what are tectonic plates and what do they do
Tectonic plates are segments of the Earth's lithosphere, the hard rocky outer shell composed of the crust and the uppermost mantle. This shell is divided by lines of faults, ridges of plate creation, and zones of plate destruction. The plates are composed of crustal rock and solid upper mantle which is called the lithosphere. * 2  Plates are composed of continental and oceanic crust. 3  The oceanic crusts are continually moving, spreading from the center, sinking at the edges, in a process of recycling.