 The river valleys of the plateau | |
  | |
| Coordinates | 33°46′22″S151°11′14″E / 33.77274°S 151.18726°E |
|---|---|
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 northern Blue Mountains and Lower Hunter regions 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.
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, an IBRA biogeographic region, is a relatively flat region lying to the west of Sydney CBD in New South Wales, Australia. 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 glacial history of Minnesota is most defined since the onset of the last glacial period, which ended some 10,000 years ago. Within the last million years, most of the Midwestern United States and much of Canada were covered at one time or another with an ice sheet. This continental glacier had a profound effect on the surface features of the area over which it moved. Vast quantities of rock and soil were scraped from the glacial centers to its margins by slowly moving ice and redeposited as drift or till. Much of this drift was dumped into old preglacial river valleys, while some of it was heaped into belts of hills at the margin of the glacier. The chief result of glaciation has been the modification of the preglacial topography by the deposition of drift over the countryside. However, continental glaciers possess great power of erosion and may actually modify the preglacial land surface by scouring and abrading rather than by the deposition of the drift.
The Sydney Turpentine-Ironbark Forest (STIF) is one of six main indigenous forest communities of Sydney, New South Wales, Australia, that is typically in the Inner West 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. As of 26 August 2005, the Australian Government reclassified Sydney Turpentine-Ironbark Forest as a "Critically Endangered Ecological Community", under the Commonwealth's Environment Protection and Biodiversity Conservation Act 1999.
The Wianamatta Group is a geological feature of the Sydney Basin, New South Wales, Australia. The Wianamatta Group directly overlies the older Hawkesbury sandstone. The shales generally comprises fine grained sedimentary rocks such as shales and laminites with less common sandstone units.
The U.S. state of Tennessee is geographically diverse, with varying terrains and several distinct physiographic regions. Its landforms range from the Blue Ridge Mountains in the eastern part of the state to flat and fertile plains along the Mississippi River. The state is geographically, legally, culturally, and economically divided into three Grand Divisions: East Tennessee, Middle Tennessee, and West Tennessee.
The Berowra Waters Ferry is a cable ferry across the Berowra Creek, a tributary of the Hawkesbury River, located in the Berowra Valley National Park in northern Sydney, New South Wales, Australia. The ferry operates from the community of Berowra Waters on the west bank of the creek, to a landing on the east bank, thus connecting with the road to Berowra Heights.
Ashfield Shale is part of the Wiannamatta 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.
Bringelly Shale is a component of the Wianamatta group of sedimentary rocks in the Sydney Basin of eastern Australia. Formed in the Triassic Period, it has an extensive outcrop in the western parts of Sydney. The shale has its greatest geographical extent at Bringelly, near the suburb of Liverpool.
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. Located within the Sydney Basin, the park is part of the dissected Hornsby Plateau which is dominated by Hawkesbury Sandstone and predominately covers the catchment area of Berowra Creek.
The Cumberland Plain Woodland is one of six main indigenous woodland communities of 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. Situated in the Cumberland Plain, it is made up of dry sclerophyll woodlands, grasslands and/or forests, reminiscent of Mediterranean forests and temperate grasslands.
The Sydney Sandstone Ridgetop Woodland is one of six main indigenous forest communities of Sydney, Australia 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 and some sclerophyll forests, with a few pockets of mallee shrublands, subtropical and temperate rainforests (evergreen), heathlands, and wetlands. The combination of climate, topography, moisture, and soil influence the dispersion of these ecological communities across a height gradient from 0 to 200 metres. There are many hiking trails, paved and unpaved roads for exploring the many different biomes and ecosystems.
Coordinates: 33°42′18″S151°05′56″E / 33.70490°S 151.09901°E