Earth’s Layers

S6E5.a. Compare and contrast the Earth’s crust, mantle, and core including temperature, density, and composition.

We Have 2 ways of Dividing We Have 2 ways of Dividing Earth’s Layers:Earth’s Layers:

Earth is divided into Earth is divided into 3 3 compositional layerscompositional layers::

1. Crust1. Crust

2. Mantle2. Mantle

3. Core3. Core

CRUSTCRUST:: •Location: outermost layerLocation: outermost layer•Temperature: 0°C to 1,000°CTemperature: 0°C to 1,000°C•Thickness: 5km to 100 kmThickness: 5km to 100 km•Composition:Composition:• OxygenOxygen• SiliconSilicon• AluminumAluminum

• Oceanic crustOceanic crust is is very thin & dense.very thin & dense. • Continental crustContinental crust is thick but less is thick but less dense.dense.

2 TYPES OF CRUST2 TYPES OF CRUST::

MANTLEMANTLE:: •Location: Location: belowbelow the crust. the crust. •Temperature: 1,000°C to 3,700°CTemperature: 1,000°C to 3,700°C•Thickness: 2,900 kmThickness: 2,900 km•Composition: Composition: • Contains most of Earth’s massContains most of Earth’s mass• Solid and molten rockSolid and molten rock

CORECORE::•Location: Earth’s centerLocation: Earth’s center•Temperature: 3,700°C - 7,000°CTemperature: 3,700°C - 7,000°C•Thickness: 3,500 kmThickness: 3,500 km•Composition: mostly iron, some Composition: mostly iron, some nickelnickel•Divided into 2 layers:Divided into 2 layers:• Outer Core Outer Core • Inner CoreInner Core

Earth is divided into Earth is divided into 5 5 physical layersphysical layers::

1. Lithosphere1. Lithosphere

2. Asthenosphere2. Asthenosphere

3. Mesosphere3. Mesosphere

4. Outer Core4. Outer Core

5. Inner Core5. Inner Core

LITHOSPHERELITHOSPHERE: : •This is the “crunchy” layer of the This is the “crunchy” layer of the Earth.Earth.•Location: crust and upper mantleLocation: crust and upper mantle•Thickness: 15-300 kilometersThickness: 15-300 kilometers•Lithosphere = tectonic platesLithosphere = tectonic plates

ASTHENOSPHEREASTHENOSPHERE: : •Location: the middle mantle, below Location: the middle mantle, below the lithospherethe lithosphere•Soft – can bend like plasticSoft – can bend like plastic•Lithosphere floats on this layer (like Lithosphere floats on this layer (like jello)jello)•Thickness: 250 kmThickness: 250 km

MESOSPHEREMESOSPHERE: :

•Location: the strong, lower part of Location: the strong, lower part of the mantlethe mantle

•Thickness: 2,550 kilometersThickness: 2,550 kilometers

Outer CoreOuter Core::

• Composition: liquid iron (with some liquid iron (with some nickel)nickel)• Thickness: 2,300 kmThickness: 2,300 km

Inner CoreInner Core::

•Composition: Composition: solidsolid iron and a little iron and a little nickel. nickel. •Thickness: 1,220 km thick.Thickness: 1,220 km thick.•Solid because of increased Solid because of increased pressure.pressure.

CRUST

MANTLE

OUTER CORE

INNER CORE

LithosphereAsthenosphere

Mesosphere

• Moving towards the center of the Moving towards the center of the earth:earth:

•Density Density increasesincreases•Pressure Pressure increasesincreases•Temperature Temperature increasesincreases

Density, Pressure, and Density, Pressure, and TemperatureTemperature

•Earthquakes emit different kinds of Earthquakes emit different kinds of seismic waves that can travel seismic waves that can travel through different substances and at through different substances and at different speedsdifferent speeds

•Scientists used these waves to Scientists used these waves to determine the layers based on the determine the layers based on the speed and movement of the speed and movement of the layers!layers!

How do we know there are How do we know there are layers of the earth?layers of the earth?

•The Moho is the boundary where The Moho is the boundary where the crust meets the mantlethe crust meets the mantle

•It was discovered in 1909 by It was discovered in 1909 by Andrija MohorovicicAndrija Mohorovicic

•It was discovered because at this It was discovered because at this point density changes and seismic point density changes and seismic waves change directionwaves change direction

The MOHOThe MOHO

The MOHOThe MOHO

Why does Earth have a Why does Earth have a magnetic field?magnetic field?

Why does Earth have a Why does Earth have a magnetic field?magnetic field?

•Earth’s magnetic field is a result of the movement of iron in the Earth’s liquid inner core.

In Review:

1. What are the 3 main layers of the Earth?

Crust, Mantle, Core

2. Which layer is the least dense?

Crust

3. Which core layer is solid iron and nickel?

Inner core

4. What is the name given to the “crunchy” layer of the crust and uppermost part of the mantle?

Lithosphere

5. The motion in this layer is the reason Earth has a magnetic field.

Outer core