Granulite
Granulites are a class of high-grade metamorphic rocks of the granulite facies that have experienced high-temperature and moderate-pressure metamorphism. They are medium to coarse–grained and composed of feldspars sometimes associated with quartz and anhydrous ferromagnesian minerals, with granoblastic texture and gneissose to massive structure, they are of particular interest to geologists because many granulites represent samples of the deep continental crust. Some granulites experienced decompression from deep in the Earth to shallower crustal levels at high temperature; the minerals present in a granulite will vary depending on the parent rock of the granulite and the temperature and pressure conditions experienced during metamorphism. A common type of granulite found in high-grade metamorphic rocks of the continents contains pyroxene, plagioclase feldspar and accessory garnet and amphiboles. Both clinopyroxene and orthopyroxene may be present, in fact, the coexistence of clino- and orthopyroxene in a metabasite defines the granulite facies.
A granulite may be visually quite distinct with abundant small pink or red pyralspite garnets in a'granular' holocrystalline matrix. Concentrations of garnets, micas, or amphiboles may form along a linear pattern resembling gneiss or migmatite banding. Granulites form at crustal depths during regional metamorphism at high thermal gradients of greater than 30 °C/km. In continental crustal rocks, biotite may break down at high temperatures to form orthopyroxene + potassium feldspar + water, producing a granulite. Other possible minerals formed at dehydration melting conditions include sapphirine, spinel and osumilite; some assemblages such as sapphirine + quartz indicate high temperatures of greater than 900 °C. Some granulites may represent the residues of partial melting at extraction of felsic melts in variable amounts, in extreme cases represent rocks that all constituent minerals are anhydrous and thus look as if they did not melt at ultrahigh temperature conditions; therefore high temperatures of 900 to 1150 °C are necessary to produce the granulite-facies mineral assemblages.
Such high temperatures at crustal depths only can be delivered by upwelling of the asthenospheric mantle in continental rifting settings, which can cause the regional metamorphism at the high thermal gradients of greater than 30 °C/km. The granulite facies is determined by the lower temperature boundary of 700 +/− 50 °C and the pressure range of 2–15 kb; the most common mineral assemblage of granulite facies consists of antiperthitic plagioclase, alkali feldspar containing up to 50% albite and Al2O3-rich pyroxenes. Transition between amphibolite and granulite facies is defined by these reaction isograds: amphibole -> pyroxene + H2Obiotite -> K-feldspar + garnet + orthopyroxene + H2O. Hornblende granulite subfacies is a transitional coexistence region of anhydrous and hydrated ferromagnesian minerals, so the above-mentioned isograds mark the boundary with pyroxene granulite subfacies – facies with anhydrous mineral assemblages. Granulite is a name used by petrographers to designate two distinct classes of rocks.
According to the terminology of the French school it signifies a granite in which both kinds of mica occur, corresponds to the German Granit, or to the English muscovite biotite granite. This application has not been accepted generally. To the German petrologists granulite means a more or less banded fine-grained metamorphic rock, consisting of quartz and feldspar in small irregular crystals and also containing a fair number of minute, pale-red garnets. Among English and American geologists the term is employed in this sense; the granulites are closely allied to the gneisses, as they consist of nearly the same minerals, but they are finer-grained, have less perfect foliation, are more garnetiferous, have some special features of microscopic structure. In the rocks of this group the minerals, as seen in a microscopic slide, occur as small rounded grains forming a fitted mosaic; the individual crystals never have perfect form, indeed traces of it are rare. In some granulites they interlock, with irregular borders.
In most cases they are somewhat rounded with smaller grains between the larger. This is true of the quartz and feldspar which are the predominant minerals. Both muscovite and biotite may be present and vary in abundance; the garnets are generally larger than the above-mentioned ingredients, visible with the eye as pink spots on the broken surfaces of the rock. They are filled with enclosed grains of the other minerals; the feldspar of the granulites is orthoclase or cryptoperthite. Basic feldspars occur only rarely. Among accessory minerals, in addition to apatite and iron oxides, the following may be mentioned: hornblende, riebeckite and zoisite, sphene, sillimanite, hercynite, rutile and tourmaline. Though we may find larger grains of feldspar, quartz or epidote, it is more characteristic of these rocks that all the minerals
Northern Territory
The Northern Territory is an Australian territory in the central and central northern regions of Australia. It shares borders with Western Australia to the west, South Australia to the south, Queensland to the east. To the north, the territory looks out to the Timor Sea, the Arafura Sea and the Gulf of Carpentaria, including Western New Guinea and other Indonesian islands; the NT covers 1,349,129 square kilometres, making it the third-largest Australian federal division, the 11th-largest country subdivision in the world. It is sparsely populated, with a population of only 246,700, making it the least-populous of Australia's eight states and major territories, with fewer than half as many people as Tasmania; the archaeological history of the Northern Territory begins over 40,000 years ago when Indigenous Australians settled the region. Makassan traders began trading with the indigenous people of the Northern Territory for trepang from at least the 18th century onwards; the coast of the territory was first seen by Europeans in the 17th century.
The British were the first Europeans to attempt to settle the coastal regions. After three failed attempts to establish a settlement, success was achieved in 1869 with the establishment of a settlement at Port Darwin. Today the economy is based on tourism Kakadu National Park in the Top End and the Uluṟu-Kata Tjuṯa National Park in central Australia, mining; the capital and largest city is Darwin. The population is concentrated along the Stuart Highway; the other major settlements are Palmerston, Alice Springs, Katherine and Tennant Creek. Residents of the Northern Territory are known as "Territorians" and as "Northern Territorians", or more informally as "Top Enders" and "Centralians". Indigenous Australians have lived in the present area of the Northern Territory for an estimated 40,000 years, extensive seasonal trade links existed between them and the peoples of what is now Indonesia for at least five centuries. With the coming of the British, there were four early attempts to settle the harsh environment of the northern coast, of which three failed in starvation and despair.
The Northern Territory was part of colonial New South Wales from 1825 to 1863, except for a brief time from February to December 1846, when it was part of the short-lived colony of North Australia. It was part of South Australia from 1863 to 1911. Under the administration of colonial South Australia, the overland telegraph was constructed between 1870 and 1872. From its establishment in 1869 the Port of Darwin was the major Territory supply for many decades. A railway was built between Palmerston and Pine Creek between 1883 and 1889; the economic pattern of cattle raising and mining was established so that by 1911 there were 513,000 cattle. Victoria River Downs was at one time the largest cattle station in the world. Gold was found at Grove Hill in 1872 and at Pine Creek, Brocks Creek and copper was found at Daly River. On 1 January 1911, a decade after federation, the Northern Territory was separated from South Australia and transferred to federal control. Alfred Deakin opined at this time "To me the question has been not so much commercial as national, second and last.
Either we must accomplish the peopling of the northern territory or submit to its transfer to some other nation." In late 1912 there was growing sentiment. The names "Kingsland", "Centralia" and "Territoria" were proposed with Kingsland becoming the preferred choice in 1913. However, the name change never went ahead. For a brief time between 1927 and 1931 the Northern Territory was divided into North Australia and Central Australia at the 20th parallel of South latitude. Soon after this time, parts of the Northern Territory were considered in the Kimberley Plan as a possible site for the establishment of a Jewish Homeland, understandably considered the "Unpromised Land". During World War II, most of the Top End was placed under military government; this is the only time since Federation that part of an Australian state or territory has been under military control. After the war, control for the entire area was handed back to the Commonwealth; the Bombing of Darwin occurred on 19 February 1942. It was the largest single attack mounted by a foreign power on Australia.
Evidence of Darwin's World War II history is found at a variety of preserved sites in and around the city, including ammunition bunkers, oil tunnels and museums. The port was damaged in the 1942 Japanese air raids, it was subsequently restored. In the late 1960s improved roads in adjoining States linking with the territory, port delays and rapid economic development led to uncertainty in port and regional infrastructure development; as a result of the Commission of Enquiry established by the Administrator, port working arrangements were changed, berth investment deferred and a port masterplan prepared. Extension of rail transport was not considered because of low freight volumes. Indigenous Australians had struggled for rights to fair wages and land. An important event in this struggle was the strike and walk off by the Gurindji people at Wave Hill Cattle Station in 1966; the federal government of Gough Whitlam set up the Woodward Royal Commission in February 1973, which set to enquire into how land rights might be achieved in the Northern Territory.
Justice Woodward's first report in July 1973 recommended that a Central Land Council and a Northern Land Council be established to present to him the views of
Sedimentary rock
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of small particules and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. Sedimentation is the collective name for processes; the particles that form a sedimentary rock are called sediment, may be composed of geological detritus or biological detritus. Before being deposited, the geological detritus was formed by weathering and erosion from the source area, transported to the place of deposition by water, ice, mass movement or glaciers, which are called agents of denudation. Biological detritus was formed by bodies and parts of dead aquatic organisms, as well as their fecal mass, suspended in water and piling up on the floor of water bodies. Sedimentation may occur as dissolved minerals precipitate from water solution; the sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 8% of the total volume of the crust.
Sedimentary rocks are only a thin veneer over a crust consisting of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata; the study of sedimentary rocks and rock strata provides information about the subsurface, useful for civil engineering, for example in the construction of roads, tunnels, canals or other structures. Sedimentary rocks are important sources of natural resources like coal, fossil fuels, drinking water or ores; the study of the sequence of sedimentary rock strata is the main source for an understanding of the Earth's history, including palaeogeography and the history of life. The scientific discipline that studies the properties and origin of sedimentary rocks is called sedimentology. Sedimentology is part of both geology and physical geography and overlaps with other disciplines in the Earth sciences, such as pedology, geomorphology and structural geology. Sedimentary rocks have been found on Mars. Sedimentary rocks can be subdivided into four groups based on the processes responsible for their formation: clastic sedimentary rocks, biochemical sedimentary rocks, chemical sedimentary rocks, a fourth category for "other" sedimentary rocks formed by impacts and other minor processes.
Clastic sedimentary rocks are composed of other rock fragments that were cemented by silicate minerals. Clastic rocks are composed of quartz, rock fragments, clay minerals, mica. Clastic sedimentary rocks, are subdivided according to the dominant particle size. Most geologists use the Udden-Wentworth grain size scale and divide unconsolidated sediment into three fractions: gravel and mud; the classification of clastic sedimentary rocks parallels this scheme. This tripartite subdivision is mirrored by the broad categories of rudites and lutites in older literature; the subdivision of these three broad categories is based on differences in clast shape, grain size or texture. Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel. Sandstone classification schemes vary but most geologists have adopted the Dott scheme, which uses the relative abundance of quartz and lithic framework grains and the abundance of a muddy matrix between the larger grains.
Composition of framework grains The relative abundance of sand-sized framework grains determines the first word in a sandstone name. Naming depends on the dominance of the three most abundant components quartz, feldspar, or the lithic fragments that originated from other rocks. All other minerals are considered accessories and not used in the naming of the rock, regardless of abundance. Quartz sandstones have >90% quartz grains Feldspathic sandstones have <90% quartz grains and more feldspar grains than lithic grains Lithic sandstones have <90% quartz grains and more lithic grains than feldspar grainsAbundance of muddy matrix material between sand grains When sand-sized particles are deposited, the space between the grains either remains open or is filled with mud. "Clean" sandstones with open pore space are called arenites. Muddy sandstones with abundant muddy matrix are called wackes. Six sandstone names are possible using the descriptors for grain composition and the amount of matrix. For example, a quartz arenite would be composed of quartz grains and have little or no clayey matrix between the grains, a lithic wacke would have abundant lithic grains and abundant muddy matrix, etc.
Although the Dott classification scheme is used by sedimentologists, common names like greywacke and quartz sandstone are still used by non-specialists and in popular literature. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles; these fine-grained particles are transported by turbulent flow in water or air, deposited as the flow calms and the particles settle out of suspension. Most authors presently
Granite
Granite is a common type of felsic intrusive igneous rock, granular and phaneritic in texture. Granites can be predominantly white, pink, or gray depending on their mineralogy; the word "granite" comes from the Latin granum, a grain, in reference to the coarse-grained structure of such a holocrystalline rock. Speaking, granite is an igneous rock with between 20% and 60% quartz by volume, at least 35% of the total feldspar consisting of alkali feldspar, although the term "granite" is used to refer to a wider range of coarse-grained igneous rocks containing quartz and feldspar; the term "granitic" means granite-like and is applied to granite and a group of intrusive igneous rocks with similar textures and slight variations in composition and origin. These rocks consist of feldspar, quartz and amphibole minerals, which form an interlocking, somewhat equigranular matrix of feldspar and quartz with scattered darker biotite mica and amphibole peppering the lighter color minerals; some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic.
A granitic rock with a porphyritic texture is known as a granite porphyry. Granitoid is a descriptive field term for lighter-colored, coarse-grained igneous rocks. Petrographic examination is required for identification of specific types of granitoids; the extrusive igneous rock equivalent of granite is rhyolite. Granite is nearly always massive and tough; these properties have made granite a widespread construction stone throughout human history. The average density of granite is between 2.65 and 2.75 g/cm3, its compressive strength lies above 200 MPa, its viscosity near STP is 3–6·1019 Pa·s. The melting temperature of dry granite at ambient pressure is 1215–1260 °C. Granite has poor primary permeability overall, but strong secondary permeability through cracks and fractures if they are present. Granite is classified according to the QAPF diagram for coarse grained plutonic rocks and is named according to the percentage of quartz, alkali feldspar and plagioclase feldspar on the A-Q-P half of the diagram.
True granite contains both alkali feldspars. When a granitoid is devoid or nearly devoid of plagioclase, the rock is referred to as alkali feldspar granite; when a granitoid contains less than 10% orthoclase, it is called tonalite. A granite containing both muscovite and biotite micas is called two-mica granite. Two-mica granites are high in potassium and low in plagioclase, are S-type granites or A-type granites. A worldwide average of the chemical composition of granite, by weight percent, based on 2485 analyses: Granite containing rock is distributed throughout the continental crust. Much of it was intruded during the Precambrian age. Outcrops of granite tend to form rounded massifs. Granites sometimes occur in circular depressions surrounded by a range of hills, formed by the metamorphic aureole or hornfels. Granite occurs as small, less than 100 km2 stock masses and in batholiths that are associated with orogenic mountain ranges. Small dikes of granitic composition called aplites are associated with the margins of granitic intrusions.
In some locations coarse-grained pegmatite masses occur with granite. Granite is more common in continental crust than in oceanic crust, they are crystallized from felsic melts which are less dense than mafic rocks and thus tend to ascend toward the surface. In contrast, mafic rocks, either basalts or gabbros, once metamorphosed at eclogite facies, tend to sink into the mantle beneath the Moho. Granitoids have crystallized from felsic magmas that have compositions near a eutectic point. Magmas are composed of minerals in variable abundances. Traditionally, magmatic minerals are crystallized from the melts that have separated from their parental rocks and thus are evolved because of igneous differentiation. If a granite has a cooling process, it has the potential to form larger crystals. There are peritectic and residual minerals in granitic magmas. Peritectic minerals are generated through peritectic reactions, whereas residual minerals are inherited from parental rocks. In either case, magmas will evolve to the eutectic for crystallization upon cooling.
Anatectic melts are produced by peritectic reactions, but they are much less evolved than magmatic melts because they have not separated from their parental rocks. The composition of anatectic melts may change toward the magmatic melts through high-degree fractional crystallization. Fractional crystallisation serves to reduce a melt in iron, titanium and sodium, enrich the melt in potassium and silicon – alkali feldspar and quartz, are two of the defining constituents of granite; this process operates regardless of the origin of parental magmas to granites, regardless of their chemistry. The composition and origin of any magma that differentiates into granite leave certain petrological evidence as to what the granite's parental rock was; the final texture and composition of a granite are distinctive as to its parental rock. For instance, a granite, derived from partial melting of meta
Ernest Giles
William Ernest Powell Giles, best known as Ernest Giles, was an Australian explorer who led five major expeditions in central Australia. Ernest Giles was born in Bristol, son of William Giles, a merchant, Jane Elizabeth, née Powell. Giles was educated at Christ's Hospital school, London. In 1850, at the age of 15, he emigrated to Australia, joining his parents, took up residence in Adelaide, South Australia. In 1852 Giles went to the Victorian goldfields became a clerk at the Post Office in Melbourne, at the County Court. Soon tiring of town life Giles went to the back country and obtained valuable experience as a bushman. In 1865, he explored north-west of the Darling River in the Yancannia Range looking for pastoral country and land capable of cultivating hemp, as it was valuable for rope at the time. Giles did not attempt an organised expedition until 1872, when with two other men he left Chambers Pillar, South Australia, on 22 August and traversed much untrodden country to the north-west and west.
Finding their way barred by Lake Amadeus and that their horses were getting weak, a return was made to the Finke River and to Charlotte Waters and Adelaide, where Giles arrived in January 1873. Giles looked upon his expedition as a failure, but he had done well considering the size and equipment of his party. Giles' friend Baron; the services of William Tietkens as first assistant were obtained, with two other men a start was made on 4 August 1873. The journey began south from the previous expedition and from the Alberga River a western course was traversed. A month in the Musgrave Ranges a fine running river was found and named the Ferdinand and by 3 October 1873 the party was approaching longitude 128 East; the country was dry and though tested in various directions it was a constant struggle to get enough water to keep the horses going. Early in November, having passed longitude 126, a partial return was made and on 20 December 1873 the neighbourhood of Mount Scott was reached. A turn to the north and west was made and the farthest westerly point was reached on 23 April 1874.
Giles and one of the men, Alfred Gibson, had been scouting ahead. Giles gave him his own horse with instructions to obtain assistance. Giles made his way back to their depot on foot in eight days completely exhausted, to find that Gibson had not reached the camp. A search was made for him for several days without success; the stores were finished, nothing further could be done, on 21 May 1874 the return journey began. Giles named the desert Gibson Desert after his companion. On 24 June 1874 they were on a good track to the Finke River and on 13 July 1874 Charlotte Waters was reached. Giles had again failed to cross the continent, but in the circumstances all had been done, possible. Giles was the first European to see the rock formations named The Olgas, now known by the Aboriginal name Kata Tjuta, Lake Amadeus, he had wanted to name these Mt Mueller and Lake Ferdinand to honour his benefactor Baron Ferdinand von Mueller, however Mueller prevailed on him to instead honour the King Amadeus of Spain and Queen Olga of Württemberg.
Giles discovered Uluru, but was beaten to the claim by a competing explorer, William Gosse. Early in 1875 Giles prepared his diaries for publication under the title Geographic Travels in Central Australia, on 13 March 1875, with the generous help of Sir Thomas Elder, he began his third expedition. Proceeding to the north from Fowler's Bay the country was found to be dry. Retracing his steps Giles turned east, going round the north side of Lake Torrens reached Elder's station at Beltana. There the preparations for his fourth journey were made, with Tietkens again his lieutenant, with what Giles had always wanted, a caravan of camels, a start was made on 6 May. Port Augusta was reached on 23 May and, after taking a northerly course to clear the lakes, a westerly course was followed; some water was carried, the party was saved the continual excursions in search of water for horses that had caused so much difficulty during previous expeditions. Towards the end of September over 323 miles had been covered in 17 days without finding water, when on 25 September an Aboriginal man known as Tommy found an abundant supply in a small hollow between sand dunes at Queen Victoria Spring, the party was saved.
After a rest of nine days the journey was resumed on 6 October the course being still west. Ten days the expedition was attacked by a large body of Aborigines and Giles was compelled to fire on them. On 4 November they met a white stockman at Tootra out-camp, east of Bindi Bindi, their course was west to Walebing Station south-west and on 11 November they arrived at New Norcia where they were welcomed by Bishop Salvado. On 17 November 1875 the party arrived at Guildford and Perth the next day, where they received an enthusiastic reception. Giles stayed for two months at Perth. Tietkens and Jess Young, another member of the expedition, went back to Adelaide by sea, on 13 January 1876 Giles began the return journey taking a course about 400 miles north of the last journey, he arrived at Adelaide in September 1876 after a good journey during which the camels were found to be invaluable. Giles worked as a land classifier in the Western District of Victoria from 1877–79. In 1880 he published The Journal of a Forgotten Expedition, it being an account of his second and third expeditions in 1889 appeared Australia
Orthoclase
Orthoclase, or orthoclase feldspar, is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture," because its two cleavage planes are at right angles to each other, it is a type of potassium feldspar known as K-feldspar. The gem known as moonstone is composed of orthoclase. Orthoclase is a common constituent of most granites and other felsic igneous rocks and forms huge crystals and masses in pegmatite; the pure potassium endmember of orthoclase forms a solid solution with albite, the sodium endmember, of plagioclase. While cooling within the earth, sodium-rich albite lamellae form by exsolution, enriching the remaining orthoclase with potassium; the resulting intergrowth of the two feldspars is called perthite. The higher-temperature polymorph of KAlSi3O8 is sanidine. Sanidine is common in cooled volcanic rocks such as obsidian and felsic pyroclastic rocks, is notably found in trachytes of the Drachenfels, Germany; the lower-temperature polymorph of KAlSi3O8 is microcline.
Adularia is a low temperature form of either microcline or orthoclase reported from the low temperature hydrothermal deposits in the Adula Alps of Switzerland. It was first described by Ermenegildo Pini in 1781; the optical effect of adularescence in moonstone is due to adularia. The largest documented single crystal of orthoclase was found in the Ural mountains in Russia, it weighed ~ 100 tons. Together with the other potassium feldspars, orthoclase is a common raw material for the manufacture of some glasses and some ceramics such as porcelain, as a constituent of scouring powder; some intergrowths of orthoclase and albite have an attractive pale luster and are called moonstone when used in jewellery. Most moonstones are translucent and white, although grey and peach-colored varieties occur. In gemology, their luster is called adularescence and is described as creamy or silvery white with a "billowy" quality, it is the state gem of Florida. The gemstone called rainbow moonstone is more properly a colorless form of labradorite and can be distinguished from "true" moonstone by its greater transparency and play of color, although their value and durability do not differ.
Orthoclase is one of the ten defining minerals of the Mohs scale of mineral hardness, on which it is listed as having a hardness of 6. NASA's Curiosity Rover discovery of high levels of orthoclase in Martian sandstones suggested that some Martian rocks may have experienced complex geological processing, such as repeated melting. Minerals portal List of minerals
Stuart Highway
Stuart Highway is one of Australia's major highways. It runs from Darwin, Northern Territory, in the north, via Tennant Creek and Alice Springs, to Port Augusta, South Australia, in the south – a distance of 2,834 km, its northern and southern extremities are segments of Australia's Highway 1. The principal north-south route through the central interior of mainland Australia, the highway is referred to as "The Track"; the highway is named after Scottish explorer John McDouall Stuart, the first European to cross Australia from south to north. The highway approximates the route. Stuart Highway runs from Darwin, Northern Territory, in the north, via Tennant Creek and Alice Springs, to Port Augusta, South Australia, in the south – a distance of 2,834 km; the Royal Flying Doctor Service uses the highway as an emergency landing strip and sections of the highway are signed to that effect. These sections of highway have been specially selected and prepared for the landing of aircraft which only takes place after the piece of road has been closed by the police.
There are petrol and other facilities available at reasonable intervals and more frequent rest stops. Some of the rest stops are located at scenic points with information boards, but others are little more than a picnic table and a rubbish bin in an otherwise deserted area; the Northern Territory section of the Stuart Highway starts from the edge of the Darwin Central Business District at Daly Street and continues as a dual-carriageway to the Arnhem Highway in Howard Springs. The highway continues 317 km south passing the Kakadu Highway to the Victoria Highway at Katherine. At Daly Waters, the route number changes from National Highway 1 to National Highway 87; the highway continues 673 km south passing the Roper Highway, the Carpentaria Highway and the Buchanan Highway to the Barkly Highway at Tennant Creek. The highway continues 508 km south into Alice Springs passing the Plenty Highway, it passes through the Macdonnell Ranges and crosses the South Australia/Northern Territory border south of Kulgera.
The highway was only sealed in February 1987 as part of the Australian Bicentenary roadworks programme. There are no police patrolling the majority of this remote highway and until the end of 2006 there was no speed limit outside towns and other built-up areas on the Northern Territory part; the bulk of the Northern Territory's population not living in Darwin lies along its track. At the Northern Territory/South Australia border the route number changes from 87 to National Highway A87; the Stuart Highway passes through the Far North region to Port Augusta. The highway passes through the Woomera Prohibited Area; the highway continues south-east towards Adelaide. John McDouall Stuart led the first successful expedition to traverse the Australian mainland from south to north and return, through the centre of the continent, in 1861–1862. In 1871-72 the Australian Overland Telegraph Line was constructed along Stuart's route; the principal road from Port Augusta to Darwin was established on a similar route.
A track developed along the route of the telegraph, by 1888 the road between Adelaide and Alice Springs was well known. Several wells along the route provided water, although these could run dry or be contaminated by dead animals, resulting in sections as long as 144 miles without water; the route was traversed by motor vehicles in the 1920s. While passable, sections of the road could be sandy, washed away in the winter, or rugged with boulders. Several creek crossings were required. North of Alice Springs the road was in comparatively good condition, with sections allowing speeds of up to 50 miles per hour. With the onset of World War II, supply roads leading to the north of the country were considered vital by the federal government. A central north–south highway was planned to connect the railheads at Alice Springs and Birdum, with surveying completed in August 1940; the task of constructing the highway was split between the Main Roads Departments of three states, to ensure completion before the next wet season.
New South Wales would construct the northern section of 91 miles, Queensland the central section of 90 miles, South Australia the southern section of 131 miles. The Alice Springs–Birdum road was completed by December 1940, – upgraded from an impassable track to an all-weather sealed highway that could cope with heavy military traffic; the 306-mile highway was built in under than 90 days. In one week, 11 miles was constructed, claimed to be a world record; the new highway, in conjunction with the railways at either end, reduced the impact of Darwin's isolation. Quick and efficient movement of military equipment and troop was possible, with the road remaining open throughout the wet season. By March 1941, military authorities advocated extending the Alice Springs–Birdum road to Darwin. During the wet season, the road north of Birdum was impassable, which meant that a single railway line was the only connection through to Darwin. Construction was underway by October 1941, once again at a fast pace in an attempt to finish before the next wet season.
The road was nearing completion in July 1942. There was no absolute speed limit in the Northern Territory before 1 January 2007 but maximum speed limits are now posted on some road sections. Drivers were required to drive at a safe speed to suit the conditions. Thus, the Northern Territory section of the Stuart Highway had no speed limits at all; the Northern Territory traffic laws were updated from 1 January
