Plate tectonics under the earth's surface shift to cause the continents to move and many different environmental features to form. the earth changed a great deal throughout the years. Around 250 million years ago the continents formed a supercontinent called Pangea.
This supercontinent allowed for the distribution of different animals and plants on different continents. Pangea is the reason that people find fossils of a certain type of species on Africa and also on South America; at one point, these continents touched.
Pangea began to break up around 150 million years ago. the continents began their drift to the position that they are in today. this took millions of years. When dinosaurs existed on earth (around 66 million years ago), the planet looked like this:
The continents are not done moving. In millions of years they will look much different than they do now. It is estimated that the continents will look like the following picture when 250 million years has passed. It is believed that another supercontinent will form.
If you would like to know more about the movement of the continents over the years you should visit http://www.scotese.com/earth.htm.
Saying that continents are moving at a rate of only 2 cm per year as an umbrella is not correct. There are about 16 to 20 plates on earths surface, and we do not know the exact number because it is believe that some of the plats are made up of micro-plates. Also 'continental drifting' has been discovered to be false, as there are mechanisms behind the movements of these plates, as they are more or less pulling, pushing and sliding up against one another. These plates are not just drifting over the Asthenosphere.
ReplyDeleteI like the use of the successive pictures. I think they bring a nice visual element to the post.
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