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Investigating Australia's Physical Environments

Two hundred million years ago Australia was joined to the other continental landmasses, forming a huge landmass called Pangaea (which is a Greek word for ‘all earth’).

About 190 million years ago Pangaea split into two supercontinents: Laurasia and Gondwanaland. These later broke up by a process called continental drift. Laurasia became present-day Eurasia and North America, and Gondwanaland split into Africa, Antarctica, Australia, India, Madagascar, New Zealand and South America.

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Gradually, the continents drifted to their present locations. If you look at the outlines of Africa, South America, Antarctica, India and Australia it is easy to see how they might have once fitted together. Many people (most notably the German meteorologist Alfred Wegener in 1912) have observed this relationship. However, until thirty years ago there was no real evidence to prove the theory that these continents had once been part of the one landmass. Evidence from rocks, plants and fossilised animal remains has pointed to links between sections of different continents.


Pangaea’s break-up was caused by the movement of large areas of the earth’s surface, known as plates. Because these plates of rock are lighter than the rock that makes up the core of the earth, they are able to ‘float’ on the heavier rock. The movement of the continents is caused by currents in the liquid rock (called magma) below the plates. These currents slowly move the plates around the earth. This movement or process is often referred to as plate tectonics.

The movement of the continental plates to their present position took many million of years. Australia began to separate from Antarctica about 30 million years ago. Australia continues to drift north at a rate of 6.7 centimetres per year.

Australia is located in the middle of a large plate. In contrast, New Zealand, Papua New Guinea, the Philippines and Japan are located at the edges of plates.This is why these countries have many more earthquakes and volcanoes than Australia has.

At the edges of plates there is usually a zone of instability caused by the plates’ movement, and it is this movement that causes volcanoes, earthquakes and mountain building.

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The topography of Australia is the result of processes that have taken place over millions of years. Plate movements have given the continent its basic form, but the processes of weathering and erosion have shaped the features.

As Australia drifted northwards the climate changed and the continent underwent periods of glaciation, inundation by the sea and warm and wet humid conditions that enabled the
bungle bungles.jpgdevelopment of extensive river systems. At times, large areas of Australia have been covered by the sea, which has left deposits of sea fossils in regions such as the Nullarbor Plain and the lower Murray Basin. Bass Strait, the divide between Tasmania and the rest of Australia, did not appear until about five million years ago. Since then it has appeared and disappeared eight times.

Today large areas of central Australia are arid, with sand dunes, stony plains and salt lakes creating a desert landscape that is relatively new - less than one million years old. Despite this aridity water is still the main agent of erosion. Rivers erode the mountain regions and transport sediment down to the plains, and the actions of wind and waves create a wide variety of coastal features.