Earth scientists have put forward the view that the Earth’s crust or the lithosphere is not a continuous block. It consists of several large and small, rigid, irregularly shaped plates (slabs) which include continents and the ocean floor. These slabs are moving or drifting in relation to each other by about 2.5 cm to 5 cm each year. These crustal slabs are called tectonic or lithospheric plates. According to the ‘Theory of Plate Tectonics’ put forward by the Earth scientists, the earth’s crust has been formed out of seven major and some minor tectonic plates or lithospheric plates.
