Evolution of Australian Biota

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Evolution of Australian Biota
1. Evidence for the rearrangement of crustal plates and continental drift indicates that Australia was once part of an ancient super continent
Identify and describe evidence that supports the assertion that Australia was once part of a landmass called Gondwana including:
Matching continental margins
Gondwana once consisted of South America, Africa, Madagascar, India, Antarctica, Australia, New Zealand and New Guinea.
Continental margin: zone between the ocean basin of the continent
Continental shelf: area underwater from the shore to the continental margin
Pangaea split into 2 around 150 million years ago

Position of mid-ocean ridges
Mid ocean ridge forms due to sea floor spreading, in which the rocks become older the further one moves away from ridge  volcanic activity occurs
Magma wells to the surface and solidifies, producing new ocean crust
Australia and Antarctica
South America and Africa
Iron materials in rocks line up according to the magnetic field of the Earth why they form. As lava coos, the rocks that form them retain what is called residual magnetism. When comparing data on magnetic fields in rocks on the ocean floor, there was a line of ridges that extends through the ocean floor  mid-ocean ridges
Old crust destroyed at subduction zones

Spreading zones between continental plates
When the plates move apart, molten material from under the crust moves up to replace the separating crust, resulting in sea floor spreading.
Oceans and continents form plates which move over the asthenosphere
Plate tectonics: study of movement of crustal plates (6)

Fossils in common on Gondwanan continents, including Glossopteris and Gangamopteris flora, and marsupials
Fossil: trace or remains of past lie
Mature seeds of glossopteris are too big to be dispersed by wind across oceans

Similarities between present-day organisms on Gondwanan continents
Examples include the beech tree, Nothofagus and flightless

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