Continental Drift

This Link like many others talks about a slow but normal process of new land being formed in the centers of oceans and moving toward the shores. My question is why? Does anyone know the mechanics behind how and why this works this way?

Offered by Mike.

Continental crust, mostly silica (quartz-like), has formed mainly from volcanic eruptions. The fact that the magma rises to the surface and spews out indicates that it is composed of lighter minerals. The continental crust is not easily subducted. So it stays around for millions of years longer than the oceanic crust, which is easily subducted. When 2 continental plates collide, they usually form huge mountains (like the Himalayas), instead of one subducting under another.

Of course, there are many sedimentary rocks also, which are exposed when a hot spot makes an entire section of oceanic sediment rise above sea level. (This in and of itself is catastrophic in nature). The mechanism of the current movement of these plates is so easily explained by a pole shift every so often. The plates are still in motion from the last time they were flung around, continuing with the existing momentum. The fact that things are speeding up also indicates that some new catalyst is in the mix, adding new momentum.

The oceanic crust is extruded at places like the oceanic rifts, below the ocean. First and foremost, this oceanic crust is composed of heavier and more brittle minerals than continental crust. I can speculate that it is thinner due to the weight of the ocean, and the fact that it spreads out under the push from the newly forming extruded crust, which in turn is the mechanism behind its subduction under the continental crust at the continental crust boundary. It is probably in the center due to being symmetrical. In other words, when the rift formed, the two continental plates were one, and over time, they spread apart about equally on either side of the rift.

Offered by Leila.