Tectonic Plates
The theory of tectonic plates is a geological theory which tells of the motions in large scale of the lithosphere of the earth. This theory of tectonic plates supersedes the continental drift theory of earlier times and also the seafloor spreading concept of 1960.
The earth’s interior’s outermost part is lithosphere. It has crust in the inner part and the outermost part is the mantle. The asthenosphere lies below the lithosphere. The asthenosphere can flow and is viscous in nature. The lithosphere is made up of tectonic plates and there are seven minor and major plates. The plates move one against the other in collision or convergent boundaries, spreading or divergent boundaries and boundaries that are referred to as transform. The different activities like oceanic trench forming, mountain building, volcanic activity, earthquakes are formed along the boundaries of tectonic plates.
Tectonic plates carry oceanic crust and continental crust. The African plate can include the Atlantic Oceans floor and the continental parts. The continental crust and the oceanic crust is different from each other in their degree of denseness. The Continental Crust is less dense than Oceanic Crust. The Oceanic Crust has heavier elements. That’s the reason why, the oceanic crust lies below the level of the sea, while the continental crust rises above the level of the sea.
