Continental Plates | Universe Today

Written by Jerry Coffey

The size, shape, and land mass of the Earth has been determined over the millenia by the movement and drifting of the continental plates. This concept is based on plate tectonics and usually expressed as continental drift. The land mass of Earth started out as one massive supercontinent called Pangea. Slowly, at the rate of a few centimeters per year, the continents moved to their current positions. That doesn't mean that they are going to stay in place forever. The plates continue to shift, collide, and in general wreak havoc on our planet.

The Earth has several continental plates and oceanic plates. These plates are from 80 to 400 km thick. The names of these plates are: the Eurasian plate, Australian-Indian plate, Philippine plate, Pacific plate, Juan de Fuca plate, Nazca plate, Cocos plate, North American plate, Caribbean plate, South American plate, African plate, Arabian plate, the Antarctic plate, and the Scotia plate. These plates have been broken down into smaller sub-plates. These plates are in constant motion, often colliding and reforming the Earth's geography. The continental plats move in any of three ways: divergence, convergence, and lateral slipping.

Different things happen when the continental plates move in different ways and the results of their interactions differ because of this. Divergence happens when two plates move away from each other. This usually causes the seafloor to spread. Convergence is when two plates collide. Some of the Earth's crust is destroyed, but the end results depend on the type of plates involved. When a thin, dense oceanic plate collides with a relatively light, thick continental plate, the oceanic plate is forced under the continental plate; this phenomenon is called subduction. When two oceanic plates collide, one may be pushed under the other and magma from the mantle rises, forming volcanoes in the vicinity. When two continental plates collide, mountain ranges are created as the colliding crust is compressed and pushed upwards. Lateral slipping happens when two plates move sideways against each other, there is a tremendous amount of friction which makes the movement jerky. The plates slip, then stick as the friction and pressure build up to incredible levels. When the pressure is released suddenly, and the plates suddenly jerk apart, this is an earthquake.

There are many things that can be said about the continental plates, but most of them lead back to plate tectonics. There is a good article about plate tectonics here. Here on Universe Today we have a couple of great articles related to the continental plates: one about convergent boundaries and another about subduction. Astronomy Cast offers a good episode about plate tectonics.

Filed under: Astronomy