|
Laurasia was composed of Europe, North America and Asia, while Gondwana was composed of Africa, South America, New Zealand, Madagascar, India, Antarctica, Arabia, Iran and Australia.
There is supporting evidence in favour of the theory of continental drift. This includes similarities in rock types, fossils, flora and fauna of the continents. An example of this is the Indian continent, which is considered a "southern land mass" and is often referred to as "the sub-continent". India broke away from Antarctica and Africa about 100 million years ago, yet the living flora is more closely related to the flora of Africa than that of Asia. This is because India is pushing into Asia (hence the Himalayas which are still rising to this day) and is not actually a part of Asia.
As well as the living flora today, there is ample supporting evidence of this theory in the fossil record. The presence of the order Glossopterid in the fossil records of Australia, Antarctica, India, Africa and South America suggest that these continents were joined at one time. Glossopterid fossils have never been found in Asia. There are other fossil species shared across the southern land masses including Deucridium spp, and a range of reptiles, amphibia and fish.
HOW DO THE CONTINENTS MOVE?
The earth's crust consists of at least fifteen plates. These are made of rigid lithosphere, and carry the world's continents. When these plates clash, they can cause earthquakes and volcanoes to erupt, as new earth rises to the surface.
One of the reasons why there are no earthquakes or live volcanoes in Australia is because Australia lies in the middle of the Indian-Australian plate. Countries or regions that lie on the areas where the plates meet are often subjected to these phenomena, examples being New Zealand which has lots of volcanoes due to its location on the Indian-Australian and Pacific Plates, and the west coast of the United States, which lies on the join of the Pacific and American plates.
While the plates are moving, the continents are drifting also.
India is pushing so hard into Asia, that it is being forced underneath the Asian continent, and hence the height of the Himalayas is rising every year! Australia is also moving north, albeit at a much slower 6cm a year. In the last 45 million years, Australia has moved through 27° of latitude. In another 20 million years, Cape York will have reached the equator!
This website has a series of maps showing continental drift -
click here to view
maps.
|
