Thegeography of Sydney is characterised by its coastal location on a basin bordered by thePacific Ocean to the east, theBlue Mountains to the west, theHawkesbury River to the north and theWoronora Plateau to the south.Sydney lies on asubmergent coastline on the east coast ofNew South Wales, where the ocean level has risen to flood deep river valleys (rias) carved in theSydney sandstone.^[1]Port Jackson, better known as Sydney Harbour, is one such ria.^[2]

The Sydney area lies onTriassicshales andsandstones. The region mostly consists of low rolling hills and wide valleys in arain shadow area that is shielded by theGreat Dividing Range.^[3] Sydney sprawls over two major regions: theCumberland Plain, a relatively flat region lying to the west of Sydney Harbour, and theHornsby Plateau, aplateau north of the Harbour rising to 200 metres and dissected by steep valleys.^[4] Sydney's native plant species are predominantlyeucalyptus trees,^[5] and itssoils are usually red and yellow in texture. The endemic flora is home to a variety ofbird,insect,reptile andmammal species, which are conspicuous in urban areas.^[6]

There are more than 70 harbour and ocean beaches in the urban area. Most of Sydney's water storages are on tributaries of theNepean River.Parramatta River drains a large area of Sydney's western suburbs.^[7] With 5,005,400 inhabitants (as of 2016) and an urban population density of 2037 people per square kilometre, Sydney'surban area covers 1,788 km² (690 sq mi),^[8] comprising 35% of Sydney and is constantly growing.^[9]

Greater Sydney's boundaries stretch 80 kilometres (50 mi) fromPalm Beach in the north to theRoyal National Park in the south, and 80 kilometres (50 mi) fromBondi Beach in the east to theBlue Mountains in the west.

The rising sea level between 18,000 and 6,000 years ago flooded the rias to form estuaries and deep harbours.Erosion by coastal streams has created a landscape of deepcanyons and remnantplateaus.^[10] The city hasfault lines which run considerably deep beneath theSydney basin, dating back to whenNew Zealand started breaking away from Australia more than 85 million years ago.^[11][12] To the east the basin continues to the edge of thecontinental shelf.^[13] TheAustralian continental shelf is about 25.9 km (16.1 mi) away fromSydney Heads, which is the location of theTasman Abyssal Plain.^[14][15] The centre of the basin is located around 30 kilometres (19 mi) west of theSydney central business district atFairfield.^[16][17]

The sand that was to become the sandstone of today was washed fromBroken Hill and laid down about 200 million years ago. The ripple marks from the ancient river that brought the grains of sand are distinctive and easily seen, telling geologists that the sand comes from rocks formed between 500 and 700 million years ago far to the south. This means that the highest part of the visible lines almost always faces approximately south.^[18] There are volcanic rocks from low hills in the shale landscapes. The Basin'ssedimentary rocks have been subject to uplift with gentle folding and minor faulting during the formation of theGreat Dividing Range.^[19]

At a time in the past,monocline formed to the west of Sydney. The monocline is a sloping bend that raises the sandstone well above where it is expected to be seen, and this is why the whole of the visible top of the Blue Mountains is made of sandstone. Sandstone slopes in the Sydney area are on three sides: to the west the Blue Mountains, and to the north and south, the Hornsby and Woronora plateaux'.^[20][21][22]

Being veryporous, the Sydney sandstone hasshale lenses and fossil riverbeds dotted throughout and it is some 200 metres (656 feet) thick. The sandstone was probably deposited in a freshwater delta and is thecaprock which controls the erosion andscarp retreat of theIllawarra escarpment.^[23] Six kilometres of sandstone and shale lie under Sydney.^[24]Bringelly Shale andMinchinbury Sandstone are often seen in the greater western parts of Sydney.^[25][26]Ashfield Shale is observed in the inner western suburbs.^[27] These components are part of theWianamatta Shale group.^[23]Mittagong Formation sighted in a few areas in northern Sydney.^[28]

TheProspect dolerite intrusion inwestern Sydney is the largest assemblage ofigneous rock in Sydney. The oval-shaped ridge was made many millions of years ago whenvolcanic material from the Earth'supper mantle moved upwards and then sideways.^[29] Slow erosion of the overlying layers of sedimentary rock by the flow ofrainwater have eventually laid bare the edges of thevolcanic andmetamorphic rocks of theintrusion.^[30]The Gap, an oceancliff on theSouth Head peninsula inWatsons Bay,^[31] was laid assediment more than 200 million years ago in the Triassic period. During theJurassic period, a cataclysmic event resulted in an enormous crack forming within the strata. The Gap itself forms a sequence that continues offshore to the edge of theSahul Shelf.^[32]

Sydney features two major soils;sandy soils (such as red, brown and yellowpodsols, grey and browntenosols,lithosols, kandosols and kurosols)^[33] which originate from the Hawkesbury sandstone and have lowfertility, andclay soils (which are from shales andvolcanic rocks), though some soils may be a mixture of the aforementioned soils (such as sandy clayloams andsilty clay loam).^{[34][35][36][37]}

Sydney has a number ofislands in its harbour and surrounding rivers. Such islands include,Shark Island,Cockatoo Island,Clark Island,Snapper Island,Spectacle Island andGoat Island in Port Jackson.Bare Island inBotany Bay.Lion Island,Long Island andMilson Island inHawkesbury River.Scotland Island in the Northern Beaches. AndRodd Island inParramatta River.^[38]

Overall, Sydney has nine rivers and just over a hundredcreeks. The Nepean River rises to the south in the Woronora Plateau, and wraps around the western edge of the city.Swamps andlagoons are existent on the floodplain of theNepean River, one beingBents Basin, which is also a recreational area. Where the Nepean turns east it becomes theHawkesbury River, which winds through the Hornsby Plateau before emptying intoBroken Bay. Broken Bay and the lower Hawkesbury form the commonly accepted boundary between Sydney and theCentral Coast to the north. The remaining section ofWarragamba River flows 3.5 kilometres (2.2 mi) north-east from theWarragamba Dam spillway to its confluence with the Nepean River.^[39]

The south and southwest of Sydney is drained by theGeorges River, flowing north from its source near Appin, towardsLiverpool and then turning east towardsBotany Bay. The other major tributary of Botany Bay is theCooks River, running through the inner-south western suburbs of Canterbury and Tempe. The Georges River estuary separates the main part of Sydney's urban area from theSutherland Shire. TheWoronora River, on the southern edge of the Sydney Plain, flows in a steep-sided valley from theWoronora Dam to the eastern estuary of the Georges River. TheHacking River is further south and runs through The Royal National Park intoPort Hacking which forms the southern boundary of theSutherland Shire.

Parramatta River's headwaters are several local creeks includingToongabbie Creek andHunts Creek, part of the upper Parramatta river catchment area.Duck River is the river's southern tributary. Hunt's creek flows fromLake Parramatta, a few kilometres North ofParramatta. At east Parramatta the river becomes a tidal estuary that flows intoPort Jackson, commonly known as Sydney harbour. Other major tributaries flow into Port Jackson from the North Shore and are theLane Cove River andMiddle Harbour Creek.

Minor waterways draining Sydney's western suburbs includeSouth Creek andEastern Creek, flowing into the Hawkesbury, andProspect Creek draining into the Georges River.Cowan Creek andBerowra Creek run north from theUpper North Shore to the Hawkesbury river.^[40] The creeks draining into Georges River were described as "a chain of ponds" by the early European settlers, because these creeks were more like a series ofponds rather than an unbroken stream, before the disturbance of their banks by the settlers.^[41]

The predominantplant communities in the Sydney region are grassy woodlands, which are open woodlands scattered with sclerophyllousshrubs and sparse grass in theunderstory.^[43] Wet and dry sclerophyll forest exist in some pockets, withheathlands andtemperate/subtropical rainforests occurring in a few areas as well, thus making the Sydney region have distinctbiomes. Dry sclerophyll forests, reminiscent ofMediterranean forests, are the most widespread forest type in the region, which occur sporadically in theCumberland Plain and would feature dry,eucalyptus woodland.^[44] On the other hand, wet sclerophyll forests, which fall undertemperate forests, have narrow, relatively tall, dense trees with a lush, moistunderstorey of fleecy shrubs andtree ferns. They are found in the cooler, wetter areas such asNorthern Suburbs,Forest District,North Shore and in theBlue Mountains.^[45]

Sclerophyll forests developed as a result of the extreme age of thecontinent combined with Aboriginal fire use. Deepweathering of the crust leached chemicals out of the rock, leaving Australian soils deficient in nutrients. The sandstone is the basis of thenutrient-poor soils found in Sydney that developed over millennia and 'came to nurture a brilliant and immensely diverse array ofplants'. As plants cannot afford to lose leaves toherbivores when nutrients are scarce, they defend theirfoliage with toxins. In eucalypts, these toxins give the bush its distinctive smell.^[46] It has been calculated that around 98,000 hectares of native vegetation remains in the Sydney metropolitan area, about half of what is likely to have been existing at the time of European arrival.^[47]

According to theSenseable City Lab at theMassachusetts Institute of Technology (MIT), which measures canopy cover in the world's most prominent cities, the Sydney area had a Green View Index of 25.9% – This represents the total percentage of the city covered byurban trees. Tying withVancouver at that percentage, Sydney is the third prominent city in the world with the most trees afterSingapore andOslo, respectively.^[49] Because the Sydney metropolitan area is encircled by a large area of bushland and forest to the north, west and south of its peripheries,^[50]bushfires can ring the region during intense bushfire seasons; thisnatural phenomenon that surrounds Sydney has been labelled "ring of fire".^{[51][52][53][54]}

The fauna of the Sydney area is diverse and its urban area is home to variety of bird and insect species, and also a fewbat,arachnid andamphibian species. Sydney is home to dozens ofbird species, which mainly include theAustralian white ibis,Australian raven,Australian magpie,crested pigeon,grey butcherbird,magpie lark,noisy miner,pied currawong,silver gull andwillie wagtail, among others.Introduced birds such as thehouse sparrow,common myna andferal pigeon are ubiquitous in the CBD areas of Sydney.^[55][56]

Moreover,possums,bandicoots,rabbits,feral cats,lizards,snakes andfrogs may also be present in the urban environment, albeit seldom incity centers.^[57]

The extensive area covered by urban Sydney is formally divided into more than 650 suburbs for addressing and postal purposes, and administered as 38 local government areas. TheCity of Sydney itself covers a fairly small area comprising the central business district and its neighbouring inner-city suburbs. The151st meridian east passes through the western suburbs ofGranville andRevesby, among others. The suburbs to the west of those lie on the eastern end of the150th meridian, which is a line that passes through theRussian city ofMagadan in theNorthern Hemisphere.^[58]

TheSydney central business district (CBD) extends southwards for about 2 km (1.2 mi) fromSydney Cove, the point of the first European settlement. The west side is bounded byDarling Harbour, a popular tourist and nightlife precinct whileCentral station marks the southern end of the CBD.George Street serves as the Sydney CBD's main north–south thoroughfare.^[59] The oldest parts of the city are located in the flat areas south of the harbour; theNorth Shore was slower to develop because of its hilly topography, and was mostly a quietbackwater until theSydney Harbour Bridge was opened in 1932, linking it to the rest of the city, with the suburbs surrounding the northern entrance to said bridge effectively developingNorth Sydney into a secondcentral business district.^[60]

TheEastern Suburbs sit on the coast of Sydney. They contain iconic beaches such asBondi Beach andCoogee Beach, and feature prominent seaside cliffs. The suburbs ofMaroubra,Coogee andBondi Junction lie on steep slopes, and would have an elevation of 90 metres (295 feet) at the highest peaks. These suburbs are located in generally close proximity to the city centre and are serviced by rail networks. The landscape in these areas is characterized by winding crescent-like streets with harbourside beaches and villages.

TheNorthern Suburbs of Sydney are characterised by pristinewaterways with immense greenery and large plots of manicured land. Being around 80 to 180 metres (260 to 590 ft) abovesea level, the region is very hilly and has a higher elevation than the rest of Sydney. Most of theNorth Shore suburbs are part of the Hawkesbury Plateau, a large sandstone plateau overlaid by a system of hilly ridges andgullies. Major waterways in the region include theParramatta River,Lane Cove River and the many creek systems that branch out from these. The region is home to many parks andnature reserves – TheLane Cove National Park and theGarigal National Park include many areas of remnant bushland adjacent to theLane Cove River andMiddle Harbour.

TheHills District, situated halfway between the northern suburbs and greater western Sydney, is a region so named for its characteristically comparatively hilly topography, akin to the Northern Suburbs and North Shore. Several of its suburbs have the word 'Hills' in their names. As the name indicates, the Hills District, depending on the suburb, is around 80 to 180 metres (260 to 590 ft) above sea level. As such, its elevation createsorographic rainfall brought in by onshore winds from the Pacific Ocean.^[61]

Thewestern suburbs predominantly lie on theCumberland Plain and are relatively flat in contrast to the above regions.^[62] They are situated on a rain shadow, thanks to the Hills District to the northeast. Thus, they tend to be drier than the coast and less lush than the hilly Northern Suburbs.^[63] Despite being known as "flat", there are a number of ridgy areas on the plain –Western Sydney Regional Park andProspect Hill are between 130 and 140 metres (430 and 460 ft) high. Highly elevated suburbs, which typically range between 70 and 100 metres (230 and 330 ft) in height, includeLeppington andOran Park to the southwest,Pemulwuy,Cecil Hills andHorsley Park to the greater west, andGreystanes,Seven Hills andMount Druitt to the northwest.^[64]Agriculture is mainly concentrated in the outskirts of theGreater Western Sydney area, such as in suburbs ofKemps Creek,Orchard Hills,Luddenham andHorsley Park, among others, which lie in acountryside.^[65]

TheBlue Mountains (sometimes considered part of Greater Sydney) rise to the west of the western suburbs up to a height of 1,189 metres (3,901 ft), the highest point in the Sydney region.

The Sydney CBD contains prominentparks such as,Hyde Park,The Domain andRoyal Botanic Gardens andFarm Cove on the harbour. Other parks in that vicinity includeWynyard andHyde Park. The Royal Botanic Gardens is the most important green space in the Sydney region, hosting both scientific and leisure activities.^[66] There are 15 separate parks under the administration of the City of Sydney.^[67] The Royal National Park was proclaimed on 26 April 1879 and with 13,200 hectares (51 square miles) is the second oldestnational park in the world.^[68]

The largest park in the Sydney metropolitan region is Ku-ring-gai Chase National Park, established in 1894 with an area of 15,400 hectares (59 square miles).^[69] It is regarded for its well-preserved records of indigenous habitation and more than 800 rock engravings,cave drawings, and middens have been located in the park.^[70] The Domain is the oldest public parkland in Australia and measures 16.2 hectares (0.1 square miles) in area.^[71] Its location was used for both relaxation and the grazing of animals from the earliest days of the colony.^[72]

The inner west suburbs includeCentennial Park andMoore Park in the east,Sydney Park andRoyal National Park in the south,Ku-ring-gai Chase National Park in the north, andWestern Sydney Parklands in the west. Other major parks in the Sydney metropolitan area includeAuburn Botanical Gardens,Central Gardens Nature Reserve,Heathcote National Park,Georges River National Park,Lane Cove National Park andBlue Mountains National Park. There are large parks and reserves surrounding prominent bodies of water, such as those aroundProspect Reservoir,Chipping Norton Lake,Lake Parramatta andNepean River (Bents Basin).^[73]

Sydney has some of the finest and most famous beaches in the world. There are well over 100 beaches in the city, ranging in size from a few metres to several kilometres, located along the city'sPacific Ocean coastline and its harbours, bays and rivers. With around 70 surf beaches and dozens of harbour coves, Sydney is almost unrivalled in the world for the number and quality of beaches available.^[74] The water and sand among the city beaches, despite their popularity, are remarkably clean.^[75] The beach watch program was established in 1989 in response to community concern about the impact of sewage pollution on human health and the environment at Sydney's ocean beaches.^[76]

There are a number of informal regional names describing large sections of the urban area. Not all suburbs are necessarily covered by any of the following informal regional categories.^[77]

The regions areCanterbury-Bankstown, theEastern Suburbs, theForest District,Greater Western Sydney, theHills District, theInner West, theMacarthur region, theNorthern Beaches, theNorthern Suburbs, theNorth Shore,Southern Sydney,South Western Sydney, theSt George district, theSutherland Shire andWestern Sydney. The Blue Mountains are at times considered to be part of Sydney's metropolitan area.

The largest commercial centres outside of the CBD areNorth Sydney andChatswood in the north,Parramatta to the west,Liverpool in the south-west,Hurstville in the south andBondi Junction to the east. There has been accelerating commercial development in Parramatta since the 1950s as firms serving Western Sydney have set up regional offices and recognised the region's significant residential population mass and cheaper rents.^[78]

Sydney has ahumid subtropical climate (Cfa) with warm and sometimes hot summers, and winters shifting from mild to cool. Although Sydney is predominantly humid subtropical, the hilly areas of theForest District, such asTerrey Hills, among others, have a borderlineoceanic climate (Cfb). The weather is moderated by proximity to the ocean, and more extreme temperatures are recorded in the inland western suburbs.^[79]

The warmest month in the CBD is January, with an average air temperature range atObservatory Hill of 19.6–26.5 °C (67.3–79.7 °F). The coldest month is July, with an average range of 8.7–17.4 °C (47.7–63.3 °F). In the west, the temperatures average between 17.5 and 28.4 °C (63.5 and 83.1 °F) in summer. In winter, they're normally between 6.2 and 17.4 °C (43.2 and 63.3 °F). In late spring and summer, Sydney can sometimes get northwesterly winds from theOutback, which are dry and hot, making the temperatures reach above 40 °C (104.0 °F).Frost is oftentimes observed in the outer suburbs.^[80]

Rainfall is spread throughout the year, but is slightly higher during the first half of the year when easterly winds dominate.^[81] Sydney's coast generally receives around 1,000 mm (39.37 in) to 1,200 mm (47.24 in) of rain annually. The western suburbs receive around 800 mm (31.50 in) to 900 mm (35.43 in) of precipitation, since moist onshore winds do not penetrate inland.Australian east coast low brings large amounts of rain in late autumn and winter.^[82]

• Sydney basin
• Geology of New South Wales
• Geology of Australia
• Cumberland Plain Woodland
• Sydney sandstone
• Bald Hill Claystone
• Geography of Australia
• Geography of New South Wales
• List of beaches in Sydney
• Cities portal

• Australian Heritage Commission (1981).The Heritage of Australia : the illustrated register of the National Estate. South Melbourne The Macmillan Company of Australia in association with the Australian Heritage Commission.ISBN 978-0-333-33750-9.
• Branagan, David F.; Packham, Gordon H. (2000).Field geology of New South Wales. Sydney: New South Wales Department of Mineral Resources.ISBN 0-7313-9222-1.
• Fairley, A; Moore, P (2000).Native Plants of the Sydney District: An Identification Guide (2nd ed.). East Roseville: Kangaroo Press.ISBN 0-7318-1031-7.
• Flannery, Tim, ed. (1999).The Birth of Sydney. Melbourne:Text Publishing.ISBN 1-876485-45-0.
• Forster, Clive A (1995).Australian cities : continuity and change.Oxford University Press.ISBN 978-0-19-553565-5.
• Herbert, Chris; Helby, Robin, eds. (1980).A Guide to the Sydney Basin. D. West, Govt. Printer.ISBN 978-0-7240-1250-3.
• Karskens, Grace (2010).The Colony, A History of Early Sydney. Sydney:Allen & Unwin.ISBN 978-1-74237-364-5.
• Packham, Gordon H, ed. (1969).The geology of New South Wales.Geological Society of Australia.

• Map of Sydney suburbs from Dictionary of SydneyArchived 9 April 2008 at theWayback Machine
• Regional Plan for SydneyArchived 25 March 2018 at theWayback Machine
• Geology of the Sydney Basin
• Triassic Rocks of Sydney
• Sydney Metropolitan Vegetation
• Urban Forest StrategyArchived 4 April 2015 at theWayback Machine
• Wildlife of Sydney
• Birds of Sydney

• Geography of Sydney
• Geology of New South Wales
• Biogeography of New South Wales
• Environment of Australia
• Sydney

• Webarchive template wayback links
• CS1 maint: multiple names: authors list
• Geographic Names Register of NSW not in Wikidata
• Articles with short description
• Short description is different from Wikidata
• Use dmy dates from August 2022
• Use Australian English from April 2013
• All Wikipedia articles written in Australian English