The surface of the Earth is broken up into large plates. The Earth is dynamic because of its inner heat, which comes from deep in the mantle where heat, rising and falling inside it, creates convection currents generated by radioactive breakdown in the core. The convection currents move the plates. Where convection currents diverge near the Earth's crust, plates move apart. Where convection currents converge, plates move towards each other. The movement of the plates, and the activity inside the Earth is called plate tectonics. Plate tectonics cause earthquakes and volcanoes. The point where two plates meet is called a plate margin or boundary. Earthquakes and volcanoes are most likely to occur either on or near plate boundaries.
Francis Bacon was one of the first people to propose that the West Coast of Africa and Europe seem to have a jigsaw fit with the Eastern Seaboard of North and South America. But it wasn't until Wegener put forward his theory that plates moved, that great advances were made into understanding this element of our Earth. It is thought that in the past, Earth had one massive continent called Pangea, 300 million years ago, which has slowly drifted further and further apart.
The first piece of evidence to support Wegener's theory came from the discovery of the Mid-Atlantic Ridge. Vine and Matthews, who were British Geologists, discovered magnetic lines running parallel to the ridges in the 1960s. These lines corresponded to the times when the Earth's magnetic field reversed from South to North and so on. Iron particles in the erupting magma either side of the ridge cooled and aligned themselves with the Earth's polarity at that time. These lines supported a theory by Hess (a geophysicist) on sea floor spreading, which we know exists at the Ridge. Also, by studying...
English: Map showing the Mid-Atlantic Ridge splitt...
The Arabian tectonic plate is converging with the ...
Internationalization of the diagram Proeminent_hot...