Convection Currents: the movement of matter due to differences n density that are caused by temperature variations; can result in the transfer of energy as heat.
Oceanic Crust: the part of the earth's crust that is below the ocean. The rock that makes up the oceanic crust is about 200 million years old.
Continental Crust: a layer of igneous, sedimentary as well as metamorphic rocks. This layer structures the continents and the regions of shallow seabed close to their shores which are called continental shelves.