Plate Tectonics...!

What has happened at least once, it can happen again. And happen. The movement of the plates that form the Earth's crust sliding on a film, subject to strong tensions, can not stop.

Why do not you noticed? Well, it's a very slow movement, or our vision very quickly. But the continental drift is unstoppable, as is the exit to the outside of new materials in the ocean ridges and sinking in subduction zones.

Recall that the continents are just some of the land emerged plates and, certainly in the future will change shape and position many times, as they did in the past.


PANGEA!!

Before the drift of Pangea is known that there had been previous periods of drift. Pangea had lasted only a few hundred million years and was originally formed from the union of a set of different land masses of present continents, which were in turn fragments of another supercontinente. It appears that the fracture, dispersion and meeting supercontinentes is an ongoing process.

In fact, they are not continents, but the actual ocean floor that moves and thus dragging the continents. The process continues, his and continents continue to drift, usually because of a few centimeters a year. Therefore, the current provision is not permanent.

The Atlantic Ocean is widening as Africa and America are separated, while the Pacific Ocean is being dwarfed. It also narrows the Mediterranean Sea, and ultimately disappear, because Africa is moving northward, to meet Europe.


When Pangea split into Laurasia and Gondwana, India was part of Gondwana. Later he broke and moved quickly northward to the unusually high speed of 17 cm per year, until colliding with Asia and to unite the continent. The pressure in India against Asia caused the folding of the crust and the formation of the Himalayas, a phenomenon that still continues.

It is believed that the union or suturing of land masses will be repeated again and again in the future and that all continents will meet again in a supercontinente.

Theory....

According to the theory of plate tectonics, the earth's crust is composed of at least a dozen rigid plates that move on their own. These blocks are resting on a layer of hot rock and flexible, call asthenosphere, which flows slowly like hot tar.

Geologists have not yet determined exactly as they interact with these two layers, but the most cutting-edge theories argue that the movement of the molten material thick and the asthenosphere to force the plates to move higher, sink or rise.

The basic concept of the theory of plate tectonics is simple: heat rises. The hot air rises above the cold air and warm water currents float above the cold water. The same principle applies to the hot rocks under the earth's surface: the melt of the asthenosphere, or magma, rising upward, while the cold and hardened area is sinking more and more towards the fund, within the mantle. The rock is sinking finally reaches the high temperatures of the lower asthenosphere, is heated and begins to climb again.

This continuous movement and, somewhat circular, is called convection. At the edges of the plate and in different areas of the lithosphere solid hot, molten material flows to the surface, forming new crust.

Here is a videoo!!

http://video.google.com/videosearch?q=plate+tectonics&hl=en&emb=0&aq=0&oq=plate+t#