Our planet’s geology is dominated by plate tectonics, in which crustal plates move slowly in response to mantle convection. The outer layer, or crust, consists primarily of oceanic basalt and continental granite.

Its interior composition and structure are probed using seismic waves. Such studies reveal that Earth has a metal core and a silicate mantle.

basalt — igneous rock produced by the cooling of lava; makes up most of Earth’s oceanic crust and is found on other planets that have experienced extensive volcanic activity. seismic wave — a vibration that travels through the interior of Earth or any other object; on Earth, these are generally caused by earthquakes. convection — movement caused within a gas or liquid by the tendency of hotter, and therefore less dense material, to rise and colder, denser material to sink under the influence of gravity…. magnetosphere — the region around a planet in which its intrinsic magnetic field dominates the interplanetary field carried by the solar wind; hence, the region within which charged particles….