Theory of Plate Tectonics is a theory which describes the large scale motions of Earth's lithosphere. It is vital for the existence of life on earth because of the role that it plays in the global cycle that maintains the balance of carbon between the biosphere, geosphere, hydrosphere, and atmosphere.
It is the theory that the top crust of the world is actually a series of plates that are floating on the magma beneath these plates are constantly crowning and changing and where the plates meet is where you usually find the most active volcanic and earthquake activity. This is due to one plate being forced under the other plate where they are eventually returned to the magma or pushed up into mountains and new volcano's The stronger plate Will have the volcano's and the friction and heat generated from the collision is built up as retained energy that is released by either a volcanic eruptions or earthquake.
The theory of plate tectonics was developed due to the mid-oceanic ridge seismic activity. The seismic activity in that region allows for the implication of plates of dense granite rock to float over a layer of magma just beneath the earth's crust and on top of the earth's upper mantle.
According to theory of plate tectonics; the outer most layer of earth which is known as lithosphere consists of various single segment; knows as plates. Up till now almost 20 plates are discovered.
The largest plate which is discovered up till now is Pacific plate. It is also an important fact that all other plates contain both continental and oceanic crust, whereas most of the smaller plates consist of oceanic material. After lithosphere there is another zone known as Asthenosphere .it consists of weaker and hotter material. In the ocean plates are normally thinnest and it varies from almost 50 to 100 kilometers .
whereas reverse happened in the case of continental plates .continental plates are normally thicker and in some area the thickness exceed 150 kilometers. One of the main aspects of plate tectonic theory is that each plate is in motion with relation to other plate. As the plates moves, the distance between the 2 cities which are on the same plate will remain constant but the countries which are on located on the different plates their distance will change constantly. So, all the major activities like earthquake, volcanisms and mountain building all of them are related to plate tectonic theory.
From a world map of the mid-ocean ridges and the consumption boundaries, geologists have divided up the whole earth's surface into six large (and several smaller) plates of rigid rock. These plates, they postulate, are being formed at the ridges and move like a conveyor belt toward boundaries with other plates, where one of them is thrust underneath into the mantle and is dissolved. The continents are carried on these plates, like an Eskimo's igloo on an ice floe.
This is called the tectonic-plate theory, from the Greek word for "builder." Both the continental drift and the sea-floor spreading are included as parts of the broader theory.
The American plate, which carries both North and South America, as well as the western half of the Atlantic Ocean, theoretically is being formed at the mid-Atlantic ridge and moving west. Along the western coast of South America, a smaller plate arising in the eastern Pacific collides with and plunges under the American plate. This supposedly causes a deep trench in the ocean off the coast of South America, and lifts the Andes mountains to the highest peaks in the Americas. The crumpling of the oceanic plate causes frequent earthquakes all along the Pacific coast. When, according to the theory, the lighter rock carried down into the mantle melts, it rises through cracks in the continental crust above it to form the volcanoes in the Andean Cordillera.
