Terrain shapes and bedrock
Low relief and extreme drought leave their mark on most of Australia’s land surface. Less than 6% of the area is above 700 m level, and larger altitude areas are missing, with the exception of a mountain range along the east coast. Low plains and vast plateau surfaces dominate. The geographical location has led to a quiet development, where erosion and leveling of the land surface has been able to continue for a very long time. Three topographic areas can be distinguished: the plateau area to the west, the basin area to the center and the highlands to the east.
Most of the western plateau area rests on a mountain shield, once part of the Gondwana continent, which greatly affected landform formation. Through long and straight crack lines, lineament, the plateau area has been divided into several separate blocks. Some of these have been elevated and comprise altitude areas, such as the Kimberley Plateau, Arnhem Land, the Hamersley Mountains (1,227 m above sea level) and Isah Highlands, as well as in the middle of the Macdonell Mountains (1,550 m above sea level) and the Musgrave Mountains (1,440 m above sea level)..). In these elevation areas, the bedrock consists of oblique layers, which, through their different hardness, have given rise to a back and valley topography. Other blocks have been lowered and become lowland or basin areas, such as the Barkley Plateau, Canningbäckenet with the Great Sand Desert, the Gibson Desert (a laterite-covered plain), and the Nullarborslatten. A plains area to the south is the Great Victoria Desert.
According to COUNTRYAAH, large Australian pelvic area extends east of the plateau and shield region and is divided by thresholds in the Carpentaria Basin, partly sea-covered, and the Eyreb Creek with wavy desert plains, partly with pebble and silicon deposits. Lake Eyres, with the country’s lowest point (14 m uh), as well as several other salt lakes (eg Lake Torrenssjön) and plaster deposits originate from rainy periods in the Pleistocene. The large Murray basin in the southeast, with extensive fossil dune fields, is crossed by Murray and its tributary Darling, which dewater the mountains to the east with their snow fields and is the only permanent river system in the area. There are also smaller elevation areas in the central pelvic area. The Flindersbergen and Mount Lofty ridge adjacent to Spencerviken in the south are long narrow folds and horst formations in the powerful sedimentary rocks of the Adelaide geosynclinic.
The eastern highlands extend from the Cape York Peninsula to Tasmania. It is in the north a culinary country, which goes quite far inland but forms part of the Great Dividing Range, which extends from Brisbane along the coast and reaches its highest altitude in the Australian Alps between Melbourne and Canberra, with the summit of Mount Kosciuszko (2,228 m).hrs.). The north-south geosyncline was folded in Late Paleozoic times. Lava plains and granite battolites with block fields are common. Other features of the Great Empire are penal planes from Mesozoic, laterite formations from the middle tertiary, and glacial traces from the Pleistocene glaciers within the Kosciuszko area and Tasmania’s central plateau. The large barrier reef off the coast of Queensland is related to pleistocene sea surface changes but also to a slow subsidence of the seabed.
The position at the tropic gives the country a tropical and subtropical climate with little rainfall. Two-thirds of the area receives less than 500 mm per year, half of it less than 250 mm; 10% of the country receives more than 1,000 mm per year, the highest parts of the southeast in the form of snow, which during winter covers an area larger than Switzerland. Precipitation in the interior is very irregular, which is why long dry periods, but also rainfall, can occur.
Soil formation is also strongly influenced by rainfall conditions. Thus, black soil and brown soil occur where the annual rainfall is 300–500 mm, while leaching and formation of pod sun occur in moist parts. Because the vegetation cover in large areas is missing or sparse, humus content in the soil becomes low and soil erosion becomes a difficult problem.
Plant-and animal life
Australia is divided into a number of ecoregions (see map).
Desert and dry bush landscape
From central Australia to the west coast, the largest eco-region extends to the surface with deserts, steppes and dry bushlands. Extreme variations in temperature and precipitation create difficult conditions for both plants and animals. Among the mammals are rabbit purse badgers, mules, marsupials and wild dromedaries. Despite the extreme conditions, most wilderness species are found here in the world.
To the south extends Great Victoria, Australia’s largest contiguous desert, and in the middle of the ecoregion lies Ayers Rock, one of the country’s most famous landmarks.
At the far west is Shark Bay with a rich marine life, including one of the world’s largest areas of seagrass and ancient stromatolites (pillar-shaped structures built by microorganisms 3 500 million years ago). The rich presence of sharks, such as tiger sharks and hammer sharks, has given rise to the name, but Shark Bay is especially famous for one of the world’s largest stock of dugong of about 11,000 individuals. One of the area’s major tourist attractions is a group of boars, who regularly visit Monkey Mia and are completely fearless to humans. Shark Bay is regularly frequented by humpback whales, southern hijackers, mushroom turtles andcareless tortoise turtle. The rich nutrient conditions also attract large numbers of different birds such as Australian Pied Cormorant (Phalacrocorax varius), pelicans, oystercatchers, little tern, sotstrandskata (Haematopus fuliginosus), banded stilt (Cladorhynchus leucocephalus), wedge-tailed shearwater (Puffinus pacificus), Osprey, White-bellied Sea Eagle (Haliaeetus leucogaster), steeple, rose tern and silver gull (Chroicocephalus novaehollandiae). On two of the islands you will find one of the smallest kangaroo species, western harvallaby (Lagorchestes hirsutus), which once existed in widespread use in Western Australia, but were forced back due to human activities such as bush fires and the planting of foxes and rabbits from Europe.
Tropical and subtropical grasslands, savannas and bush landscapes
In northern Australia, tropical and subtropical grasslands, savannas and bush landscapes are spreading out into the southeastern parts of the country. In the northern parts, it rains abundantly during the monsoon period between November and March/April, while the areas further south are more precipitous.
In the Kakadu National Park in the Northern Territory, rivers from the Arnhem Plateau form huge wetlands, mangrove forests and tidal zones with delta crocodile and freshwater crocodile (Crocodylus johnstoni). Along the coast there is dugong. No less than 2,000 plants have been described within the national park, making the area one of the country’s richest.
It has been estimated that up to 5 million birds visit Kakadu; treasure goose, migratory whales (Dendrocygna arcuata), Australian stilt runner (Himantopus leucocephalus), medium heron (Egretta intermedia) and dwarf pov (Numenius minutus) are most common. Other characteristic species are bearded gib (Threskiornis spinicollis), bronze sib, Australian ibis (Threskiornis moluccus), Australian spoon stork (Platalea regia), black and white heron (Egretta picata) and Pacific black duck (Anas superciliosa). During winter, waders come from Eurasia, among other thingsred poppy, small spaw, coastal pepper, tip-tailed snail (Calidris acuminata), terex snap, red-necked snail (Calidris ruficollis) and colimi snap (Calidris tenuirostris).
Up on the Arnhem Plateau live other rare and endangered bird species, including puffins (Petrophassa rufipennis), gouldsamadine, gray falcon (Falco hypoleucos) and red hawk (Erythrotriorchis radiatus) as well as a giant python (Morelia oenpelliensis) that can live longer than 4 m here. Eight different kangaroo species occur in the national park, including three walnut species.
In Cape York, Queensland, Australia’s largest wilderness area is expanding. Here is a rich blend of savannas with various eucalyptus trees, tropical rainforests, mangrove forests, moorlands and river systems with 3,300 different plant species. About 8,000 years ago the peninsula was united with New Guinea, which is why many common species are found among animals and plants. Examples are the group of tree kangaroos with twelve species, ten in New Guinea and two in Queensland. Another is the group of couscous with two species on Cape York. Among the birds are four species of paradise birds, helmet kittens, palm cockatoo (Callocephalon fimbriatum), toro roe angler (Syma torotoro), noble parrot, red-bellied jewel thrush (Pitta brachyura) and papua groundnut (Podargus papuensis).
Lakefield (Rinyirru) National Park is located in southeastern Cape York and is the second largest national park in Australia. It encompasses huge wetland areas with the country’s largest concentrations of delta crocodile and freshwater crocodile. Bird life is rich with species such as brolgatrana (Grus rubicunda), black-necked stork (Ephippiorhynchus asiaticus), kamjacana (Irediparra gallinacea) and the heavily threatened yellow-shouldered parakeet (Psephotus chrysopterygius). In the sea west of Cape York there are neglected bay turtle, southern bastard turtle (Lepidochelys olivacea) and Nator depressus, an endemic species of sea turtle.
Tropical and subtropical rainforests
Along the Queensland coast, from Cairns in the north to the Warginburra peninsula in the south, are three areas of tropical and subtropical rainforests. Together with the rain forests of Madagascar and New Caledonia, they are among the oldest in the world with the roots of Gondwana when Australia was still linked to Antarctica. Among the 4,700 plants, there are many age-old plant groups and species that only live here. Many of the birds (50 percent) and day butterflies (60 percent) are also endemic.
The Wooroonoor south of Cairns houses Australia’s largest, continuous rainforest area with untamed rivers, waterfalls and deep canyons. No less than 500 different tree species have been found. Three endemic ring-tailed rats live here with one species of tree kangaroo, Australia’s rarest frog (Taudactylus rheophilus) and several endemic bird species.
Great Barrier Reef
Along the Queensland coast lies the Great Barrier Reef. With an area of 2,000 km and an area of 348,000 km 2 (slightly larger than Finland), it is the world’s largest coral reef system, but there are also large mangrove forests, seagrass bottoms and over 1,000 smaller islands. The wealth of various animals is enormous: 1,500 species of fish (of which 133 cartilaginous), 450 species of rock coral, 17 species of seaworms, 30 species of whales and colonies of dugong.
Thanks to effective protection, the strain of humpback whales now amounts to more than 10,000 individuals. Two species of dolphins (Sousa chinensis and the recently described Orcaella heinsohni) are subject to special protective measures. Six of the world’s seven sea turtles live here, and the world’s largest colony of turtles is on Raine Island northeast of Cairns. There are also significant seabird colonies with species such as worm sole (Sula dactylatra), brown sole, red-footed sole, brown noddy and black noddy (Anous minutus), herald petrell (Pterodroma heraldica) and red-tailed tropical bird (Phaethon rubricauda).
Temperate deciduous and mixed forests
In southeastern Australia including Tasmania there are temperate deciduous and mixed forests with many different eucalyptus species, but large areas have been cultivated for agricultural purposes and many forest areas are therefore isolated. The Blue Mountains west of Sydney are among the more intact areas on the mainland, while Tasmania houses the largest untouched forests.
The three animals that are primarily associated with this part of Australia are koala, beak and marsupial. Other animal species are Black-tailed Wallaby (Wallabia bicolor), several species of avian purse and three species of vombats. In Tasmania, there are marsupials, a predator big as a smaller dog and previously found on the Australian mainland but extinct by man and through the introduction of dingo. Giant marsupial (Dasyurus maculatus) is another predator found in Tasmania.
Several bird species have their only occurrence in temperate forests, including broad-tailed lyre (Menura alberti), yellow-tailed soot cockatoo (Calyptorhynchus funereus), sailor parakeet (Lathamus discolor) and yellow-tailed parakeet (Polytelis swainsonii). Kookaburra with its laughing sounds is especially common in this part of the country. In Tasmania there are several endemic birds, including Tasmanian tube hen (Tribonyx mortierii) and green rosella (Platycercus caledonicus). On smaller islands around Tasmania, chicken goose nest, dwarf penguin, black-masked cormorant (Phalacrocorax fuscescens), short-tailed lira (Puffinus tenuirostris), frigate storm whale (Pelagodroma marina), and narrow-billed dive-petellar (Pelecanoides urinary matrix).
Between the mainland and Tasmania and in the waters south, a number of reserves have been set aside to protect marine life, including whales (including humpback whales and blue whales) and seabirds that nest on the islands around Antarctica, including gray-tailed albatross (Thalassarche cauta), black-brown albatross (Thalassarche melanophris), migratory albatross, long-winged petrel (Pterodroma macroptera) and white-chested petrel (Procellaria aequinoctialis), herringbone, narrow-billed dive-petal (Pelecanoides urinatrix) and light-headed whale (Pachyptila).
Over 1,300 meters above sea level In the southeastern part of the mainland lies the Australian Alps with treeless bush and grasslands where snow occurs during the winter months (June – August), especially in the Snowy Mountains with Mount Kosciuszko, Australia’s highest mountain (2,228 m asl). Few plant and animal species have adapted to the extreme climate. Among these are the dwarf scorpions, which are the only alpine marsupial. It has a very limited distribution and is acutely threatened, mainly because of the development of ski resorts, negative climate change and the presence of red foxes and wild cats. There are also several unique frogs here, which are also threatened. At lower levels there are mammals, red-tailed poppy (Macropus rufogriseus), black-tailed walaby and a species of vombat. Bird life is sparse with species such as glanssotkakadua (Calyptorhynchus lathami) and larger ghost owl (Ninox strenua).
Temperate grassland, savanna and bush landscape
Between the more coastal, temperate forests of southeastern Australia and the more desert-like inland, a zone of temperate grasslands, savannas and bush landscapes spreads, but much of the region has been cultivated for grain and few natural areas remain. One area of natural steppe vegetation is Riverina in southwestern New South Wales. Here you will find steeper runners (Pedionomus torquatus) and inland poppers (Peltohyas australis) among several other grassland-dependent bird species. No endemic mammals occur. The two Murray and Darling rivers drain off large parts of the ecoregion. Although large parts of the rivers have been affected by man, there are still good populations of a number of special fish, including giant river perch (Maccullochella peelii), yellow river perch (Macquaria ambigua) and brown river perch (Macquaria australasica).
In southwestern Australia, with foothills in South Australia, Victoria and New South Wales, one finds a Mediterranean-type vegetation. The climate is characterized by hot, dry summers and cool, humid winters. Similar vegetation types are found, except in the Mediterranean region, in South Africa, Chile and California. Among the many endemic plants are curry (Eucalyptus diversicolor), which with its 80-90 m is one of the tallest trees in the world. Specific mammals are rat marsupials, a species of marsupials (Dasyurus geoffroi) and a sovereign moth (Cercarsesus concinnus). Endemic birds include, among others, Western avian (Psophodes nigrogularis), Western terrestrial parrot (Pezoporus flaviventris), red-winged blue-breasted (Malurus elegans), white-chested (Eopsaltria georgiana), brown-breasted (Dasyornis longirostris) and long- billed soot cockatoo (Calyptorhynchus baudinii) and short- billed soot cocoa (Calyptorhynchus latirostris).
The extremely good nutritional conditions in the sea around southwestern Australia attract many fish, seabirds and marine mammals. Colonies of Australian sea lions (Neotoma cinerea) attract both white shark and killer whale, and several whales visit the area regularly, including cascade, humpback whale and blue whale. Among the many seabirds are the yellow-billed albatross (Thalassarche carteri), light-footed lira (Puffinus carneipes), velvet petrel (Pterodroma mollis) and wedge- tailed lira.
Australia has a well-developed and organized nature conservation. In 2010, about 10 percent of the country was protected by more than 800 national parks and other major reserves. Among the nature-protected areas is the Great Barrier Reef’s marine park.