UNIT 1 PHYSICAL SETTINGS Structure 1.0 Objectives I. I Introduction 1.2 Geographical History 1.3 Physical Geography 1.3. 1 I.alldli,rms 1.3.3 Clinlatc 1.3.3 Drainage 1.3.4 llivers and Lakes 1.3.5 Soils 1.4 Settlement I'atterns 1.5 Historical Evolution 1.6 Let US Sum Up 1.7 Key Words 1.8 Some Useful Books 1.9 Answers to Check Your Progress Exercises 1.0 OBJECTIVES It is essential, for a proper understanding of the government and the politics of a country to have some idea of its geographical settings, its history and socio-economic system. In this unit you will be acquainted with the physical geography of Australia. After studying the unit, you will be able to: trace the geographical history of Australia; I describe the topography of Australia; identify the fauna and flora of Australia; explain the settlement patterns; and explain the evolution of modern Australia. 1.1 INTRODUCTION In this unit we shall study the physical geography of Australia . Australia is the only nation that occupies an entire continent. With an area of 7,682,300 square kilometers it is the sixth largest country:in the area after Russia, Canada, China, the United States, and Brazil. Australia known as the island continent is slightly more than twice the size of India. It lies to the east between longitudes 1 13O9' and 153O39' and between the south latitude of 1 0°4 1 ' and 43'39'. The Tropic of Capricorn passes almost through the middle of the continent. It has a 36.735 km. long coastline. The continental shelf extends north to Papua New Guinea and south around Tasmania, varying in width from about 30km to more than 240km. Just off the eastern cbast the Great Barrier Reef extends north for 2000km from Southern Queensland to the Gulf of Papua. Enclosing about 207,000 square kilometers, the reef is an important marine ecosystem, a complex of islands and coral reefs containing many rare life forms. Australia-is one of the oldest land masses; the continental bedrock exposed by erosion is more than 3 billion years old, and Australia is the flattest of the continents. After Antarctica, it has the lowest precipitation rate in any continent. The mean annual rainfall is 465mm. Vast areas are arid or semi-arid and unsuitable for settlement. The average elevation is lkss than 300m, compared with the world's mean of about 700m. The Australian Alps in the southeast is Australia's highest ground. The highest peak being Mount Kosciusko (2228m). The main structural feature, the Great Western Plateau, extends over most of Western Australia, much of the Nortliern Territory and South Australia, and part of western Queensland. Introducing Australia Other significant outcrops include Uluru (Ayers Rock), a monolith 8km in circumference rising 335m above the central Australian desert. Uluru changes colour as the sun changes position in the sky. Nearly a third of the Australian continent lies in the tropics, and the rest is in the temperate zone. The coldest regions are in the south eastern corner of the mainland, where the'only ' regular snowfall occurs. Australia consists of six states and two self-governing territories. The States are: Queensland, New South Wales, Victoria, Tasmania, South Australia and Western Australia. There are two territories viz. Northern Territory and Australian Capital Territory. New South Wales has the highest population (6.20 million) followed by Victoria (4.56 million). The following Table shows the area and population of different stateslterritories: StatesITerritories Area in km sq. Population Capital Queensland 1 730 648 3.34111 Brisbane (1.52111) I New South Wales 1 800 642 I 6.20m Sydney (3.88m) Victoria Melbourne (3.28m) .Tasman ia Hobart (0.20m) South Australia Adelaide (1.08111) I Western Australia 1 2 529 875 1 1.771~1 Perth (1.301n) I Northern Territory I 1349 129 1Q.18m Darwin (O.08m) I Australian Capital Territory 1 2 43 1 I 0.31m Canberra (0.3 1 m) AUSTRALIA 7 692 024 18.3m a 1.2 GEOGRAPHICAL HISTORY Australia was known to the Western World only during the recent centuries. Though the Australian landmass is different from the landmass of America, it strongly resembles the continents of Asia, Europe and Africa. There are three kinds of structural parts in Australia, such as the Western Australian Shield, Eastern Fold mountain belt, and the central plains. The Western Australian Shield IS a comparatively stable and strong block. Though the eastern belt suffered from erosion, it is relatively uplifted. In between the east and the west lies the plain land which resembles a platform. Australia in shape and outline looks almost like the moon on the tenth day of the light fortnight. The South-west which is a part of the Western Australian Shield, consists of the oldest rocks in the continent. The oldest rocks are considered to be about 3,000,000,000 years old. These rocks have remained unfolded since the Precambrian age. The examination of the rocks show that originally they were very different from what we sek today. In the west and south coasts of western Australia there exists younger Precambrian rocks which are 2000,000,000 to 2,500,000,000 years old. > Old rocks are also to be found on the border of Kimberley Block and in the Katherine - Darwin regions of the Northern territory, in the Run jungle complex. The age of the rocks in the east has yet to be calculated. Central Australia may be approximately 2,250,000,000 years ,' old. Check Your Progress 1 Note: i) Use space provided below each question to write your answer. @ ii) Check your answer with the short model answers given at the end of the unit. / F I ) Trace the geographical history of Australia. Physical Sctti~~gs ! 1.3 PHYSICAL GEOGRAPHY I Australia is a land both flat and dry. Th~llgbit is flat there is not much uniformity in the landscape. It is an arid land. Only one-third 6f the ccl'htineat gets more than 20 inches rainfall per annum average. Perennial rivers are to be found only in eastern Australia and in Tasmania. 'The climate of Australia has had a tremendous role to play in soil formation and composition. 1.3.1 Landforms Australfa is the lowest, flattest and, apart hotti Antarctica, the driest of all the continents. Unlike Europe and North America. where some landscape8 date back to 'only' 20,000 years ago, when great ice sheets retreated, the age of landforms in Australia is generally measured in many mlllions of years. This fact gives Australia L iery cli&r.ctive physical geography. The continent can be divided into three parts: the Western Plateau; the Central Lowlands; and the Eastern Highlands. The Western part of Australia is a vast plateau. It occupies hearly two-thirds of the continent. It consists of very old rocks (some over 3,000 million years old), and much of it has existed as a landmass for over 500 mill~onyears. Several parts have individual plateau names (e.g. Kimberley. I-lammersley, Arnhem Land, Yilgarn). In the Perth area, younger rocks along a coastal str~pare separated from the rest by the Darling Fault escarpment. The Nullabor Plain is virtually an uplifted sea floor, a limestone plain of Miocene age (about 25 million years). Most of the plateau is desert or semi-desert. Mostly it is flat and covered with small shrubs. The Central Lowlands stretch from the Gulf of Carpentaria through the Great Artesian Basin to the Murray-Darling Plains i.e. southern shores of Australia. The Great Artesian Basin is filled with sedimentary rocks which holds the water that enters the wetter Eastern Highlands. Much of the centre of Australia is flat, but there are numerous ranges (e.g. Macdonnels, Musgl-ave) and some individual mountains of which Uluru iAyers Rock) is probably the best known. Faulting and folding in this area took place long ago. In the southern australian part of the Central Lowlands, fault movements are more recent, and the area can be considered as a number of blocks that have been moved up and down to form a series of ranges (Mt Lofty, Flinders Ranges) and hills (such as the Adelaide Hills), with the comes faulted blocks occupied by sea (e.g. Spencer Gulf) or lowlands including the lower Murray Plains. The average elevation of the region is less than 150 meters. At Lake Eyre it is about 12 meters below sea level. Owing to scanty rains much of the lowland is very dry. Some water is obta~nedfrom the Artesian wells, dug deep into the ground and the water flows out contin~~ouslyand automatically. Most of the rivers flowi~igthrough this lowland do not reach the sea. They flow into inland lakes. 'The Eastern Highlands rise gently from central Australia towards a series of high plateaus, and even the highest part around Mt Kosciuszko (2,228 metres) is part of a plateau. These highlands are found mainly parallel to the east-coast of Australia. They extend from Cape York Peninsula in the north to Tasmania in the South. Introd~~cingAustrnlia There are a few younger faults and folds, such as the Lake George Fault near Canberra, and the Lapstone Monocline near Sydney. Some plateaus in the Eastern Highlands are dissected by erosion into rugged hills, and the eastern edges of the plateaus tend to form high exarpments. Many of these are united to form the Great Escarpment that runs from northern ( 4.:cnsland to the Victorian border. Australia's highest waterfalls (Wollombi on the Macleay, r ''lnlnn Falls on a tributary of the Herbert, Barron Falls near Cairns, and Wentworth Falls I LC Blue Mountains) all occur where rivers flow over the Great Escarpment.