Earth's Interior

Earth's Interior

Divided into two layers based on geochemical composition.

Minerals

Naturally occurring crystalline solids with defined chemical compositions.

Crystalline Solid

Material whose atoms are arranged in a fixed and repeated pattern.

Rocks

Aggregates of one or more minerals stuck together by weak chemical bonds.

Average Igneous Rock Composition

Geologists approximate the compositions of the Earth using this.

Rheology

The study of how materials change in size, shape, or position when under stress.

Brittle Deformation

Material breaks under stress.

Elastic Deformation

Material temporarily changes shape but returns to original configuration after stress is removed.

Ductile/Plastic Deformation

Material flows or changes shape permanently but does not break.

Pressure Gradient

Pressure experienced in Earth is due to the weight of overlying rocks.

Higher Density, Higher Pressure

The relationship between density and pressure in Earth's interior.

Temperature Gradient

Temperature increases with depth in the Earth.

Seismology

The study of earthquakes, the seismic waves they produce, and how those waves propagate through the planet.

Earthquakes

Occur when faults move and rocks fracture, producing waves of traveling energy.

P-Waves

Compressional waves where materials move parallel to propagation direction; can propagate through solids, liquids, and gases.

P-Waves Bending

P-Waves bend when they enter a new material.

Shadow Zone

Area where there are no P-Waves between 103-150 degrees.

S-Waves

Shear waves where material moves perpendicular to propagation direction; can only propagate through solids.

Seismogram

Tool that measures seismic waves.