Plate Tectonics (Structure of Earth)
Table of Contents
The global movement of crustal blocks is referred to as plate tectonics. Plates are constantly moving around the globe a few centimetres a year. Eventually when they collide or diverge they usually leave a trail of enormous destruction.
Alfred Wegener was the first person to conduct the theory of continental.In his studies he implied that continents where once joined together in a supercontinent known as Pangea. Eventually the supercontinent splitted into the northern part(Laurasia) and southern part(Gondwanaland). The continents continued splitting into the continents we known today.
Structure of Earth
Crust-The crust is the first, very thin layer. It consists of the oceanic and the continental crust.It ranges from 5-40km in thickness. Continental Crust or Sial is thick than the oceanic crust but its materials are light and therefore bouyant. The Oceanic Crust or Sima is the crust situated along oceans and is thinner than the continental crust.Oceanic crust are dense and because of their density they sink below the less dense continental crust.
LithosphereThe crust and the upper rigid layer of the mantle form the lithosphere(plate).
Lower MantleThe lower mantle which consist the asthenosphere is a zone of weak rocks where intense convectional currents occur.It is because of these currents which causes the plates(lithosphere) to float on the surface.
CoreThe outer core consist of molten rocks while the inner core is solid and rich in iron.