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. Sydney lies on a submergent coastline on the east coast of New South Wales, where the ocean level has risen to flood deep river valleys (rias) carved in the Sydney sandstone. Port Jackson, better known as Sydney Harbour, is one such ria.^[1]

The Sydney area lies on Triassic shales and sandstones. The region mostly consists of low rolling hills and wide valleys in a rain shadow area that is shielded by the Great Dividing Range.^[2] Sydney sprawls over two major regions: the Cumberland Plain, a relatively flat region lying to the west of Sydney Harbour, and the Hornsby Plateau, a plateau north of the Harbour rising to 200 metres and dissected by steep valleys.^[3] Sydney's native plant species are predominantly eucalyptus trees,^[4] and its soils are usually red and yellow in texture. The endemic flora is home to a variety of bird, insect, reptile and mammal species, which are conspicuous in urban areas.^[5]

There are more than 70 harbour and ocean beaches in the urban area. Most of Sydney's water storages are on tributaries of the Nepean River. Parramatta River drains a large area of Sydney's western suburbs.^[6] With 5,005,400 inhabitants (as of 2016) and an urban population density of 2037 people per square kilometre, Sydney's urban area covers 1,788 km² (690 sq mi),^[7] comprising 35% of Sydney and is constantly growing.^[8]

Greater Sydney's boundaries stretch 80 kilometres (50 mi) from Palm Beach in the north to the Royal National Park in the south, and 80 kilometres (50 mi) from Bondi Beach in the east to the Blue Mountains in the west.