The crust is the top and the thinnest, coldest, and most fragile layer of all 4. In different places, the crust may vary a lot in thickness. For example, under the oceans and Hawaii, it’s around 3 miles thick, and under the continents, it’s much thicker — from 18 to 43 miles.

The crust consists of several elements including oxygen, aluminum, silicon, calcium, iron, sodium, magnesium, and potassium.

The crust and the upper mantle layer are split into big pieces called tectonic plates. The plates are not immobile, they are moving 1.2 to 2 inches per year. Over time, the plates crush into each other, which cases most earthquakes and volcano eruptions.

There’s no clear answer as to what makes the plates move. Maybe it’s due to the heat-driven convection currents in the mantle below. Some experts think it’s caused by the tug from slabs of crust of different densities.

Comments to article «What Planet Earth Consists Of»