E ARTH ’ S I NTERIOR

S TUDYING B ELOW E ARTH ’ S S URFACE The extreme conditions of Earth’s interior make it very hard to study the inside of Earth. We must.. Study rock samples from inside Earth. Study seismic waves from earthquakes and how they travel through different parts of Earth.

Seismic wave-a wave of energy that travels through Earth after an earthquake.

D IGGING DEEP … The deeper in Earth you get, the hotter the temperature becomes. Pressure also increases greatly the deeper you get. Pressure is the amount of force on an area. Density also increases the deeper you get, due to the pressure.

E ARTH ’ S C OMPOSITIONAL L AYERS Earth’s compositional layers are determined by density differences.

C RUST The outermost layer of solid rock including dry land and the ocean floor. Thickest under mountains, thinnest in the oceans. Oceanic crust-darker in color and made of basalt. Continental (land) crust-lighter in color and made of granite.

M ANTEL Made up of rock that is very hot, but solid. (3,000 kilometers thick). The rock in the mantel is soft and flows slowly but is still considered solid. (if you kicked the mantel it would hurt your foot). Convection-the movement of rock because of differences in density due to temperature. Hotter rock rises, colder rock sinks.

C ORE Center of Earth Made of iron and nickel

P HYSICAL L AYERS Based on whether the layer is solid or liquid.

L ITHOSPHERE Includes the crust and uppermost mantel. Stiff and rigid. Divided into tectonic plates.

A STHENOSPHERE Soft layer beneath the lithosphere which is more flexible and can bend. Tectonic plates float on asthenosphere.

M ESOSPHERE Strong, lower part of the mantel. Denser than the asthenosphere and therefore more solid.

O UTER C ORE Liquid layer that surrounds the inner core.

I NNER C ORE Dense, solid metal. High pressure causes the metal to be solid.

E ARTH ’ S M AGNETIC F IELD Movements in Earth’s liquid core create a magnetic field. Planet Earth acts as a giant magnet.