A mangrove is a shrub or small tree that grows in coastal saline or brackish water. The term is used for tropical coastal vegetation consisting of such species. Mangroves occur worldwide in the tropics and subtropics between latitudes 25° N and 25° S; the total mangrove forest area of the world in 2000 was 137,800 square kilometres, spanning 118 countries and territories. Mangroves are salt-tolerant trees called halophytes, are adapted to life in harsh coastal conditions, they contain a complex salt filtration system and complex root system to cope with salt water immersion and wave action. They are adapted to the low oxygen conditions of waterlogged mud; the word is used in at least three senses: most broadly to refer to the habitat and entire plant assemblage or mangal, for which the terms mangrove forest biome, mangrove swamp are used, to refer to all trees and large shrubs in the mangrove swamp, narrowly to refer to the mangrove family of plants, the Rhizophoraceae, or more just to mangrove trees of the genus Rhizophora.
The mangrove biome, or mangal, is a distinct saline woodland or shrubland habitat characterized by depositional coastal environments, where fine sediments collect in areas protected from high-energy wave action. The saline conditions tolerated by various mangrove species range from brackish water, through pure seawater, to water concentrated by evaporation to over twice the salinity of ocean seawater; the term "mangrove" comes to English from Spanish, is to originate from Guarani. It was earlier "mangrow", but this word was corrupted via folk etymology influence of the word "grove". Mangrove swamps are found in subtropical tidal areas. Areas where mangals occur include marine shorelines; the intertidal existence to which these trees are adapted represents the major limitation to the number of species able to thrive in their habitat. High tide brings in salt water, when the tide recedes, solar evaporation of the seawater in the soil leads to further increases in salinity; the return of tide can flush out these soils, bringing them back to salinity levels comparable to that of seawater.
At low tide, organisms are exposed to increases in temperature and desiccation, are cooled and flooded by the tide. Thus, for a plant to survive in this environment, it must tolerate broad ranges of salinity and moisture, as well as a number of other key environmental factors—thus only a select few species make up the mangrove tree community. About 110 species are considered "mangroves", in the sense of being a tree that grows in such a saline swamp, though only a few are from the mangrove plant genus, Rhizophora. However, a given mangrove swamp features only a small number of tree species, it is not uncommon for a mangrove forest in the Caribbean to feature only three or four tree species. For comparison, the tropical rainforest biome contains thousands of tree species, but this is not to say mangrove forests lack diversity. Though the trees themselves are few in species, the ecosystem that these trees create provides a home for a great variety of other species. Mangrove plants require a number of physiological adaptations to overcome the problems of anoxia, high salinity and frequent tidal inundation.
Each species has its own solutions to these problems. Small environmental variations within a mangal may lead to differing methods for coping with the environment. Therefore, the mix of species is determined by the tolerances of individual species to physical conditions, such as tidal inundation and salinity, but may be influenced by other factors, such as predation of plant seedlings by crabs. Once established, mangrove roots provide an oyster habitat and slow water flow, thereby enhancing sediment deposition in areas where it is occurring; the fine, anoxic sediments under mangroves act as sinks for a variety of heavy metals which colloidal particles in the sediments have scavenged from the water. Mangrove removal disturbs these underlying sediments creating problems of trace metal contamination of seawater and biota. Mangrove swamps protect coastal areas from erosion, storm surge, tsunamis; the mangroves' massive root systems are efficient at dissipating wave energy. They slow down tidal water enough so its sediment is deposited as the tide comes in, leaving all except fine particles when the tide ebbs.
In this way, mangroves build their own environments. Because of the uniqueness of mangrove ecosystems and the protection against erosion they provide, they are the object of conservation programs, including national biodiversity action plans. Mangrove swamps' effectiveness in terms of erosion control can sometimes be overstated. Wave energy is low in areas where mangroves grow, so their effect on erosion is measured over long periods, their capacity to limit high-energy wave erosion is in relation to events such as storm surges and tsunamis. The unique ecosystem found in the intricate mesh of mangrove roots offers a quiet marine region for young organisms. In areas where roots are permanently submerged, the organisms they host include algae, oysters and bryozoans, which all require a hard surface for anchoring while they filter feed. Shrimps and mud lobsters use the muddy bottoms as their home. Mangrove crabs munch on the mangrove leaves, adding nutrients to the mangal muds for other bottom feeders.
In at least some cases, export of carbon fixed in mangroves is imp
An estuary is a enclosed coastal body of brackish water with one or more rivers or streams flowing into it, with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments, they are subject both to marine influences—such as tides and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The mixing of sea water and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are classified according to their geomorphological features or to water-circulation patterns, they can have many different names, such as bays, lagoons, inlets, or sounds, although some of these water bodies do not meet the above definition of an estuary and may be saline.
The banks of many estuaries are amongst the most populated areas of the world, with about 60% of the world's population living along estuaries and the coast. As a result, many estuaries suffer degradation from a variety of factors including: sedimentation from soil erosion from deforestation and other poor farming practices; the word "estuary" is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus, meaning tide. There have been many definitions proposed to describe an estuary; the most accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, within which sea water is measurably diluted with freshwater derived from land drainage". However, this definition excludes a number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff.
This broad definition includes fjords, river mouths, tidal creeks. An estuary is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides; the sea water entering the estuary streams. The pattern of dilution varies between different estuaries and depends on the volume of fresh water, the tidal range, the extent of evaporation of the water in the estuary. Drowned river valleys are known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley; this is the most common type of estuary in temperate climates. Well-studied estuaries include the Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border; the width-to-depth ratio of these estuaries is large, appearing wedge-shaped in the inner part and broadening and deepening seaward. Water depths exceed 30 m.
Examples of this type of estuary in the U. S. are the Hudson River, Chesapeake Bay, Delaware Bay along the Mid-Atlantic coast, Galveston Bay and Tampa Bay along the Gulf Coast. Bar-built estuaries are found in place where the deposition of sediment has kept pace with rising sea level so that the estuaries are shallow and separated from the sea by sand spits or barrier islands, they are common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches. Formation of barrier beaches encloses the estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries develop on sloping plains located along tectonically stable edges of continents and marginal sea coasts, they are extensive along the Atlantic and Gulf coasts of the U. S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m. The barrier beaches that enclose bar-built estuaries have been developed in several ways: building up of offshore bars by wave action, in which sand from the sea floor is deposited in elongated bars parallel to the shoreline, reworking of sediment discharge from rivers by wave and wind action into beaches, overwash flats, dunes, engulfment of mainland beach ridges due to sea level rise and resulting in the breaching of the ridges and flooding of the coastal lowlands, forming shallow lagoons, elongation of barrier spits from the erosion of headlands due to the action of longshore currents, with the spits growing in the direction of the littoral drift.
Barrier beaches form in shallow water and are parallel to the shoreline, resulting in long, narrow estuaries. The average water depth is less than 5 m, exceeds 10 m. Examples of bar-built estuaries are Barnegat Bay, New Jersey. Fjords were formed where pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross s
The Coral Sea is a marginal sea of the South Pacific off the northeast coast of Australia, classified as an interim Australian bioregion. The Coral Sea extends 2,000 kilometres down the Australian northeast coast, it is bounded in the west by the east coast of Queensland, thereby including the Great Barrier Reef, in the east by Vanuatu and by New Caledonia, in the northeast by the southern extremity of the Solomon Islands. In the northwest, it reaches to the south coast of eastern New Guinea, thereby including the Gulf of Papua, it merges with the Tasman Sea in the south, with the Solomon Sea in the north and with the Pacific Ocean in the east. On the west, it is bounded by the mainland coast of Queensland, in the northwest, it connects with the Arafura Sea through the Torres Strait; the sea is characterised with frequent rains and tropical cyclones. It contains numerous islands and reefs, as well as the world's largest reef system, the Great Barrier Reef, declared a World Heritage Site by UNESCO in 1981.
All previous oil exploration projects were terminated at the GBR in 1975, fishing is restricted in many areas. The reefs and islands of the Coral Sea are rich in birds and aquatic life and are a popular tourist destination, both nationally and internationally. While the Great Barrier Reef with its islands and cays belong to Queensland, most reefs and islets east of it are part of the Coral Sea Islands Territory. In addition, some islands west of and belonging to New Caledonia are part of the Coral Sea Islands in a geographical sense, such as the Chesterfield Islands and Bellona Reefs; the International Hydrographic Organization defines the limits of the Coral Sea as follows: On the North. The South coast of New Guinea from the entrance to the Bensbach River to Gadogadoa Island near its Southeastern extreme, down this meridian to the 100 fathom line and thence along the Southern edges of Uluma Reef and those extending to the Eastward as far as the Southeast point of Lawik Reef off Tagula Island, thence a line to the Southern extreme of Rennell Island and from its Eastern point to Cape Surville, the Eastern extreme of San Cristobal Island, Solomons.
On the Northeast. From the Northernmost island of the Duff Islands, through these islands to their Southeastern extreme, thence a line to Méré Lava, Vanuatu Islands and down the Eastern coasts of the islands of this Group to Anatom Island in such a way that all the islands of these Groups, the straits separating them, are included in the Coral Sea. On the Southeast. A line from the Southeastern extreme of Anatom Island to Nokanhoui off the Southeast extreme of New Caledonia, thence through the East point of Middleton Reef to the Eastern extreme of Elizabeth Reef and down this meridian to Latitude 30° South. On the South; the parallel of 30° South to the Australian coast. On the West; the Eastern limit of the Arafura Sea and the East Coast of Australia as far south as Latitude 30° South. The Coral Sea basin was formed between 58 million and 48 million years ago when the Queensland continental shelf was uplifted, forming the Great Dividing Range, continental blocks subsided at the same time; the sea has been an important source of coral for the Great Barrier Reef, both during its formation and after sea level lowering.
The geological formation processes are still proceeding, as evidenced by the seismic activity. Several hundred earthquakes with the magnitude between 2 and 6 were recorded in the period 1866–2000 along the Queensland coast and in the Coral Sea. On 2 April 2007, the Solomon Islands were struck by a major earthquake followed by a several metres tall tsunami; the epicentre of this magnitude 8.1 earthquake was 349 km northwest of Honiara, at a depth of 10 kilometres. It was followed by more than 44 aftershocks of a magnitude greater; the resulting tsunami destroyed more than 900 homes. The sea received its name because of its numerous coral formations, they include the GBR, which extends about 2,000 km along the northeast coast of Australia and includes 2,900 individual reefs and 1000 islands. The Chesterfield Islands and Lihou Reef are the largest atolls of the Coral Sea. Major Coral Sea currents form a counter-clockwise gyro, it brings warm nutrient-poor waters from the Coral Sea down the east coast of Australia to the cool waters of the Tasman Sea.
This current is the strongest along the Australian coasts and transforms 30 million m3/s of water within a flow band of about 100 kilometres wide and 500 metres deep. The current is weakest around August; the major river flowing into the sea is the Burdekin River, which has its delta southeast of Townsville. Owing to the seasonal and annual variations in occurrence of cyclones and in precipitation, its annual discharge can vary more than 10 times between the two succeeding years. In particular, in the period 1920–1999, the average flow rate near the delta was below 1000 m3/s in 1923, 1931, 1939, 1969, 1982, 1985, 1987, 1993 and 1995; this irregul
Daintree National Park
The Daintree rainforest is a national park in Far North Queensland, Australia, 1,502 km northwest of Brisbane and 100 km northwest of Cairns. It is part of the Wet Tropics of Queensland. In 1988 it became a World Heritage Site; the park consists of two sections, with a settled agricultural area between them which includes the towns of Mossman and Daintree Village. One entrance to Daintree National Park is located south of the Daintree River at Mossman Gorge where a visitor centre has been built from where tourists take a shuttle bus to the gorge, where they can take a walk or a refreshing swim; the most spectacular and oldest part of the Daintree rain forest is north of the Daintree River. After crossing the river on an old fashioned cable ferry there is a range of boardwalks and untouched beaches to explore, the endangered cassowary can be encountered anywhere. Daintree National Park is valued because of its exceptional biodiversity, it contains significant habitat for prolific birdlife. The name is derived from the Daintree River, named by George Elphinstone Dalrymple, an early explorer of the area, after his friend Richard Daintree.
The Great Dividing Range is close to the coast in this region. This section covers 56,500 ha of inaccessible rainforests and mountain woodlands; the popular Mossman Gorge is located in the southern part of the park. Cape Tribulation lies in the park; the cape belonged to Cape Tribulation National Park from 1981 but was amalgamated into Daintree National Park in 1983. This section covers 17,000 ha including the coastal range and contains Australia's last extensive stands of lowland rainforest, it has extensive unspoiled beaches from Thornton beach to Cape Tribulation beach – fringed with the rare littoral rainforest. The Daintree river is the southern boundary for the region - reinforced by the need to take a cable ferry across the Daintree river. Much of the coastal flatlands to the south of the Alexandra range, in Cow Bay, were cleared for agriculture in the late 1800s with a major clearing push in the 1970s. A lot of this has been settled; the Daintree National Park's traditional owners are the Eastern Kuku Yalanji Aboriginal people.
Many of the natural features of the landscape hold spiritual significance for the traditional owners. One of these features is the location of the bouncing stones at Thornton Beach; the rocks here are hornfels, metamorphic rocks resulting from the effects of a major intrusion of granite that produced the coastal mountains. They are elastic, when bounced on the local rock pavement. Much of the national park is covered by tropical rainforest; the Greater Daintree Rainforest has existed continuously for more than 110 million years, making it the oldest existing rainforest. The persistence of this rainforest is believed to be a product of a fortuitous continental drift; the rainforests of the parent continent preserved its climate, so its original trees. Tree species, once thought to be long extinct, have only recently been discovered here; the park supports more than 430 bird species. The wompoo fruit-dove is one of six species of pigeon that live in the park as well as significant populations of the endangered cassowary, a flightless bird of substantial size.
The buff-breasted paradise kingfisher is a seasonal visitor. Mammals include the striped possum, Daintree River ringtail possum, brown bandicoot, long-nosed bandicoot, musky rat-kangaroo, Bennett’s tree kangaroo, swamp wallaby and short-beaked echidna. At least 23 species of reptile and 13 species of amphibian can be found in the park. Among the reptiles present are Boyd's forest dragon, eastern water dragon, chameleon gecko, northern leaf-tailed gecko, the scrub or amethystine python and the green and northern tree snakes. Frogs found in the park include the Australian lacelid, white-lipped treefrog, colourful-eyed treefrog and common mist frog; the introduced cane toad is present in the park. Protected areas of Queensland Media related to Daintree National Park at Wikimedia Commons
The Kuku Yalanji known as Gugu-Yalanji or Kokojelandji, are an Indigenous Australian people originating from the rainforest regions of Far North Queensland. The traditional language of the people was Guugu Yalandji, it has been comprehensively studied, with a dictionary produced by the Hershbergers and a grammar by Elizabeth Patz. The Kuku Yalanji, according to Norman Tindale, held 2,200 square miles of territory around the headwaters of the Palmer River, their land ran east from Palmerville station to Mount Lukin, stretched over the southern and western areas of the Dividing Range as far as the upper Mitchell River. Their eastern limits lay around east to Byerstown, they were present at Maytown. Kuku Yalanji lands began to be occupied extensively by white colonisers in 1877, after the government opened up their area to selection, as miners crowded into the area, where the Palmer River gold rush had been underway since news leaked out of a discovery of that mineral in June 1873.time. Within a year over 5,000 Europeans and 2,000 Chinese from Guangdong, crammed into the Palmer River site, until the sole preserve of Kuku Yalanji people, to work its riches.
Attempts made to uproot the people from their land were resisted, a Lutheran mission opened up on the Bloomfield River in 1886 failed within 16 years of its establishment. Century. Forced removals of some Kuku-Yalanji were undertaken again in the 1930s, with their relocation to missions at Daintree and Mossman; as late as 1957, a further attempt to relocate groups to a mission in Bloomfield took place. The gold rush lasted from 1873 to 1885, with the Palmer population of Chinese skyrocketing to some 17,000 by 1877, until the opportunities for quick takings began to dwindle, with most Europeans leaving by 1880, the Chinese numbers dropping drastically to 3,000. In response to this overwhelming invasion, the Kuku Yalanji set up a fierce resistance tantamount to guerilla warfare; the Kuku Yalanji were reduced to living in shanty towns on the outskirts of the areas which the foreign populations developed, developed skills for working in the new economy. In trading their services with the Chinese, they were paid in opium, which could be imported until 1906.
According to contemporary European observers appointed as protectors of Aborigines, such as Walter Roth and Archibald Meston, consumption of this drug in the form of opium ash mixed with water, accounted for thousands of native deaths, far more than those due to other introduced maladies such as venereal disease. Modern historians now consider that these early reports, like the bruited tales of the Kuku Yalanji hunting Chinese for cannibalistic feasting, whatever partial truth they contain functioned to assuage any guilt European settlers may have felt for their key role in the decimation of northern Queensland aboriginal communities. From 1897 to the 1960s, the Kuku Yalanji like other Aboriginal peoples faced the Government's paternalistic legislation that allowed for Aborigines to be placed under "protection" in attempt to preserve their culture; the Kuku Yalanji began concentrating around the Mossman Reserve around the time of World War II and the people in the Daintree region were forced to the northern bank of the Daintree River.
They were further subjected to more relocations by the government. Kuku Yalanji are now concentrated predominantly in Wujal Wujal; the Kuku Yalanji, believed to number some 3,000 people, constitute one of the "Bama Rainforest Peoples". They were reputedly related to the Wulpura rain forest dwellers on the plateau in the modern day Mount Windsor National Park. Survival was dependent on the exploitation of seasonal variation, it is believed that Kuku Yalanji lived in the rainforest region no than 4,000 years ago. It is known that they had high population density, lived in semi-permanent gunyahs, their staples for obtaining carbohydrates were the toxic seeds of Cycas media, which were leached of their poisonous compounds before cooking. They classified the annual climatic cycle into five seasons. Early reports wrote that the Kuku Yalanji were devoted to cannibalism, targeting in particular Chinese immigrants, whom they called kubara or miran bilin, it is not infrequent to encounter early accounts of the eating of parts of the dead, which however was a restricted practice related to ritual mortuary customs.
The vivid narrations of their killing their own women and children for eating to allay their hunger or of "feasting" on Chinese like "manna from heaven" in popular works like that of Hector Holthouse, are now considered wild exaggerations, since the actual evidence is skimpy. Christopher Anderson, who transcribed one account by an elderly initiated Kuku Yalanji man glosses the story by suggesting that:- Apart from the rare actual incidents human flesh consumption, the strong European belief in Aboriginal cannibalism in this area arose and persists today, I would argue, as an ideological mechanism: it states and reinforces the belief that Aborigines were less human or at the least were "uncivilized". Justified their removal from the land and their extermination; the Kuku-Yalanji people registered a Native Title Claim over parts of their traditional land in May 1995. Jessica Mauboy, an Australian R&B and pop recording artist and starred in the 2012 indigenous hit film The Sapphires. Pat O'Shane, a teacher, public servant and Aboriginal activist, she was Australia's first Aboriginal magistrate.
Tony Albert, contemporary artist, co-founder of artist collective PROPPA NOW "Cultur
Gold is a chemical element with symbol Au and atomic number 79, making it one of the higher atomic number elements that occur naturally. In its purest form, it is a bright reddish yellow, soft and ductile metal. Chemically, gold is a group 11 element, it is solid under standard conditions. Gold occurs in free elemental form, as nuggets or grains, in rocks, in veins, in alluvial deposits, it occurs in a solid solution series with the native element silver and naturally alloyed with copper and palladium. Less it occurs in minerals as gold compounds with tellurium. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloric acid, which forms a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term acid test. Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating.
Gold dissolves in mercury, forming amalgam alloys. A rare element, gold is a precious metal, used for coinage and other arts throughout recorded history. In the past, a gold standard was implemented as a monetary policy, but gold coins ceased to be minted as a circulating currency in the 1930s, the world gold standard was abandoned for a fiat currency system after 1971. A total of 186,700 tonnes of gold exists above ground, as of 2015; the world consumption of new gold produced is about 50% in jewelry, 40% in investments, 10% in industry. Gold's high malleability, resistance to corrosion and most other chemical reactions, conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices. Gold is used in infrared shielding, colored-glass production, gold leafing, tooth restoration. Certain gold salts are still used as anti-inflammatories in medicine; as of 2017, the world's largest gold producer by far was China with 440 tonnes per year.
Gold is the most malleable of all metals. It can be drawn into a monoatomic wire, stretched about twice before it breaks; such nanowires distort via formation and migration of dislocations and crystal twins without noticeable hardening. A single gram of gold can be beaten into a sheet of 1 square meter, an avoirdupois ounce into 300 square feet. Gold leaf can be beaten thin enough to become semi-transparent; the transmitted light appears greenish blue, because gold reflects yellow and red. Such semi-transparent sheets strongly reflect infrared light, making them useful as infrared shields in visors of heat-resistant suits, in sun-visors for spacesuits. Gold is a good conductor of electricity. Gold has a density of 19.3 g/cm3 identical to that of tungsten at 19.25 g/cm3. By comparison, the density of lead is 11.34 g/cm3, that of the densest element, osmium, is 22.588±0.015 g/cm3. Whereas most metals are gray or silvery white, gold is reddish-yellow; this color is determined by the frequency of plasma oscillations among the metal's valence electrons, in the ultraviolet range for most metals but in the visible range for gold due to relativistic effects affecting the orbitals around gold atoms.
Similar effects impart a golden hue to metallic caesium. Common colored gold alloys include the distinctive eighteen-karat rose gold created by the addition of copper. Alloys containing palladium or nickel are important in commercial jewelry as these produce white gold alloys. Fourteen-karat gold-copper alloy is nearly identical in color to certain bronze alloys, both may be used to produce police and other badges. White gold alloys can be made with nickel. Fourteen- and eighteen-karat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. Blue gold can be made by alloying with iron, purple gold can be made by alloying with aluminium. Less addition of manganese, aluminium and other elements can produce more unusual colors of gold for various applications. Colloidal gold, used by electron-microscopists, is red. Gold has only one stable isotope, 197Au, its only occurring isotope, so gold is both a mononuclidic and monoisotopic element. Thirty-six radioisotopes have been synthesized, ranging in atomic mass from 169 to 205.
The most stable of these is 195Au with a half-life of 186.1 days. The least stable is 171Au. Most of gold's radioisotopes with atomic masses below 197 decay by some combination of proton emission, α decay, β+ decay; the exceptions are 195Au, which decays by electron capture, 196Au, which decays most by electron capture with a minor β− decay path. All of gold's radioisotopes with atomic masses above 197 decay by β− decay. At least 32 nuclear isomers have been characterized, ranging in atomic mass from 170 to 200. Within that range, only 178Au, 180Au, 181Au, 182Au, 188Au do not have isomers. Gold's most stable isomer is 198m2Au with a half-life of 2.27 days. Gold's least stable isomer is 177m2Au with a half-life of only 7 ns. 184m1Au has three decay paths: β+ decay, isomeric
Great Dividing Range
The Great Dividing Range, or the Eastern Highlands, is Australia's most substantial mountain range and the third longest land-based range in the world. It stretches more than 3,500 kilometres from Dauan Island off the northeastern tip of Queensland, running the entire length of the eastern coastline through New South Wales into Victoria and turning west, before fading into the central plain at the Grampians in western Victoria; the width of the range varies from about 160 km to over 300 km. The Greater Blue Mountains Area, Gondwana Rainforests, Wet Tropics of Queensland World Heritage Areas are located in the range; the sharp rise between the coastal lowlands and the eastern uplands has affected Australia's climate due to orographic precipitation, these areas of highest relief have revealed an impressive gorge country. The Dividing Range does not consist of a single mountain range, it consists of a complex of mountain ranges, upland areas and escarpments with an ancient and complex geological history.
The physiographic division name for the landmass is called the East Australian Cordillera. In some places the terrain is flat, consisting of low hills; the highlands range from 300 to 1,600 metres in height. The mountains and plateaus, which consist of limestones, quartzite and dolomite, have been created by faulting and folding processes; the crest of the range is defined by the watershed or boundary between the drainage basins of rivers which drain directly eastward into the Pacific Ocean, or southward into Bass Strait, those rivers which drain into the Murray–Darling river system towards the west and south. In central Queensland, the rivers on the west side drain into Lake Eyre basin. In north Queensland, the rivers on the west side of the range drain towards the Gulf of Carpentaria; the higher and more rugged parts of the "range" do not form part of the crest of the range, but may be branches and offshoots from it. The term "Great Dividing Range" may refer to the watershed crest of the range, or to the entire upland complex including all of the hills and mountains between the east coast of Australia and the central plains and lowlands.
At some places it can be up to 400 km wide. Notable ranges and other features which form part of the range complex have their own distinctive names; the Great Dividing Range was formed during the Carboniferous period—over 300 million years ago—when Australia collided with what are now parts of South America and New Zealand. The range has experienced significant erosion since. For tens of thousands of years prior to British colonisation the ranges were home to various Aboriginal Australian nations and clans. Evidence remains in some places of their traditional way of life including decorated caves and trails used to travel between the coastal and inland regions. Many descendants of these nations still exist today and remain the traditional owners and custodians of their lands. After British colonisation in 1788, the ranges were an obstacle to exploration and settlement by the British settlers. Although not high, parts of the highlands were rugged. Crossing the Blue Mountains was challenging due to the mistaken idea that the creeks should be followed rather than the ridges, impenetrable, sandstone mountains.
Knowing that local Aboriginal people had established routes crossing the range and by making use of Aboriginal walking trails, a usable ridge-top route was discovered by Europeans directly westward from Sydney across the Blue Mountains to Bathurst by an expedition jointly led by Gregory Blaxland, William Lawson and William Charles Wentworth. Towns in the Blue Mountains were named after each of these men; this was the start of the development of the agricultural districts of inland New South Wales. A road was built to Blaxland by convicts within six months. Easier routes to inland New South Wales were discovered towards Goulburn to the southwest, westwards from Newcastle. Subsequent explorations were made across and around the ranges by Allan Cunningham, John Oxley, Hamilton Hume, Paul Edmund Strzelecki, Ludwig Leichhardt and Thomas Mitchell; these explorers were concerned with finding and appropriating good agricultural land. By the late 1830s the most fertile rangelands adjacent to the mountain ranges had been explored, appropriated from the traditional inhabitants and some settled.
These included the Gippsland and Riverina regions in the south, up to the Liverpool Plains and the Darling Downs in the north. Various road and railway routes were subsequently established through many parts of the ranges, although many areas remain remote to this day. For example, in eastern Victoria there is only one major road crossing the highlands from north to south, the Great Alpine Road. Parts of the highlands consisting of flat and, by Australian standards, well-watered land were developed for agricultural and pastoral uses; such areas include the Atherton Tableland and Darling Downs in Queensland, the Northern Tablelands, Southern Highlands and Southern Tablelands in New South Wales. Other parts of the highlands have been used for forestry. Many parts of the highlands which were not developed are now included in National Parks. All of mainland Australia's alpine areas, including its highest mountain, Mount Kosciuszko, are part of this range, called the Main Range; the highest areas in southern New South Wales and eastern Victoria are known as the Australian Alps.
The central core of the Great Dividing Range is dotted with hundreds of peaks and is surrounded by many smaller mountain ranges or spurs, vall