Currents in the mantle move magma towards the surface. That is the sea floor. Where the sea floor, or oceanic crust expands new crust is continuously formed by magma and marine sediments. Thus oceans like Atlantic have a ridge in the middle. The mid-Atlantic ridge is infact the longest mountain range in the world and moves America away from Europe and Africa by about 2cm. 1inch a year.
Showing posts with label continental drift. Show all posts
Showing posts with label continental drift. Show all posts
Saturday, July 7, 2012
Subduction
Diving plates when oceanic and continental crusts crash, the softer and thinner oceanic crust bends downwards in what is called subduction, while the continental crust forms a range like the Andes and the rocky mountains. The subduction movements may cause deep earth quakes. The material of the oceanic crust melts and breaks down in the viscous mantle.
Subscribe to:
Posts (Atom)