Chapter 6b Australia Physical.pdf

Name:_______________________________ Date:____________________________ Section:_________________________ Roll No.:_____________________ La Martiniere Girls’ College Class VII...

Name:_______________________________ Date:____________________________ Section:_________________________ Roll No.:_____________________ La Martiniere Girls’ College Class VII Geography Chapter 6b Australia: Physical Features Australia derived its name from Latin word ‘Australis’ which means Southern. It is called an island continent because it is surrounded by oceans and seas on all sides and also includes the island of Tasmania and many small islands. It is the largest island in the world which is a country and continent itself. Australia is one of the lowest and flattest of the continents. It has no high mountain ranges like the Himalayas or the Alps, deep valley like that of the Brahmaputra or large rivers like the Amazon. Its highest peak, Mt. Kosciuszko, is just 2,228 m above sea level. LMGC/CL7/GEOGRAPHY/ChNo.6 b Page 1 of 7 The term Australasia includes Australia, New Zealand and the neighbouring islands of the South Pacific Ocean. It is also called Oceania. The coastline is smooth with almost no inlet except in the South. Thus, Australia has very few good harbours. Australia is a land of varied physical features; divided into four main categories:  The Great Western Plateau The Central Lowlands The Eastern Highlands The Coastal Plains 1. The Great Western Plateau Located in the western part of the Continent, this plateau covers nearly two-thirds of Australia. It is made up of a huge block of ancient rock. Following are some main features of the vast plateau. The Deserts Almost 70% of the region is covered by deserts. The central part of the plateau is covered by three deserts- the Great Sandy, the Gibson and the Great Victoria Desert. Sand dunes, sandy plains and salt lakes cover most of the surface. Rainfall is very scanty in this region. The Nullarbor Plain To the south of the deserts, and north of the Coastline, lies the Nullarbor plain. This area is flat and treeless (‘Nullarbor’ comes from Latin words – ‘nullus’ meaning ‘no’ and ‘arbor’ meaning ‘tree’). There are huge underground caverns formed by water flowing through the lime stone rocks Stalactites and Stalagmites are the striking features in these plains. The Mountains Ranges and Plateaus Several mountain ranges dot the Great Western Plateau. Of these, the King Leopold Ranges lie in the north. The Hamersley Range, which has some of the largest deposits of iron ore in Australia, lies towards the West. The Musgrave and MacDonnell Ranges lie in the central part of the plateau. Between the two ranges stands Uluru or Ayers Rock. Uluru, with a height of 348m, is one of the largest inselbergs in the world. An inselberg, also known island mountain, is an isolated residual hill that rises sharply from the surrounding areas. LMGC/CL7/GEOGRAPHY/ChNo.6 b Page 2 of 7 The Rift Valley System A special feature of the plateau region is the Rift Valley System located in the region around Adelaide. There are several block mountains here, like Mount Lofty, Flinders Ranges and the Barrier Range. The river valleys have been filled up by the sea. They include Spencer Gulf and Gulf of Saint Vincent.A rift valley is formed when a part of the land subsides/sinks between two parallel cracks. 2. The Central Lowlands LMGC/CL7/GEOGRAPHY/ChNo.6 b Page 3 of 7 The Central Lowlands is a low-lying region between the Western Plateaus and the Eastern Highlands. The region can be divided into three lowlands- the Carpentaria Basin, Lake Eyre Basin and the Murray-Darling Basin. The Carpentaria Basin This basin occupies the northern part of the Central Lowlands. This region is drained by the rivers Gregory, Leichardt and Flinders, all of which flow northwards into the Gulf of Carpentaria. The Lake Eyre Basin The lake Eyre Basin in south-central Australia is a vast region of inland drainage. It is drained by a number of rivers all of which flow towards Lake Eyre, a salt water lake. The rivers flow very slowly and evaporation is so high that during the dry season, the rivers dry up and leave behind shiny salt flats and lakes. During periods of heavy rainfall, the rivers flow into Lake Eyre and Lake Yamma Yamma. The Murray- Darling Basin In the southern part of the Central Plains lies in the Murray- Darling Basin. It is drained by the Murray River and its tributaries, the Darling and Murrumbidgee rivers. These rivers carry huge amounts of silt that they deposit over the plain making it very fertile. The Murray- Darling Basin is one of the most important agricultural regions of Australia. 3. The Eastern Highlands The Eastern Highlands stretches for around 3,700km along the eastern edge of Australia. The Eastern Highland act as a watershed. Rivers flow eastwards towards the Pacific or westward towards the Central Lowland. Therefore, the Eastern Highland are called The Great Diving Range. The rivers of the Eastern Highland are important in many ways: i. The rivers drain the eastern coastal plains and make it fertile for agriculture. ii. They make waterfalls and help in the generation of Hydel power. iii. These rivers also help in navigation. iv. The rivers provide water throughout the year as they are fed by the melting snow as well as by the monsoon rain. 4. The Coastal Plains The Coastal Plains is a narrow strip of flat land that stretches along the Eastern coast of Australia and Queensland to Victoria. This area receives relatively high rainfall. Most of Australia’s main cities, including Brisbane, Sydney and Melbourne, are located along the coastal plains. Therefore, this is the most densely populated region of Australia. The Great Artesian Basin The Great Artesian Basin of Australia is one of the largest artesian basins in the world. It lies between two highlands- the Eastern Highlands and the Western Plateau- this region barely gets any rainfall. However, enough water is available for cattle and sheep rearing because of the underlying artesian basin. LMGC/CL7/GEOGRAPHY/ChNo.6 b Page 4 of 7  An artesian basin is a saucer- shaped aquifer. An aquifer is a layer of porous rock which holds large amounts of water, sandwiched between two layers of impermeable rock. Rain water steeps into the aquifer and move downwards due to the force of gravity until it reaches the lowest part of the basin. The impermeable layers above and below the aquifer do not allow the water to escape upwards or downwards. The Great Barrier Reef The Great Barrier Reef is the largest coral reef in the world and one of its natural wonders. It is formed by millions of tiny living creatures called coral polyps. The 2,000 km long Great Barrier Reef lies along the east coast of Queensland in the Pacific Ocean. Since this reef clings to the margin of the land, it is called a fringing reef. The Great Barrier Reef is home to a number of marine plants and animals. Various species of whales, dolphins, turtles and porpoises can be found in the Reef. Almost 10% of the world’s entire fish population is also found here. The reef attracts a lot of tourists who can wade or scuba diver, or sail in boats with transparent viewing floors. The underwater coral gardens have a wide variety of fish swimming around. But bigger ships like tankers and liners cannot sail in these waters as the sharp coral can rip the bottom of the ships. Important terms: i. Glacier- A slow-moving body of ice. ii. Geyser – Jets of hot water and steam spouting out automatically at regular intervals. iii. Fjord – A long narrow inlet with steep sides or cliffs, created in a valley carved by glacial activity. iv. Artesian basin – A flat land where a layer of permeable or porous rock is sandwiched between two layers or impermeable rocks v. Artesian well – A well from which water gushes continuously. vi. Aquifer – A water holding layer of rock. vii. Downs – Fertile temperate grasslands. viii. Coral - A hard substance formed from the skeletons of coral polyps. ix. Inland drainage area – An area where rivers do not drain into the sea, but into an inland lake. x. Barrier reef – Shallow ridges in the sea (generally near the coast) made of coral polyps. xi. Watershed - a dividing ridge between drainage areas LMGC/CL7/GEOGRAPHY/ChNo.6 b Page 5 of 7  QUESTIONS AND ANSWERS Q1 What is meant by the term ‘Australasia’? What is another name given to it? Q2 Write a short note on the Great Artesian Basin of Australia, and draw the diagram. Q3 Write a note on the Eastern Highlands. Q4 How did Australia derive its name? Why is it called an island continent? Q5 The rivers of the Eastern highlands of Australia are important to us. Justify. Q6 Choose the correct answer: a. Which of the following statements is true about the Great Western Plateau? i) It covers nearly two-thirds of Australia. ii) It is located in the eastern part of the continent. iii) It is made up of a huge block of ancient rock. iv) It includes the Great Barrier Reef. Options: a) i, ii, and iii b) i, iii, and iv c) ii, iii, and iv d) i, iii, and iv b. Which deserts are part of the Great Western Plateau? i) The Great Sandy Desert ii) The Gibson Desert iii) The Great Victoria Desert iv) The Simpson Desert Options: a) i, ii, and iii b) i, ii, and iv c) ii, iii, and iv d) i, iii, and iv c. What is unique about the Nullarbor Plain? i) It is flat and treeless. ii) It contains huge underground caverns. iii) It is located in the north of Australia. iv) It is rich in iron ore deposits. Options: a) i, ii, and iii b) i, ii, and iv c) ii, iii, and iv d) i, ii, and iv d. Which of the following are part of the Central Lowlands? i) The Carpentaria Basin ii) The Lake Eyre Basin iii) The Murray-Darling Basin iv) The Nullarbor Plain Options: a) i, ii, and iii b) i, ii, and iv c) ii, iii, and iv d) i, iii, and iv LMGC/CL7/GEOGRAPHY/ChNo.6 b Page 6 of 7  e. Which rivers drain the Carpentaria Basin? i) The Gregory River ii) The Leichardt River iii) The Flinders River iv) The Murray River Options: a) i, ii, and iii b) i, ii, and iv c) ii, iii, and iv d) i, iii, and iv Q7 Assertion and Reasoning question: Read the two statements given below and select the option that shows the correct relation between (A) and (R). i. Assertion (A): Australia is called an island continent. Reason (R): It is surrounded by oceans and seas on all sides and includes the island of Tasmania. a. Both A and R are true and R is the correct explanation of A. b. Both A and R are true but R is not the correct explanation of A. c. A is true but R is false. d. A is false but R is true. ii. Assertion (A): The Nullarbor Plain is a flat and treeless area. Reason (R): The name 'Nullarbor' comes from the Latin words meaning 'no trees'. a. Both A and R are true and R is the correct explanation of A. b. Both A and R are true but R is not the correct explanation of A. c. A is true but R is false. d. A is false but R is true. Q8 Choose the correct option to match the following: 1 Eastern Highlands i Known as the Great Dividing Range 2 Coastal Plains ii Receives relatively high rainfall 3 Murray River iii Important for agriculture in the Murray-Darling Basin 4 Great Barrier Reef iv Largest coral reef in the world a. 1-i, 2-ii, 3-iv, 4-iii b. 1-ii, 2-iv, 3-i, 4-iii c. 1-i, 2-ii, 3-iii, 4-iv d. 1-iv, 2-ii, 3-iii, 4-i Q9 Thinking Skills: The Great Barrier Reef is mentioned as the largest coral reef in the world and a major tourist attraction. Considering its ecological importance, what are some potential environmental threats to the Great Barrier Reef, and what measures could be taken to avoid these threats? LMGC/CL7/GEOGRAPHY/ChNo.6 b Page 7 of 7