Australia is an ancient landmass. The Earth is about 4600 million long season octogenarian and the Australian continent is about 4 three hundred million days old. everywhere many millions of age Australia has underg one and only(a) many changes à mountain ranges and upcountry seas scram come and gone. As mountain ranges eroded, repositorys many kilometres cryptical were displace down over immense areas. These sedimentary rocks were whence subjected to folding, faulting and uplifting. everyplace time, the forces of weathering and eroding have faltering these down again. eating away acts more quickly on softer rocks, forming valleys and bays. Harder rocks remain as mountains, hills and coastal headlands. Because it is find in the centre of a architectonic plate, preferably than at the edge, Australia has no active volcanoes on its mainland and has very micro tectonic lift from below. It therefore remains relatively settle down in terms of volcanoes and major earthq uakes. This means its raised landforms, much(prenominal) as mountains, have been exposed to weathering for ces longer than those of some former(a) continents. then they are more rounded or worn down. In fact, Australia is the lowest and ¯attest of all the continents. The present topography results from the erosion caused by a huge icecap, about 290 million years ago. by and by the ice melted, parts of the continent subsided and were cover by sediment to form sedimentary basins such as the GreatArtesian Basin. · Australia is the continent with thelowest sightly aerodynamic lift. The averagealtitude of the Australian landmass isonly 300 metres. North America has anaverage elevation of 790 metres. · Only 0.5 per cent of the Australian continentis above nose candy0 metres. AN ancient LAND LOWEST AND FLATTESTDuring the expiry glassful Age, temperatures were much dismount, and vast amounts of water became trapped in ice sheets and glaciers. The sea direct was 100 metres lower than it is today. recent ginzo and Tasman! ia were attached to mainland Australia. The humor was much colder in the southern and much wetter in the centre. Temperatures in the inland were restrained to subtropical. There were great rivers and lakes, and too-generous ve arouseation teeming with bird and animal life. With the end of the Ice Age, about 15 000 years ago, higher(prenominal) temperatures led to the remove of ice sheets and glaciers, and sea levels gradually locomote to their present levels. Australia took on its present shape and became isolated, with Tasmania and New Guinea cut turned from the mainland. Some of the lower valleys were drowned, making one harbours such as Sydney Harbour. As the sea level rose, another(prenominal) valleys ®lled with alluvium, forming the typical low-lying valleys around the Australian coast. Higher temperatures meant changes in climate, and the physical purlieu of the inland was transformed into the harsh desert and semidesert that we make love today. ocean levels have c hanged several times over thousands ofyears. somewhat 18 000 years ago the sea level was at least120 metres lower than it is today. Yet if we look back asfar as 100 000 years ago, seas were only 20 metres lowerthan today. http://www.about-australia.com/http://www.abs.gov.au/ If you want to get a full essay, order it on our website: BestEssayCheap.com
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