Earth’s Interior =mOSpRzW2i_4

Seismic waves are measured by seismometers The study of seismic waves (seismology) enables us to infer the composition of the earth.

The Four Layers The Earth is composed of four different layers. The crust is the layer that you live on, and it is the most widely studied and understood. The mantle is much hotter and has the ability to flow. The outer core and inner core are even hotter with pressures so great you would be squeezed into a ball smaller than a marble if you were able to go to the center of the Earth!

Earth’s Interior Within the Earth density, pressure, and temperature all increase with depth ESRT Page 10 Heat is created by the radioactive decay and primordial energy (left over from Big Bang)

The Crust The crust is composed of two rocks. The continental crust is mostly granite. The oceanic crust is basalt. Basalt is much denser than the granite. Because of this the less dense continents ride on the denser oceanic plates.

The Lithosphere The crust and the rigid outer shell of the mantle together make up a zone of rigid, brittle rock called the Lithosphere.

Moho discontinuity – the boundary between Earth’s crust and mantle –Seismic waves speed up here due to there being different material

Asthenosphere Part liquid, part solid layer of the mantle, referred to as the plastic mantle

The Mantle The Mantle is the largest layer of the Earth. The middle mantle is composed of very hot dense rock that flows like asphalt under a heavy weight. The movement of the middle mantle (asthenosphere) is the reason that the crustal plates of the Earth move.

The Outer Core Molten, Iron-rich, layer Is this a solid or liquid? Liquid layer Earth’s magnetic field is generated by convection in outer core

The Inner Core Solid, iron rich

Shadow Zones A zone on the opposite side of the earth from where an earthquake has occurred where no seismic waves are recorded. Due to the way that seismic waves travel through the different materials within the Earth. P and S waves get refracted (bent) when they hit different materials within the earth

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