Geography of Sydney
The geography of Sydney is characterised by its coastal location on a basin bordered by the Pacific Ocean to the east, the Blue Mountains to the west, the Hawkesbury River to the north and the Woronora Plateau to the south.
The region mostly consists of low rolling hills and wide valleys in a rain shadow area that is shielded by the Great Dividing Range.
[10] The city has fault lines which run considerably deep beneath the Sydney basin, dating back to when New Zealand started breaking away from Australia more than 85 million years ago.
The Basin's sedimentary rocks have been subject to uplift with gentle folding and minor faulting during the formation of the Great Dividing Range.
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'.
The oval-shaped ridge was made many millions of years ago when volcanic material from the Earth's upper mantle moved upwards and then sideways.
[30] The Gap, an ocean cliff on the South Head peninsula in Watsons Bay,[31] was laid as sediment more than 200 million years ago in the Triassic period.
Broken Bay and the lower Hawkesbury form the commonly accepted boundary between Sydney and the Central Coast to the north.
[39] The south and southwest of Sydney is drained by the Georges River, flowing north from its source near Appin, towards Liverpool and then turning east towards Botany Bay.
The other major tributary of Botany Bay is the Cooks River, running through the inner-south western suburbs of Canterbury and Tempe.
Other major tributaries flow into Port Jackson from the North Shore and are the Lane Cove River and Middle Harbour Creek.
[42] Wet and dry sclerophyll forest exist in some pockets, with heathlands and temperate/subtropical rainforests occurring in a few areas as well, thus making the Sydney region have distinct biomes.
They are found in the cooler, wetter areas such as Northern Suburbs, Forest District, North Shore and in the Blue Mountains.
The sandstone is the basis of the nutrient-poor soils found in Sydney that developed over millennia and 'came to nurture a brilliant and immensely diverse array of plants'.
[45] 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.
Introduced birds such as the house sparrow, common myna and feral pigeon are ubiquitous in the CBD areas of Sydney.
[54][55] Moreover, possums, bandicoots, rabbits, feral cats, lizards, snakes and frogs may also be present in the urban environment, albeit seldom in city centers.
The City of Sydney itself covers a fairly small area comprising the central business district and its neighbouring inner-city suburbs.
The suburbs to the west of those lie on the eastern end of the 150th meridian, which is a line that passes through the Russian city of Magadan in the Northern Hemisphere.
The west side is bounded by Darling Harbour, a popular tourist and nightlife precinct while Central station marks the southern end of the CBD.
[58] The oldest parts of the city are located in the flat areas south of the harbour; the North Shore was slower to develop because of its hilly topography, and was mostly a quiet backwater until the Sydney 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 developing North Sydney into a second central business district.
The suburbs of Maroubra, Coogee and Bondi Junction lie on steep slopes, and would have an elevation of 90 metres (295 feet) at the highest peaks.
The Northern Suburbs of Sydney are characterised by pristine waterways with immense greenery and large plots of manicured land.
[62] Despite being known as "flat", there are a number of ridgy areas on the plain – Western Sydney Regional Park and Prospect Hill are between 130 and 140 metres (430 and 460 ft) high.
[63] Agriculture is mainly concentrated in the outskirts of the Greater Western Sydney area, such as in suburbs of Kemps Creek, Orchard Hills, Luddenham and Horsley Park, among others, which lie in a countryside.
The Royal Botanic Gardens is the most important green space in the Sydney region, hosting both scientific and leisure activities.
[77] Sydney has a humid 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 the Forest District, such as Terrey Hills, among others, have a borderline oceanic climate (Cfb).
In late spring and summer, Sydney can sometimes get northwesterly winds from the Outback, which are dry and hot, making the temperatures reach above 40 °C (104.0 °F).
