The Layers of the The Layers of the Earth!Earth!

Earth LayersEarth Layers

• The Earth is divided into three major zones that are defined by their compositions.

*Core (Inner and Outer)*Mantle *Crust

The CrustThe Crust*The Earth’s crust is the

thin, rocky outer layer of Earth

*It is composed of the oceanic and continental crust

*The crust makes up 1%

of the Earth.

* The crust of the Earth is broken into many pieces called plates.

CrustCrust

• Oceanic crust is composed of basalt

• Continental crust is composed of granite

• Temp of crust - up to 870◦C

• Approx. 30 miles deep

The MantleThe Mantle

*. The mantle is the layer below the crust

*The mantle is the largest layer of the Earth; over 82% of the Earth’s volume

*The mantle is divided into two regions: the upper and lower sections.

MantleMantle

• 1,800 miles thick

• Temp – up to 2700◦ C

• Composed of dense rock and semisolid rock

Outer CoreOuter Core* The core of the Earth is

like a ball of very hot metals; it is composed of an iron-nickel alloy.

* The outer core is liquid.

* The flow of metallic iron within this zone generates the Earth’s magnetic field.

Inner CoreInner Core

The inner core of the Earth is compressed into a solid state by the immense pressure.

• The inner core is a solid.

• Temp - 7200◦C

• Depth of up to 2100 mi

LithosphereLithosphere

*The rigid outer layer of Earth, including the crust and upper mantle.

AsthenosphereAsthenosphere

Is the hotter upper mantle below the lithospheric plate;Can flow like silly putty; andIs a viscoelastic solid, NOT liquid!!

Seismic WavesSeismic Waves*Seismic waves are the vibrations fromearthquakes that travel through the Earth.

*They are the waves of energy suddenly created by the breaking up of rock within the earth or an explosion .They are theenergy that travels through the earth and is recorded on seismographs.

Types of Seismic WavesTypes of Seismic Waves

• Surface Waves

• Body WavesP wavesS waves

Surface Waves* Seismic waves that travel along the Earth’s outer layer.

* They travel along the ground and cause the ground and anything resting upon it to move.

*Surface waves are the most destructive *Surface waves are the most destructive earthquake waves.earthquake waves.

Primary or p-wavePrimary or p-wave

* The first kind of body wave is the P wave or primary wave. This is the fastest kind of seismic wave. The P wave can move through solid rock and fluids, like water or the liquid layers of the earth. It pushes and pulls the rock it moves through just like sound waves push and pull the air.

* Compression wave

Secondary or s-wave Secondary or s-wave * Transverse wave

The second type of body wave is the S wave or secondary wave, which is the second wave you feel in an earthquake. An S wave is slower than a P wave and can only move through solid rock. This wave moves rock up and down, or side-to-side.

ReviewReview1) What are the three layers of the Earth?

2) The Earth’s crust is very ______?

3) The mantle is the largest layer of the Earth? True or False

4) Is the Outer Core a liquid or a solid?

5) What is the difference between p-waves and s-waves?

6) What are surface waves?

Answers!Answers!

1) Crust, Mantle, Outer Core, Inner Core2) Thin3) True4) Liquid5) P waves are primary waves and S

waves are secondary waves6) Waves that occur on the Earth’s crust.

Cause the most earthquake damage.