Geologically the Australian state of New South Wales consists of seven main regions: Lachlan Fold Belt, the

Hunter-Bowen Orogeny The Hunter-Bowen Orogeny was a significant arc accretion event in the Permian and Triassic periods affecting approximately 2,500 km of the Australian continental margin. The Hunter-Bowen Orogeny occurred in two main phases, a Permian accreti ...

or New England Orogen (NEO), the Delamerian Orogeny, the

Clarence Moreton Basin The Clarence Moreton Basin is a Mesozoic sedimentary basin on the easternmost part of the Australian continent. It is located in the far north east of the state of New South Wales around Lismore and Grafton and in the south east corner of Q ...

, the

Great Artesian Basin The Great Artesian Basin (GAB), located in Australia, is the largest and deepest artesian basin in the world, stretching over , with measured water temperatures ranging from . The basin provides the only source of fresh water through much of ...

, the

Sydney Basin The Sydney Basin is an interim Australian bioregion and is both a structural entity and a depositional area, now preserved on the east coast of New South Wales, Australia and with some of its eastern side now subsided beneath the Tasman Sea ...

, and the

Murray Basin The Murray Basin is a Cenozoic sedimentary basin in south eastern Australia. The basin is only shallow, but extends into New South Wales, Victoria and South Australia. It takes its name from the Murray River which traverses the Basin from ...

. There are a few other sedimentary basins, the Great Artesian Basin can be broken into the Eromanga Basin in the west and the

Surat Basin The Surat Basin is a geological basin in eastern Australia. It is part of the Great Artesian Basin drainage basin of Australia. The Surat Basin extends across an area of 270,000 square kilometres and the southern third of the basin occupies a lar ...

to the east. The Sydney Basin extends north into the Gunnedah Basin, which goes even further north into the

Bowen Basin The Bowen Basin contains the largest coal reserves in Australia. This major coal-producing region contains one of the world's largest deposits of bituminous coal. The Basin contains much of the known Permian coal resources in Queensland inclu ...

which extends into Queensland, under the Surat Basin. The New England Orogen has a few small Basins included, such as the Lorne Basin, the Myall Syncline, and Gloucester Basin. The Oaklands Basin is in the south of the state under the Murray Basin. The Darling Basin is in the state's west, but mostly covered by the Murray Basin. Gilgandra Sub-Basin and Paka Tank Trough are potential places for coal and gas. New South Wales is home to some important mining operations including

Broken Hill Broken Hill is an inland mining city in the far west of outback New South Wales, Australia. It is near the border with South Australia on the crossing of the Barrier Highway (A32) and the Silver City Highway (B79), in the Barrier Range. It ...

and coal mining and burning in the Hunter and Illawarra.

Delamerian orogeny

Lachlan Fold Belt

Rocks from the Lachlan Fold Belt are exposed through the south east and central parts of NSW, and underlie the

and the Sydney and Murray Basins at depth. The region is currently 1000 km wide, but was originally 2000 to 3000 km. The Lachlan Fold Belt was formed in the Middle Paleozoic from 450 to 340 Mya. It lies on a basement of

Cambrian The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago ...

oceanic floor, however, most of this has been subducted leaving the sediment veneer scraped off in chevron folds. It was compressed as the Pacific plate subducted beneath the Australian continent margin. Over time the hinge point, at which the ocean bed was bent down, changed to be more out to the east, and additional ocean bed sediment was added to the continent. This also means that there is a failed subduction zone extending through New South Wales. The

Australian Capital Territory The Australian Capital Territory (commonly abbreviated as ACT), known as the Federal Capital Territory (FCT) until 1938, is a landlocked federal territory of Australia containing the national capital Canberra and some surrounding township#Aust ...

is embedded in New South Wales in the Lachlan Fold Belt. The Narooma Terrane is another terrane abutted on the southeast corner of New South Wales which can be considered as a component of the Lachlan Fold Belt.

Hunter-Bowen orogeny

The Hunter-Bowen orogeny also known as the New England Orogen contains rocks from Late

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ...

to early

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

times. It was formed as an arc-forearc zone as the

Pacific Plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and I ...

was subducted to the west.

Darling and Barka Basins

The Darling basin formed in the very early

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wh ...

. Stretching the crust led to the formation of basins such as the Cobar Basin, Mount Hope Trough, Melrose Trough and Rast Trough. Where stretching was less, shelves were formed instead: Kopyje Shelf, Mouramba Shelf, Walters Range Shelf and Winduck Shelf. The Cobar Supergroup is the term used for the infill in these shelves and troughs which consisted of sediment and volcanics. The deeper basins included

turbidite A turbidite is the geologic deposit of a turbidity current, which is a type of amalgamation of fluidal and sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean. Sequencing Turbidites wer ...

s. Felsic volcanic material was also erupted in the Rast and Mount Hope Troughs. The Florida, Babinda, Majuba and Mineral Hill Volcanics are found on the East side of the Kopyje Shelf. Most of the sediment however is quartz sand. Subsequently in the early Devonian the basin content was pushed back up, and the Mulga Downs Group was deposited by rivers up until the

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferou ...

Period. This formed the Barka Basin. Rock from this group is mostly quartz sandstone, with a small amount of siltstone.

Sydney Basin

The Sydney Basin consists of

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleo ...

and

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest per ...

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

s stretching from Newcastle to

Batemans Bay Batemans Bay is a town on the South Coast region of the state of New South Wales, Australia. Batemans Bay is administered by the Eurobodalla Shire council. The town is situated on the shores of an estuary formed where the Clyde River meets th ...

. The land component covers 44000 km², but there is another 5000 km² underwater on the continental shelf. The basement consists of the Lachlan Fold Belt, and the New England Fold Belt is found to the north across the Hunter Thrust. It is a

foreland basin A foreland basin is a structural basin that develops adjacent and parallel to a mountain belt. Foreland basins form because the immense mass created by crustal thickening associated with the evolution of a mountain belt causes the lithosphere ...

, likely to be formed by compression loading. The first rocks formed in the

were the Dalwood Group and lower Shoalhaven Group. Material for this came from basaltic volcanoes to the north in the Hunter region. The Greta Coal Measures then formed in the north side in an alluvial fan from the mountains of the New England Orogen. The basin sank lower and sea water came much further inland, covering the Permian sediments and the basement further west, and the Maitland Group and upper Shoalhaven Group were deposited. The Muree/Nowra Sandstone formed in the centre of the basin. In the next stage the Hunter – Bowen Orogeny cause faulting and folding on the north side of the basin. In the Late Permian river and delta deposition formed the Tomago and Whittingham Coal Measures in the north. But deepening seawater formed the Kulnura Marine Tongue and Bulga Formation. In the southern part of the basin a delta formed the lower Illawarra Coal Measures. The Erins Vale Formation interrupts this. Marine transgression formed Dempsey Formation, Denman Formation, Bargo Claystone, and Ball Bone Formation. Beach deposition then formed Waratah/Watts Sandstone and the Darkes Forest Sandstone and Angus Place Sandstone. Over the beach land formed again with the Newcastle and Wollombi Coal Measures in the north, and upper Illawarra Coal Measures in the south. Early in the

the New England Fold Belt was uplifted and an alluvial flood plain formed the Narrabeen group. The Bald Hill Claystone, which is a redbed containing

laterite Laterite is both a soil and a rock type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by ...

was formed by weathering of the Gerringong Volcanics. The

Hawkesbury sandstone Sydney sandstone is the common name for Sydney Basin Hawkesbury Sandstone, one variety of which is historically known as Yellowblock, and also as "yellow gold" a sedimentary rock named after the Hawkesbury River north of Sydney, where this ...

is the prominent rock found in Sydney, and also forming the top of escarpments in the area, such as the Illawarra escarpment. This is overlain by the fine sandstone of the Mittagong Formation and the Wianamatta shale. The basin was later buried under 1 to 4 km of

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

and

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

sediments. The

Tasman Sea The Tasman Sea (Māori: ''Te Tai-o-Rēhua'', ) is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about across and about from north to south. The sea was named after the Dutch explorer ...

formed by rifting and underplating of the basin may have happened in

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ag ...

times. This resulted in the upper sediment being completely eroded off.

Great Artesian Basin

Part of the

is along the northern border of New South Wales and also extends north into Queensland. This is also known as Surat Basin. It occupies one fifth of the state of New South Wales. The eastern border extends from

Bebo Bebo ( ) was an American social networking website that originally operated from 2005 until its bankruptcy in 2013 and relaunched in February 2021. The site relaunched several times after its bankruptcy with a number of short-lived offerings, ...

Narrabri Narrabri ( ) is a locality and seat of Narrabri Shire local government area in the North West Slopes, New South Wales, Australia on the Namoi River, northwest of Sydney. It sits on the junction of the Kamilaroi Highway and the Newell Highway. ...

Murrurundi Murrurundi( ), is a rural town located in the Upper Hunter Shire, in the Upper Hunter region of New South Wales, Australia. Murrurundi is situated northwest by road from Newcastle and north from Sydney. At the the town had a population of ...

to Dunedoo to

Narromine Narromine ( /næroʊmaɪn/) is a rural Australian town located approximately 40 kilometres (25 mi) west of Dubbo in the Orana region of New South Wales. The town is at the centre of Narromine Shire. The 2016 census recorded a population o ...

. The basin was formed in the

and

periods.M. C. Hind and R. J. Helby: ''Geology of New South Wales'' pages 481–497 The oldest Jurassic rocks in the basin are found in the northeast near the Queensland border. They are called Precipice Sandstone, Evergreen Shale and Boxvale Sandstone, Hutton Sandstone from

Pliensbachian The Pliensbachian is an age (geology), age of the geologic timescale and stage (stratigraphy), stage in the stratigraphic column. It is part of the Early Jurassic, Early or Lower Jurassic epoch (geology), Epoch or series (stratigraphy), Series an ...

Aalenian The Aalenian () is a subdivision of the Middle Jurassic Epoch/Series of the geologic timescale that extends from about 174.1 Ma to about 170.3 Ma (million years ago). It was preceded by the Toarcian and succeeded by the Bajocian. Stratigraphi ...

in age. In the south east of the basin these deposits are known as Purlawaugh Formation which are aged between

Bathonian In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age. ...

. The northern parts are then covered with coal and shale from the Injune Creek Group. In the east they are covered with quartz sand, at the point where run off entered the basin called Blythesdale Group between

Tithonian In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by ...

and

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...

or Pillaga Sandstone which is now known as Pilliga Sandstone. In the Cretaceous sea water entered and deposited shale from the Rolling Downs Group which also contains some calcareous sandstone. Continental sediment also occasionally show in the Cretaceous. Most of the basin is covered by alluvium and lake deposits from the

Cainozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configu ...

period, and this deposition continues till this day. Because the basin is an important site for

artesian well An artesian aquifer is a confined aquifer containing groundwater under positive pressure. An artesian aquifer has trapped water, surrounded by layers of impermeable rock or clay, which apply positive pressure to the water contained within t ...

s, it has been extensively drilled and much is known about the structure of the basement and geothermal temperature gradients. Prominent subsurface features are the Coonamble lobe of the

, round around Moree and

Coonamble Coonamble is a town on the central-western plains of New South Wales, Australia. It lies on the Castlereagh Highway north-west of Gilgandra. At the 2016 census, Coonamble had a population of 2,750. It is the regional hub for wheat growing and ...

. The Culgoa Ridge is underlain by metamorphic rocks, and is near

Brewarrina Brewarrina (pronounced 'bree-warren-ah'; locally known as "Bre") is a town in north-west New South Wales, Australia on the banks of the Barwon River in Brewarrina Shire. The name Brewarrina is derived from 'burru waranha', a Weilwan name for a ...

. The Lila Trough is north of Bourke. The Eulo Shelf is underlain by granite and is southeast of

Hungerford Hungerford is a historic market town and civil parish in Berkshire, England, west of Newbury, east of Marlborough, northeast of Salisbury and 60 miles (97 km) west of London. The Kennet and Avon Canal passes through the town alongside the ...

. The Bulloo Embayment north of White Cliffs is over 300 m deep and is disrupted on its west side by the Warratta Fault. The Quinyamble Trough extends in from South Australia.

Clarence Moreton Basin

The

is in the far north east of the state around Lismore and Grafton, the basin extends into southern Queensland. It formed by oblique extension of the underlying Paleozoic New England Orogen basement. It consists of continental deposits, starting with a small amount of

volcanic rocks and sedimentary sequences including coal beds, and then mostly

and

sedimentary rocks. The basin covers 16000 square kilometers. The basin was named when the Clarence Basin (named after the Clarence River and Moreton Basin in Queensland were proved to be one structure. The first rocks in the Clarence Moreton Basin of New South Wales are the Chillingham Volcanics. These are from some time in the Triassic period, and for a band north and south of Chillingham. They consist of conglomerate at the base, Rhyolite, lithic rhyolitic tuff, and shale. The Nymboida Coal measures extend from Nymboida to Kangaroo Creek. They consist of lithic sandstones (wackes, minor arenites), siltstone, polymictic conglomerate, coal, rhyolitic tuff, and basalt. The total thickness is over 1000 meters. The outcrop is 90 square kilometers, and it forms a north west trending band 29 km long on the southwest tip of the basin. Fossils reveal a date of middle Triassic. A lower part is called Cloughers Creek Formation. The Basin Creek Formation includes the coal mined at Nymboida. The Bardool Conglomerate forming a 180 m thick layer, is also a unit in the coal measures. The conglomerate includes a 15 m thick layer of basalt exposed at Copes Creek. The Red Cliff Coal Measures are from late Triassic. It forms a belt 2.5 km wide and 19 km long from Buchanans Head trough Red Cliff. The Evans Head Coal measure are correlated with these, but are further up the north coast at

Evans Head Evans Head is a town in Richmond Valley Council of the Northern Rivers region of New South Wales, Australia. At the 2016 census, Evans Head had a population of 2,843 people. It is 726 kilometres north of Sydney, and 11 kilometres east off the ...

. The basin was next uplifted and eroded and then deepened considerably and Bundamba group rocks form a complete V shape on both sides of the basin. In the northern parts the rock is mostly friable sandstone, but in the south it is divided into conglomerate below and siltstone above. The Laytons Range Conglomerate rests on the basin floor and extends from Baryulgil, to Nymboida. The conglomerate often appears as a cliff. The Corindi Conglomerate is a local name for a hailstone sized gravel near Corindi. The Mill Creek Siltstone. are often olive green or yellow-brown with bright red joint planes. The Marburg subgroup extends for 225 km along the western side of the basin into Queensland from Corindi. It is mostly clay cemented cross bedded quartz sandstone, but this is interbedded with

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too ...

and shale. At the base is the Blaxland Fossil Wood Conglomerate Member at Blaxlands Creek. The fossil wood is in the form of horizontal tree trunks up to 18 m long and 600 mm diameter. The fossilization process replaced the wood with

limonite Limonite () is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)·H2O, although this is not entirely accurate as the ratio of oxide to hydroxide ...

and

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...

. The Towallum Basalt is a 15-meter thick layer near Nymboida,

Glenreagh Glenreagh is a small town in the Clarence Valley in the Northern Rivers region of north-eastern New South Wales, Australia. At the 2016 census, Glenreagh had a population of 900 people. It is on the North Coast railway line, completed to Gl ...

and Moleton trig station overlying the Marburg formation. The Walloon Coal Measures forms a U shape around the east, south and west sides of the basin. It consists of claystone, shale, siltstone,

arenite Arenite ( Latin: ''arena'', "sand") is a sedimentary clastic rock with sand grain size between 0.0625 mm (0.00246 in) and 2 mm (0.08 in) and contain less than 15% matrix. The related adjective is ''arenaceous''. The equivalen ...

s, and coal seams and the plant fossils in it show a Jurassic age. The next layer of rocks in the basin forming a nested U shape in its exposure is the Kangaroo Creek Sandstone. This sandstone has saccharoidal texture, and glistens white and cream. This is not due to angular sand grains, but results from silica crystallization. It is up to 150 m thick. The Grafton Formation is the sedimentary unit in the geographical centre of the basin. It is the youngest of the beds being between Late Jurassic and early Cretaceous. It occurs from Grafton to

Casino A casino is a facility for certain types of gambling. Casinos are often built near or combined with hotels, resorts, restaurants, retail shopping, cruise ships, and other tourist attractions. Some casinos are also known for hosting live enterta ...

consisting of soft sandstone, siltstone and claystone. Dolerite has intruded this at

Glenugie Peak Glenugie Peak, also known as Mount Elaine or as Glen Ugie Peak, is a mountain that forms part of the ridge surrounding the Clarence Moreton Basin. It is situated in the Northern Rivers region of New South Wales, Australia, and has an elevation o ...

, and near Banyabba. During the Cainozoic, rifting along the east coast of Australia commenced and uplifted the eastern side of the Clarence Moreton Basin. This resulted in the splitting off of the Lord Howe Rise and the opening of the ocean floor.

Murray basin

After Australia separated from Antarctica the Murray basin was formed. The basin floor only subsided slowly over time. The basin became filled with up to 600 m of sediments during the Cenozoic. From

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pala ...

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...

the western side was flooded with sea water and deposited the Warina sand. The sea withdrew and later in the Eocene silt and clay of the Olney Formation were deposited. One minor sea incursion resulted in late Eocene resulted in the Buccleuch Formation in South Australia. This group of deposits is termed the Renmark Group and was earlier known as Knight Group. The sea level rose again in Late

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but t ...

to mid Miocene forming the Murray Group of sediments, with

marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part ...

and

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...

in the deeper locations, and the Geera Clay in the shallow waters. The rock units formed in the deeper water included the Ettric Formation, the Winnanbool Formation and the Mannum Formation limestone with Gambier Limestone in South Australia. When sea level fell again in mid Miocene the deposited Geera clay and Olney Formation moved westward over the limestone. During Upper Miocene to

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Murravian Gulf and resulted in clay and marl in the west called the Bookpurnong Formation, and Calivil Formation river and lake sand in the east. When the sea retreated in

Early Pliocene Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * ...

, the Loxton Sands also informally known as Loxton-Parilla Sands were formed on the beach on the shore of the emergent land. Locally heavy minerals have been concentrated by wave action including

rutile Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer polymorphs of TiO2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest refractive indices at visib ...

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of t ...

and

ilmenite Ilmenite is a titanium-iron oxide mineral with the idealized formula . It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium and the main source of titanium dioxide, which is used in paints, printing ...

forming economic mining opportunities. Lake Bungunnia of the Murray Basin

The

Murray River The Murray River (in South Australia: River Murray) (Ngarrindjeri: ''Millewa'', Yorta Yorta: ''Tongala'') is a river in Southeastern Australia. It is Australia's longest river at extent. Its tributaries include five of the next six longest ...

became dammed by uplift of over 250 meters in the Grampians in Victoria during the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

about 2.5 Mya. The dam formed Lake Bungunnia, which reached 40000 km² and deposited the Blanchetown Clay therein. Higher rainfall of at least 500 mm per year kept the lake filled at first, but during later times rainfall was insufficient and saline lakes formed, depositing dolomite. Even today some saline lakes remain as a remnant of the vast lake. The Murray River carved out a new path to the sea via Murray Bridge replacing its previous exit at

Portland, Victoria Portland is a city in Victoria, Australia, and is the oldest European settlement in the state. It is also the main urban centre in the Shire of Glenelg and is located on Portland Bay. As of the 2021 census the population was 10,016, increasing ...

. The lake was gone by about 0.7 Mya. The Pooraka Formation formed in the north west due to increased erosion resulting in

colluvium Colluvium (also colluvial material or colluvial soil) is a general name for loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rainwash, sheetwash, slow continuous downslope creep, or a variable combinati ...

depositing. The colluvium forms fans, cones and scree slopes, and often contains clay and breccia. In the flat areas the Shepparton Formation also resulted from river deposits of floodplain clay. Most of the existing surface dates from

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million year ...

period. The river deposits from the east have been progressively overlaying the marine deposits further west, as the shore line receded. Within the

deposits are three layers of sand that are aquifers, deposited during higher rainfall periods of the

interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene i ...

s. The floodplain deposits from the current rivers are the Coonambidgal Formation, however this term is used informally for the older Pleistocene flood deposits as well. During the dryer glacial periods the area was arid.

Oaklands basin

The Oaklands Basin covers approximately 3 800 square kilometres in the Riverina district of southern New South Wales, between the towns of Mulwala, Jerilderie, Griffith, Coleambly, Oaklands and Albury. This Permo-Triassic basin trends north-northwest-south-southeast and is concealed beneath the south-eastern portion of the Murray Basin. The basin overlies the Ovens Graben (Ovens Valley Graben in Victoria) which extends from the Murrumbidgee River west of Darlington Point in New South Wales to Wangaratta in Victoria. It is approximately 25 km wide at Oaklands and approximately 15 km wide at its northern extent. The Oaklands Basin hosts to more than 1000 m thick sediments. The basin was first discovered in 1916 when water drillers discovered coal near Coorabin. Coal has been the main focus for exploration within the basin since this time. Extensive coal exploration drilling has been undertaken, mostly in the Coorabin area. In addition two coal drilling programs by the NSW Department of Industry, designed to help define the limits of the basin, have resulted in wide-spaced drilling coverage over most of the basin. Petroleum exploration within the basin has been minimal, consisting of a small number of geophysical surveys and two stratigraphic wells. In 2009 four new lines of high quality 2D seismic have been acquired by DTIRIS (formerly the NSW Department of Industry and Investment). This survey has further delineated the boundaries of the basin, established the thickness of the sediment fill and imaged the structures of the Ovens Valley Graben along the margin and central portion of the basin.

Volcanic rocks

New South Wales has 26,000 km² of volcanic rocks from

period. In the north east major outcrops of volcanic rocks are found between Warialda to Glen Innes and south to

Armidale Armidale is a city in the Northern Tablelands, New South Wales, Australia. Armidale had a population of 24,504 as of June 2018. Estimated resident population, 30 June 2018. It is the administrative centre for the Northern Tablelands region. I ...

, the Liverpool Range,

Barrington Tops Barrington Tops is part of the Great Dividing Range in New South Wales, Australia, between Gloucester and Scone. In 1934, the area was difficult to access and was described as being "not traceable to any man-made feature". Part of the area has ...

Nandewar Range The Nandewar Range, a mountain range that is part of the Great Dividing Range, is located in the North West Slopes region of New South Wales, Australia. The range is situated approximately east of the township of Narrabri. John Oxley was the f ...

near

, the

Warrumbungles The Warrumbungles is a mountain range in the Orana region of New South Wales, Australia. The nearest town is Coonabarabran. The area is easiest accessed from the Newell Highway which is the major road link directly between Melbourne, Victor ...

, and the

Tweed Volcano Tweed Volcano is a partially eroded Early Miocene shield volcano located in northeastern New South Wales, which formed when this region of Australia passed over the East Australia hotspot around 23 million years ago. Mount Warning, Laming ...

Geological history

In the Cambrian and earlier period only the far west of New South Wales existed in its present form. It was joined to what is now Western North America in the

Rodinia Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago and broke up 750–633 million years ago. were prob ...

supercontinent In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leav ...

. North America was detached opening up the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...

. In the

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

period, sediment deposited on the newly formed sea floor, and in the

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleoz ...

a back arc basin behind a chain of volcanoes was formed and then accreted back onto the east coast of Australia to form the Lachlan Fold Belt. The main structure in this is north-south, and this is reflected nowadays with the orientation of rivers and mountain ranges.

Fossils

Collecting fossils is legal in New South Wales under the New South Wales Mining Act with ownership applying to the land owner. Opalised fossils about 100 Mya occur at Lightning Ridge. The Wellington Caves contain megafauna fossils from 4 Mya to 30,000 years old. These include the marsupial lion and giant kangaroo. At Canowindra is the most important fish fossil site in the world. It dates from 360 Mya in the

and includes Groenlandaspis,

Canowindra grossi ''Canowindra'' is a prehistoric lobe-finned fish which lived during the Late Devonian period (about 374 to 359 million years ago). The genus is known from only a single well preserved specimen, dubbed ''Canowindra grossi'', after Professor Walte ...

, Remigolepis walkeri and Bothriolepis yeungae. A museum is there called Age of Fishes Museum. At

Cuddie Springs Cuddie Springs is a notable archaeological and paleontological site in the semi-arid zone of central northern New South Wales, Australia, near Carinda in Walgett Shire. Cuddie Springs is an open site, with the fossil deposits preserved in a c ...

is a fossil site containing

Diprotodon ''Diprotodon'' ( Ancient Greek: "two protruding front teeth") is an extinct genus of marsupial from the Pleistocene of Australia, containing one species, ''D. optatum''. The earliest finds date to 1.77 million to 780,000 years ago, but most s ...

and the Thunder Bird. The Griman Creek Formation contains Cretaceous dinosaur fossils.Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Cretaceous, Australasia)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 573–574. .

Economic geology

Mining

A variety of mines occur in New South Wales, including Broken Hill Ore Deposit the world's richest zinc and silver mine; Bowdens Silver Deposits near

Mudgee Mudgee is a town in the Central West of New South Wales, Australia. It is in the broad fertile Cudgegong River valley north-west of Sydney and is the largest town in the Mid-Western Regional Council local government area as well as being th ...

; Cadia-Ridgeway Mine 20 km south of Orange; Lake Cowal Campaign and Barrick Gold 125 km sw of Parkes; CSA Mine near Cobar mines copper; Endeavour Mine extracts zinc, is 43 km nw of Cobar; Ginko Mineral Sand Deposit is 30 km west of

Pooncarie Pooncarie is a village in south-western New South Wales, Australia in Wentworth Shire. It is on the eastern side of the Darling River between Wentworth and Menindee. The surrounding region of Pooncarie is semi-arid with an outback landscape ri ...

; Murrawombie Mine; Hillgrove Gold Mine 23 km east of

; Mineral Hill 67 km NNW of

Condobolin Condobolin is a town in the west of the Central West region of New South Wales, Australia, on the Lachlan River. At the , Condobolin had a population of 3,486. History Prior to European settlement, the area was inhabited by the Wiradjuri pe ...

; Northparkes is 26 km north of Parkes mining copper; Peak Gold Mine 8 km southeast of

Cobar Cobar is a town in central western New South Wales, Australia whose economy is based mainly upon base metals and gold mining. The town is by road northwest of the state capital, Sydney. It is at the crossroads of the Kidman Way and Barrier H ...

; Peak Hill Gold Mine 50 km north of Parkes; Prungle Mineral Sand Project 50 km north east of Euston; Tritton 18 km north of

Hermidale Hermidale is a village in the Orana region of New South Wales, Australia. It is 600km north-west of Sydney and the two closest towns are Nyngan (46 km to the east) and Cobar (51 km to the west). It lies on the Barrier Highway. At the 2021 Cens ...

; Twelve Mile Mineral Sand Project 40 km east of Pooncarie.

Disasters

The oldest

coal seam fire A coal-seam fire is a burning of an outcrop or underground coal seam. Most coal-seam fires exhibit smouldering combustion, particularly underground coal-seam fires, because of limited atmospheric oxygen availability. Coal-seam fire instances ...

in the world has been burning for 6000 years at

Burning Mountain Burning Mountain, the common name for Mount Wingen, is a hill near Wingen, New South Wales, Australia, approximately north of Sydney just off the New England Highway. It takes its name from a smouldering coal seam running underground through ...

near

Wingen, New South Wales Wingen is a village in the Upper Hunter Shire, in the Hunter Region of New South Wales, Australia. Situated on the New England Highway, it lies about 15 minutes from the town of Scone. It is known for the local ''Burning Mountain Burning ...

. The Newcastle earthquake killed 13 people on 28 December 1989.

History

Study

Government

The Department of Mines commenced in late 1874, and the Geological Survey of New South Wales was brought into existence on 1 January 1875. Charles Smith Wilkinson was its first supervisor. In the 1950s to 1970s the administering body for mines was the New South Wales Department of Mines or New South Wales Department of Mines and Agriculture. Before 2004 New South Wales Department of Mineral Resource After 2004 until July 2009 mining in New South Wales was administered by the

New South Wales Department of Primary Industries The New South Wales Department of Primary Industries (DPI) is an agency of the New South Wales Government, responsible for the administration and development for agriculture, fisheries, aquaculture, forestry, and biosecurity in New South Wales. ...

. and then New South Wales Department of Industry & Investment.

References

External links

* * {{DEFAULTSORT:Geology Of New South Wales