Theory of Continental Drift
The lithosphere is divided into seven large and several small plated. The rigid plates float on the underlying semi-molten mantle and are moved by convection currents - proposed by Wegner in early 20th century.
The plates moving creates convergentadn divergent plate boundaries where the plates are destroyed and created at an equal rate. Transform boundaries are where two plated move alongside one another.
...created by radioactive decay in the mantle and core which is heated by the core. When the particles in the lower atmosphere heat up, they become less dense and rise.
As they move to the top of the Asthenosphere and lithosphere, it cools down, becomes denser and starts to sink in a ciruclar movement - this causes the plates to move.
- Due to its relatively low density, continental crust does not sink and so is permanent: being denser, oceanic crust can sink. Oceanic crust is being formed and destroyed continuously
- Continental plates like the Eurasian Plate may consist of both continental adn oceanic crust
- Continental crust can extend beyonf the land mass