, on the Dutch East Indiaman 't Gulden Zeepaert. In 1626–1627, they charted a stretch of the southern Australian coast east of Cape Leeuwin and extending to longitude 133 30'E. While the interior remained little known to Europeans over the next two centuries, the stretch of coast adjoining the Great Australian Bight was named for Nuyts, and maps subsequent to 1627 bore the legend "Landt van P. Nuyts" or "Terre de Nuyts". That survives as two geographical names in West Australia: Nuytsland Nature Reserve and Nuyts Land District, and in South Australia as Nuyts Reef, Cape Nuyts and the Nuyts Archipelago.
Edward John Eyre became the first European to successfully cross the Nullarbor in 1841. In writing about Eyre's voyages in 1865, Henry Kingsley wrote that the area across the Nullarbor and Great Australian Bight was a "hideous anomaly, a blot on the face of Nature, the sort of place one gets into in bad dreams". Eyre departed westwards from Fowlers Bay on 17 November 1840 with John Baxter and a party of three Aboriginal men. When three of his horses died of dehydration, he returned to Fowler's Bay. He departed with a second expedition on 25 February 1841. By 29 April, the party had reached Caiguna. Lack of supplies and water led to a mutiny. Two of the Aboriginal men killed Baxter and took the party's supplies. Eyre and the third Aboriginal man, Wylie, continued on their journey, surviving through bushcraft and some fortuitous circumstances such as receiving some supplies from a French whaling vessel anchored at Rossiter Bay, some east of Esperance. They completed their journey in Albany in June 1841.
In August 1865, while travelling across the Nullarbor Plain, Edmund Delisser in his journal named both Nullarbor and Eucla for the first time.
A proposed new state of Auralia would have comprised the Goldfields, the western portion of the Nullarbor Plain and the port town of Esperance. Its capital would have been Kalgoorlie.
During the British nuclear tests at Maralinga in the 1950s, the Australian Government removed the Wangai people from their homeland. Since then, they have been awarded compensation, and many have returned to the general area. Others never left.
Some agricultural interests are on the fringe of the plain including the Rawlinna Station, the largest sheep station in the world, on the Western Australian side of the plain. The property has a short history compared to other properties of its type around Australia, having been established in 1962 by Hugh G. MacLachlan, of the South Australian pastoral family. An older property is Madura Station, situated closer to the coast; it has a size of and is also stocked with sheep. Madura was established prior to 1927; the extent of the property at that time was reported as.
In 2013, a huge area of the Nullarbor Plain, stretching almost from the Western Australian border to the Great Australian Bight, was proclaimed as the Nullarbor Wilderness Protection Area under the Wilderness Protection Act 1992, doubling the area of land in South Australia under environmental protection to. The area contains 390 species of plants and a large number of habitats for rare species of animals and birds.
Image:Nullarbor Plain Escarpment DSC04558.JPG|thumb|right|A road sign displaying the distance from Eucla and Ceduna.
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Geology and geography

The Nullarbor Plain is a former shallow seabed, as indicated by the presence of bryozoans, foraminifera, echinoids and red algae calcareous skeletons that make up the limestone. The region is also the location of "Nullarbor limestone" and it has a reputation as a significant karst region with Oligocene and Miocene cave formations.
The sequence within the limestone includes five formations:
  • the upper formation is the Nullarbor Limestone which is early middle Miocene in age;
  • the Mullamullang member of this formation is a paraconforming member, being separated by 5 million years;
  • the third member is the Abrakurrie Limestone that was formed in a central depression of the earlier formation; this is late Oligocene to Early Miocene in age and does not reach the edge of the plain;
  • the last two formations are conforming formations; the late Eocene Toolinna Limestone lies on the Wilsons Bluff Limestone which is mid- to late Eocene in age; and
  • the Toolinna Limestone does not cover the whole Nullarbor and is extant only in the extreme east beside the Abrakurrie formation which lies in a depression.
One theory is that the whole area was uplifted by crustal movements in the Miocene, and since then, erosion by wind and rain has reduced its thickness. The plain has most likely never had any major defining topographic features, resulting in the extremely flat terrain across the plain today.
According to Curtin University research published in 2023, "Nullarbor drastically shifted to dry conditions between 2.4 and 2.7 million years ago". Image:Highway sign, Nullarbor, 2017.jpg|thumb|Sign defining the edge of the plain at the western side.
In areas, the southern ocean blows through many caves, resulting in blowholes up to several hundred metres from the coast. The Murrawijinie Cave in South Australia is open to the public, but most of the Nullarbor Caves on the Western Australian side can only be visited and viewed with a permit from the Department of Parks and Wildlife.
The Nullarbor is known for extensive meteorite deposits, which are extremely well preserved in the arid climate. In particular, many meteorites have been discovered around Mundrabilla, some up to several tonnes in weight.
According to the USDA soil taxonomy system, the Nullarbor's soils are classified as mainly consisting of aridisols.

Limits

Frequently The Nullarbor is expanded in tourist literature and web-based material to loosely refer to all the land between Adelaide, South Australia and Perth, Western Australia. Through observing satellite images, the limits of the limestone formation of the plain can be seen to stretch from approximately west of the original Balladonia settlement to its easternmost limit a few kilometres west of the town of Ceduna.

Climate

The Nullarbor includes desert and semi-arid climate zones. Updated versions of the Köppen climate classifications, the plain most closely fits the Köppen BWk "cold desert" and BSk "cold semi-arid" taxons. While summer days can be scorching hot, with daytime temperatures close to, in winter nights frequently drop well below freezing. Close to the coast, temperatures are more moderate and more rain falls in the winter months, compared to the most inland parts of Australia. The mean annual rainfall at Cook is, with most rain falling between May and August. Summers are very dry, with rain falling mainly from sporadic storms; however, occasionally decaying tropical systems can cause heavier rain in the summer months. Temperatures on the plain have ranged from at the like-named Nullarbor, South Australia which is the fourth hottest recorded temperature in all of Australia, to at Eyre, which is the coldest recorded temperature in Western Australia.

Biogeography

The Nullarbor Plain constitutes a deserts and xeric shrublands ecoregion, called the Nullarbor Plains xeric shrublands by the World Wildlife Fund. The ecoregion is coterminous with the Nullarbor biogeographic region under the Interim Biogeographic Regionalisation for Australia. The ecoregion is bounded on the west and southwest by the Coolgardie woodlands ecoregion, on the north and northeast by the Great Victoria Desert, on the southeast by the Eyre and Yorke mallee, and on the south by the Great Australian Bight.

Flora

Vegetation in the area is primarily low saltbush and bluebush scrub.

Fauna

The fauna of the Nullarbor includes communities of crustaceans, spiders, and beetles adapted to the darkness of the Nullarbor Caves and the underground rivers and lakes that run through them. Mammals of the desert include the southern hairy-nosed wombat, which shelters from the hot sun by burrowing into the sands, as well as typical desert animals such as red kangaroos and dingoes. An elusive subspecies of the Australian masked owl unique to the Nullarbor is known to roost in the many caves on the plain. The grasslands of the Nullarbor are suitable for some sheep grazing and are also damaged by rabbits. The caves provide roosts to large colonies of wattled microbats, species Chalinolobus morio.

Protected areas

A 2017 assessment found that 62,317 km2, or 32%, of the ecoregion is in protected areas. Protected areas include:

Telegraph

The need for a communications link across the continent was the spur for the development of an east–west crossing. Once Eyre had proved that a link between South Australia and Western Australia was possible, efforts to connect them via telegraph began. In 1877, after two years of labour, the first messages were sent on the new telegraph line, boosted by eight repeater stations along the way. The line operated for about 50 years before being superseded, and remnants of it remain visible.