Lets begin plate tectonic with an easy introduction ,We all know that Earth revolves around Sun as all the planets in our solar system but the hidden fact is that there is also a movement within the spheres of earth crust with the help of the force that is generated within and inside from the Earth’s core.
Like a cabbage which is made up of layers of leaves, in the same way our planet Earth is also made up of, and is also surrounded from its inside with the layers called Crust, Core and Mantle where crust is divided into two layers, Continental Crust and Oceanic crust which is commonly called as lithosphere where in Oceanic crust is more denser and strengthen than the continental crust which makes Continental crust to flow above the asthenosphere layer which is present in Mantle.
PLATE TECTONIC THEORY PROPOSED BY WEGENER
The continents that we see in the present world were separated from a huge land mass because of their drifting this has been proposed by Alfred wegener in 1912, who noticed that all the continents seem to be fit together like a Puzzle, for example, the west African coastline seems to be a nice fit when we get into the east coast of South America and the Caribbean Sea and also a similar of it has been observed across the Pacific. It is even more striking when the submerged continental shelves are compared rather than the coastlines. This has been observed that all these has separated because of their lifting from a huge landmass called Pangaea and formed into seven big Continental plates and several small minor Continental plates but he haven’t explained the reason of their drifting but he only explained that these drifting has separated continents of present day from a landmass called Pangaea. Drift hypothesis also provided an alternative explanation for the formation of mountains through orogenesis
PLATE TECTONICS PUT FORWARD
But in 1929, about the time Wegener’s ideas began to be dismissed,Arthur Holmes elaborated on one of the Wegener’s many hypothesis ,the Idea that mantle undergoes thermal convection. Now, plate is a large digit slab of solid rock the word tectonics comes from the Greek word to build so putting these words together and spelling it as plate tectonics refers to how the Earth surface is built of plates and here the theory of plate tectonics proposed states that its outermost layer is fragmented into a dozen or more number of small plates that is moving relative to one another and mobile always above the hot molten material present in Mantle.
CONTINENTAL DRIFT THEORY VS PLATE TECTONICS
Continental drift theory explains that the supercontinent Pangaea has begun to break from about 225 to 200 million years ago and it eventually got fragmented into a present day world and it also explains about the formation of volcanoes, earthquakes and eruptions but the plate tectonics in a scientific way relatively explained why this drifting has happened and why we say that quakes and volcanic eruptions has occurred in a very specific areas around the world and why great mountain ranges the Alps and Himalayas were formed.
PLATE MOVEMENTS, plate tectonic theory summary
Now let us look into the fact that how these plates move each other there are three kinds of moments where in the plates move relatively they are 1)Transform,2) Divergent and 3)Convergent.
Transform movement is a kind of moment where the plates move parallel without subducting each other and this movement might be in the same direction of both the plates or in opposite direction to each other.
In the divergent movements, the plates move apart from each other by making a space for the molten lava underneath the Mantle to come out and form a new surface. So in the divergent movement we can say that new area has been formed with this molten lava coming up and cooling down there is also a possibility of forming a small bow shaped mountain area in these areas of divergent plates.
It is generally believed that these divergent happens mainly in the sea which is described as seafloor spreading which tells about the divergent zones and the coming up of molten lava and forming the area happens mainly in the sea which make the sea spread apart and further leads to the movement of the plates, that way the Oceanic crust movie part, this mainly happens in the region of Atlantic ocean which further makes North America, South America and Europe, Africa move apart each other.
And next come the convergence zone or it is also called a subduction zone, with one plate subducts or pushes the other plate underneath and hence the molten lava to increase more and more and it will also help the other part of the divergent zone to make it a new surface so the plate which goes under need the other place to rise itself.
CYCLES IN PLATE MOVEMENTS
Here we can say that the Lava that rises up in that divergent zone is a resultant of the place that is itself melted in a conduction zone so there is an equal balance between the divergent and convergent zone which is called conveyor belt principle .
Due to some pressure from the inner core of earth volcanic eruptions happen in these which after extinction remind bow shaped hills or peaks. As we have already seen, the opening and closing of the divergent and convergent plate where it collides and separates one another of ocean basis is the Wilson cycle and it is a simplest model we have of how the Earth operates historycally and itself.
Volcanism and earthquakes and highlands of Mountain buildings arose when large pieces of material on the subduction zone collide and contract each other in the overriding plates and subject to earthquakes. Most of the boundaries between these individual plate of divergent and convergent of subduction zone cannot be seen and most of them are under the oceans and it can be seen from the outer space by measurements from GEOSAT satellites. Earthquake and volcanic activities can also be concentrated. So this is the process of wonderful mechanism and process of plates drifting which might also leads to the formation of new land masses and also disappearance of the small minor plates which were present from the past days.