Coordinates | 33°46′22″S151°11′14″E / 33.77274°S 151.18726°E |
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The Hornsby Plateau is a dissected sandstone plateau lying to the north of Sydney Harbour that rises 200 metres. The plateau is a part of the larger Sydney Basin structure. [1]
The North Shore and the Berowra Valley National Park [2] are located on the Hornsby Plateau. It is separated from the Blue Mountains Plateau by the passage of the Colo River. The plateau rises from the Cumberland Plain in the south along a warp line increasing from the proximity of Cattai to Botany Bay. The plateau's elevation ranges between 200-220 metres, with gullies that fall 80-100 metres deep along drainage lines. Steep slopes with drastic ascension of over 100 metres are present. [3] The soil type is generally lithosols, which has low fertility and is normally less than 500 mm deep. [4]
Rock deposits in the Sydney area were tertiary freshwater sediments, which were a rough gravelly layer up to 8 metres thick located beneath silt and sand at a mean depth of 6 metres. As time went by, weathering transformed much of the sandy silt into siliceous clay. At the end of the Tertiary period, or about 80 million years ago, earth movements created an upheaval of 600 metres in most of coastal eastern Australia, due to the rifting and opening of the Tasman Sea. Thus, these movements created the Blue Mountains and Hornsby Plateaux, with the lagging behind of the peneplain becoming the Cumberland Plain. [5]
The plateau was scoured by freshwater streams, which perforated a labyrinth of V-shaped valleys with intruding rocky ridges into the Hawkesbury Sandstone. The drainage activity is ascertained by the Hawkesbury Sandstone's impotence, which were employed by early watercourses. As the creeks carved deeper into the plateau, they began undercutting the sandstone walls of the valley, and as such, blocks of sandstone fell down, thus creating cliff lines. [6]
Due to its hilly topography, the plateau was slow to develop. It has two main sedimentary rock layers: Hawkesbury sandstone, consisting mostly of sandstone, but with some shale, and the overlying Ashfield Shale, which supports richer vegetation. There are also a few volcanic intrusions throughout the plateau.
Ku-ring-gai Chase National Park is a national park on the northern side of Sydney in New South Wales, Australia. The 14,977-hectare (37,010-acre) park is 25 kilometres (16 mi) north of the Sydney central business district and generally comprises the land east of the M1 Pacific Motorway, south of the Hawkesbury River, west of Pittwater and north of Mona Vale Road. It includes Barrenjoey Headland on the eastern side of Pittwater.
The Wollemi National Park is a protected national park and wilderness area that is located in the Central West and Hunter region of New South Wales, in eastern Australia. The 501,703-hectare (1,239,740-acre) park, the second largest national park in New South Wales, contains the 361,113-hectare (892,330-acre) Wollemi Wilderness – the largest such wilderness area in Australia – and is situated approximately 130 kilometres (81 mi) northwest of Sydney.
The exposed geology of the Bryce Canyon area in Utah shows a record of deposition that covers the last part of the Cretaceous Period and the first half of the Cenozoic era in that part of North America. The ancient depositional environment of the region around what is now Bryce Canyon National Park varied from the warm shallow sea in which the Dakota Sandstone and the Tropic Shale were deposited to the cool streams and lakes that contributed sediment to the colorful Claron Formation that dominates the park's amphitheaters.
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. The basin is named for the city of Sydney, on which it is centred.
Bents Basin is a protected nature reserve and state park near Wallacia, New South Wales, Australia in the Sydney metropolitan area. The lake basin, which formed at the efflux of the Nepean River from the Hawkesbury Sandstone gorge, is a popular swimming hole with a camping area and an education centre used by local school groups. Also featuring a large woodland area and native wildlife, the reserve is the only picnic area along the Nepean River and it is one of the most popular water-based picnic parks in Greater Western Sydney.
Long Island is an elongated island of 73 hectares in the Hawkesbury River, about 50 kilometres (31 mi) north of the Sydney central business district,New South Wales, Australia. It is joined to the mainland at its south eastern edge by the railway causeway across Sandbrook Inlet. At the other end of this causeway is the Sydney suburb of Brooklyn in Hornsby Shire, to which Long Island belongs.
The Berowra Creek, a watercourse that is part of the Hawkesbury-Nepean catchment, is located to the north of the Sydney central business district in the Hornsby Shire of New South Wales, Australia.
The geology of Tennessee is as diverse as its landscapes. Politically, Tennessee is broken up into three Grand Divisions: East, Middle, and West Tennessee. Physically, Tennessee is also separated into three main types of landforms: river valley plain, highlands and basins, and mountains.
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.
The Cumberland Plain, also known as Cumberland Basin, is a relatively flat region lying to the west of Sydney CBD in New South Wales, Australia. An IBRA biogeographic region, Cumberland Basin is the preferred physiographic and geological term for the low-lying plain of the Permian-Triassic Sydney Basin found between Sydney and the Blue Mountains, and it is a structural sub-basin of the Sydney Basin.
The Sydney Turpentine-Ironbark Forest (STIF) is a wet sclerophyll forest community of Sydney, New South Wales, Australia, that is typically found in the Inner West and Northern region of Sydney. It is also among the three of these plant communities which have been classified as Endangered, under the New South Wales government's Threatened Species Conservation Act 1995, with only around 0.5% of its original pre-settlement range remaining.
The Wianamatta Group is a geological feature of the Sydney Basin, New South Wales, Australia that directly overlies the older Hawkesbury sandstone and generally comprise fine grained sedimentary rocks such as shales and laminites as well as less common sandstone units.
Cumberland State Forest is a wet sclerophyll forest in Sydney, New South Wales, Australia. Situated on the southern edge of the Hornsby Plateau, the forest is located in the suburb of West Pennant Hills, Sydney and contains 40 hectares of native forest. It is the only metropolitan state forest in Australia and it is considered unique in comparison to the other state forests of NSW. The forest receives about 150,000 visitors annually.
Ashfield Shale is part of the Wianamatta group of sedimentary rocks in the Sydney Basin. It lies directly on contemporaneously eroded Hawkesbury sandstone or the Mittagong formation. These rock types were formed in the Triassic Period. It is named after the Sydney suburb of Ashfield. Some of the early research was performed at the old Ashfield Brickworks Quarry. This rock type is often associated with the Inner West and North Shore of the city. However, it has also been recorded at Penrith, Revesby, Bilpin and Mount Irvine.
The Berowra Valley National Park is a protected national park that is located in northern Sydney, New South Wales, Australia. The 3,884-hectare (9,600-acre) national park is situated approximately 20 kilometres (12 mi) north-west of the Sydney central business district.
The Cumberland Plain Woodland, also known as Cumberland Plain Bushland and Western Sydney woodland, is a grassy woodland community found predominantly in Western Sydney, New South Wales, Australia, that comprises an open tree canopy, a groundcover with grasses and herbs, usually with layers of shrubs and/or small trees.
The Sydney Sandstone Ridgetop Woodland, also known as Coastal Sandstone Ridgetop Woodland and Hornsby Enriched Sandstone Exposed Woodland, is a shrubby woodland and mallee community situated in northern parts of Sydney, Australia, where it is found predominantly on ridgetops and slopes of the Hornsby Plateau, Woronora Plateau and the lower Blue Mountains area. It is an area of high biodiversity, existing on poor sandstone soils, with regular wildfires, and moderate rainfall.
The ecology of Sydney, located in the state of New South Wales, Australia, is diverse for its size, where it would mainly feature biomes such as grassy woodlands or savannas and some sclerophyll forests, with some pockets of mallee shrublands, riparian forests, heathlands, and wetlands, in addition to small temperate and subtropical rainforest fragments.
The Shale Sandstone Transition Forest, also known as Cumberland Shale-Sandstone Ironbark Forest, is a transitory ecotone between the grassy woodlands of the Cumberland Plain Woodlands and the dry sclerophyll forests of the sandstone plateaus on the edges of the Cumberland Plain in Sydney, Australia.
The Coastal Upland Swamps are critically endangered swamp areas scattered in the Sydney area and the Illawarra Escarpment which feature flora and fauna associated with sporadically marshy soils on the Hawkesbury sandstone plateaus. It occurs in the eastern Sydney area from the Somersby district in the north to Robertson in the south.