The Unique Australian Environment

Simon K

Between approximately 570 and 510 Million years ago all the continents were attached to one another. The top half or North half of this supercontinent was called Laurasia, while the significantly larger South half was called Gondwana

Gondwana

Gondwana was made up of Antarctica, South America, Africa, Madagascar, Australasia, Arabia and the India subcontinent.

History• During Earth’s 4.6 Billion year history, the

continents have been constantly moving and colliding with other continents. Between 570 and 510 Million years ago the supercontinent Pannotia broke into Laurasia and Gondwana. The two continents drifted apart before colliding again, forming another supercontinent called Pangaea. After forming Pangaea the continents split again, this time forming the present day positions.

• It has taken approximately 250 Million years for Pangaea to separate into the present day positions.

Explanation

• The core of the Earth consists of molten magma, so because the continents “float” on top, they are relatively unstable and will therefore move around and collide with each other. Because the tectonic plates are not attached to one another, the continents are free to split up and then collide again.

• It is basically impossible for the continents to stop drifting, as the core of the Earth will always be molten.

Origins of Australian Animals

• Some Australian animal species that either exist in other continents, or have extremely close ‘relatives’ in other continents, are animals such as lizards, insects, some marine species and some bird life.

• It is also possible that wallabies originated from wallaby species in other continents.

Dinosaurs and Gondwana

• The supercontinent Pannotia (consisting originally of Laurasia and Gondwana) broke up before the time period referred to as ‘the reign of the dinosaurs’. Although their were dinosaurs around, they tended to be small reptiles or birds etc. The dinosaur species were yet to develop into the creatures made famous by Hollywood movies.It is unlikely that the break up of Pangaea led in some way to the extinction of the dinosaurs. The continents drifted apart over Millions of years so while the climate may change gradually over time, any animals inhibiting the continent would have had ample time to adapt.

• As the continents slowly shifted apart and moved into different positions around the globe, the climate of these continents would have also changed dramatically over that long period of time. The temperature would change, depending on where the continent moves in relation to the equator, while the separation of the continents would have changed sea currents, therefore further altering the climatic conditions of various continents.

• In order to survive this gradual climatic change, the plants and animals inhabiting the continents would have had to adapt or they would perish and die out. Adapting may have included not just slowly changing body appearance (e.g growing thicker fur etc), but may have also included changing breeding patterns and hunting patterns etc.

Human Colonisation

• Because the sea levels were far lower in the past than at present, occasional ‘land bridges’ would exist between the different continents. This, along with the fact that some of the smaller land masses continued to drift within a short vicinity to one another, allowed humans to gradually colonise the planet.

• The Aboriginal that later populated Australia were thought to have crossed from South East Asia, when a land bridge existed between the topper-most point of Australia and Papua New Guinea.

• As humans moved to different continents and encountered different climatic conditions, they too were forced to adapt to survive.

Bibliography

Websites

www.wikipedia.com

www.the-great-barrier-reef-experience.com

www.apstas.com

www.australianmuseum.net.au

www.scotese.com