Geography of Australia : Physical Divisions,Climatic zones

Geography of Australia

Thousands of islands combine to form Oceania region mostlycovering the Central and South Pacific Ocean. The region is dominated by world’s biggest island and two other major landmasses, micro-continent of Zealandia ( includes New Zealand) and the western half of the island of New Guinea, made up of the nation of Papua New Guinea. Oceania also includes three island regions: Melanesia, Micronesia, and Polynesia (including the U.S. state of Hawaii).

It stretches from the Strait of Malacca to the coast of Americas. Tropic of Capricorn divides it into almost two halves.

Australia is the world’s largest island and smallest continent.

• It is the only nation that completely covers a continent.

• Its total area is nearly double that of India and Pakistan combined.

• It lies entirely in the Southern Hemisphere and is aptly named – Austral meaning south.

• It is located between the Indian and Pacific Oceans,stretches west to east from 114°E longitude to 154°E longitude and from 10°S to 40°S latitude.

• The Tropic of Capricorn cuts the continent almost into half.

• Asia is the continent nearest to Australia.

• The nearest point on the mainland of Asia is Singapore

• To the west of Australia, Indian Ocean, to the south, the icy shore of Antarctica to the south-east is New Zealand.To the north-west is the continent of Asia.

Physical Divisions

Australia is the most levelled and lowest of all the continents.

There are no high mountains, deep valleys or large rivers. Mount Kosciusko 2,230 metres above sea level, is the highest peak.

The coastline is very smooth with no inlets except in the south.

So there are very few good harbours. As a smallest confinent Australia has no prominent physical division. yet efforts have been made to divide it roughly into four categories, such as:

Eastern Highland

This is a chain of hills and mountains which interrupts the levelled land form of Australia. These are also known as great Dividing Range.

The Great Dividing Range

• It is, also known as the Easter Highlands, is Australia’s most substantial mountain range. The range stretches more than 3500 km from the northeastern tip of Queens land,running the entire length of the eastern coastline through New South Wales, then into Victoria and turning water,before finally fading into the central plain at the Grampians in western Victoria.

• The Great Dividing Range does not consist of a single mountain range. It consists of a complex of mountain ranges, plateau, upland areas and escarpments with an ancient and complex geological history.

• The crest of the range is defined by the watershed or boundary between the drainage basins of rivers which drain directly eastward into the Pacific Ocean, and those rivers which drain into the Murray-Darling River system towards the west. In the north, the rivers on the west side of the range drain towards the Gulf of Carpentaria.

The Western Plateau

This eroded plateau has undergone the process of erosion for a quite longer period. It is characterised by several ‘sinkhole’a network of underground caves which filled with water. The Western plateau is also called as the home for serveral deserts and the climate is comparatively dry owing to the cold water current of the western Australia. The series of desert in this region are:

• The ranges were originally home to Australian Aboriginal tribes such as the kulin.

Desert

Gibson Desert – a central Australian desert

Great Sandy Desert – a northwestern Australian desert • Great Victoria Desert – the sixth largest desert in the world by area, located in south-central Australia.

Simpson Desert – a central Australian desert

Little Sandy Desert – a western Australian desert

Strzelecki Desert – a south-central Australian desert

Tanami Desert – a northern Australian desert

Western Desert – a desert located in western Australia,comprising the Gibson, Great Sandy, and Little Sandy deserts.

Rangipo Desert – a barren light altitude desert on the North Island Volcanic Plateau in New Zealand.

The Central Lowland

The extensive patch of plain or low land has its existence between Eastern Highlands and Western Plateau. The patch is drained by two rivers such as Murray and Darling which also facilitate the land with irrigation facility for farming and other essential activities. The area is also known as the Great Artesian Basin as it is covered by a number of underground pressurized wells from which the water comes out automatically to the surface.

Yet they are not suitable for drinking as they are salty by nature.

The Great Barrier Reef

• This is the largest coral reef in the world.

• It lies along the east coast of Queensland, Australia, in the Pacific Ocean.

• It is about 2,000 kilometres long, in some places it is as close as 16 kilometres to the coast while in other places

it is 200 kilometres away.

• It is one of the natural wonders of the world.

• It is formed by the tiny coral polyps.

The Islands

The islands situated surrounding the younger most continent

in size is collectively known as Oceania. Broadly it has been

divided into three major island groups Melanesia, Micronesia and Polynesia.

Melanesia is otherwise known as Black Islands and congregated around north and east of Australia. Some of the major islands are East Timor, Fiji, New Caledonia, Papua New Guinea, Solomon Islands, and Vanuatu.

Micronesia which is also called as Little Islands is the agglomeration of islands such as Guam, Kiribati, Marshall Islands, Federated States of Micronesia, Nauru, Northern Mariana Islands, Palau and Wake Island Polynesia otherwise known as Many Lands which expand from islands of Midway in the north to New Zealand in south and include the series of islands such as American Samoa Cook Islands, French Polynesia, Niue, Pitcairn , Tokelau, Tonga,Tuvalu, Wallis and Futuna Islands.

The islands of Ocenai have been formed due to differential activities of volcanoes. The low islands of Micronesia have been formed by building up coral reefs on the rim of volcanic island,hence giving it a shape of a Ring which is known as Atolls. The atolls further encircles the lagoons which are characterised by shallow pools of clear water at a very low altitude of just few feet above sea level.

Drainage System

Australia has low average rainfall.

• Being a hot dry country the rate of evaporation is high. So there is very little water left to flow as river to the sea.

• As a result of this the total dustrian continent is mainly drained by two of the largest drainage barins Murray and Darlias and an inland lake in also found which is knwon as lake Eyre Basin. Which accounts an area for over 1 million square kilometre.

• River Murray starts from the Snowy Mountains of the Great Dividing Range.

• Its tributaries are the Darling, Murrumbidgee and Lachlan.

Many dams have been built across these to provide for irrigation and power generation.

• River Swan near Perth is also utilized in the same way.

Climatic zones

There are generally four types of wind prevail over Australian continent through out the year which affect the climate of the little continent to a large extent.

Seasonal change in the Temperate Zones

The coastal hinterland of New South Wales, much of Victoria,Tasmania, the south-eastern corner of South Australia and the south-west of Western Australia are contributing the temperate zones where the seasonal changes are as follows

Summer: December to February

Autumn: March to May

Winter: June to August

Spring: September to November

The two similarly affected areas to that of temperate zones are:

• The temperate grassland that surrounds the arid and semi-arid desert areas in the centre and gradually percolates into the area north of Alice Springs in the Northern Territory.

• Desserts are the arid and semi arid areas of the centre of the continent which stretch across the vast amount of South Australia and Western Australia.

Seasonal change in the Tropical Zones

There are three climatic zones in the tropical areas of Australia:

• Equatorial – the tip of Cape York and Bathurst and Melville Islands north of Darwin.

• Tropical – across northern Australia including Cape York,the Top End of the Northern Territory, land south of the Gulf of Carpentaria, and the Kimberley region.

• Sub-tropical – the coastal and inland fringe from Cairns along the Queensland coast and hinterland to the northern areas of New South Wales and the coastal fringe north of Perth to Geraldton in Western Australia.

These above mentioned areas experience two exactly opposite spell of season i.e. wet and dry seasons.

The wet season is otherwise called as the monsoon season,which lasts about six months, between November and March. The temperature ranges between 30 and 50 degrees Celsius and comparatively it is hotter than the dry season because of the high humidity during the wet, which is caused by large amounts of water in the air. It is also marked by heavy rainfall which leads to frequent flooding.

The dry season lasts about six months, usually between April and October. Temperatures are lower and the are generally clearer during the dry. The average temperature is around 20 degrees Celsius.

Natural Vegetation

Downs

• The temperate grassland of Australia known as downs is found in the Murray-Darling basins of South Eastern part.

• They are largely used for pastoral activity.

• Cultivation is profitably done in the down areas where Mitchel grasses grown.

• The Mitchel grasses grow even on the cracking clay soils,basaltic soils, and even on skeletal soils.

• Similarly Canterbury grassland is found in New Zealand.

The tropical Rain forest island regions

These are home to dense forests with coconut palms and mangroves growing nearer the shorelines. High temperatures throughout the year with very little rainfall.

The deciduous forest region

It has a wealth of plant life and includes tall and short trees, shrubs,small plants and mosses. Four distinct seasons with warm summers and cold, wet winters. The trees shed their leaves in autumn.

Savanna

Very high temperatures all year and rain during the summer season only.

The dry desert and desert scrub region

It is home to the eucalyptus as well as those plants that can survive the arid conditions like cactii. Warm to high temperatures with very little rainfall. Hot summers and cold winters with above average rainfall.

The varying climate of Australia is largely dependent its size.

The temperature ranges below zero in the Snowy Mountains in southern Australia to extreme heat in the Kimberley region in the north-west of the continent. Different climatic zones are characterized by distinct climatic phenomena with prominent

seasonal changes

Four prominent seasons such as Summer, Autumn, Winter, and Spring are experienced in the Temperate zone, Desert and the Grassland climatic zones but drastically it has changed to wet and dry seasons in the tropical north of the continent which includes the Equatorial, Tropical and sub-tropical zones.

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