What is Plate Tectonics
‘Plate tectonics’ refers to the theory that talks about the drift of the earth’s lithosphere. The theory of plate tectonics goes well with the theory of continental drift. As per plate tectonics, the lithosphere is divided into seven or eight major tectonic plates. It is the movement of these plates that leads to the natural calamities like volcanoes and earthquakes. The movement of the plates takes place on the asthenosphere. There are mainly two types of lithospheric plates as per plate tectonics. The lithospheric plate on the ocean floor is thin and the continental plate is thick. The plates are under constant motion and the annual rate of movement is said to be approximately equal to a maximum of 100 mm annually.
The lighter nature of the lithosphere makes it able to move easily on the asthenosphere. Since the plates either push against each other or move away from each other, the total area under the plates is maintained constant. In convergent boundaries, faults are formed whereas the divergent floors are seen in places like ocean floors where the phenomenon of sea floor spreading is found. Plate tectonics explains almost all the phenomenon that happens with relation to formation ofyoung fold mountains, the increase in their height every year and formation of mountains under the sea bed.
There are seven major plates and seven minor plates. The formation of continents from one large continent due to the breaking of the large mass of earth is explained as per plate tectonics. Though there was opposition expressed to this theory in the beginning, the evidences that were found later, led to acceptance of the theory of plate tectonics. The shape of the present day continents seem to be an exact fit into one another when compared carefully with the help of imaging. Thus, this can be said to be the strongest evidence in support of the plate tectonics.
The remote sensing satellites too show the motion of the plates that takes place at a slow pace. Though the movement of the plates is said to be the cause for the formation of Fold Mountains and sea floor spreading, there is debate about the exact reason for the motion of plates. At present, the most widely accepted explanation is that the motion occurs due to the relative density of lithosphere and the asthenosphere. However, there are other explanations too that are provided by some scholars for the movement of plates, thereby, leaving the field open for debate.