Earth’s Layers

SC Standard 8-3.1 Summarize the 3 layers of Earth on the basis of relative

position , density and composition.

Earth is divided into Earth is divided into 3 3 basic layersbasic layers::

1. Crust1. Crust

2. Mantle2. Mantle

3. Core3. Core

These layers are then These layers are then subdivided into smaller layers.subdivided into smaller layers.

CRUSTCRUST:: •Is the Is the outermost layeroutermost layer on the earth. on the earth. (EGG SHELL)(EGG SHELL)

•Thickness variesThickness varies. Under mountains it . Under mountains it can be as thick as 60 km and less than 5 can be as thick as 60 km and less than 5 km under the ocean.km under the ocean.

•It is the It is the least denseleast dense of all the layers. of all the layers. (lightest layer)(lightest layer)

•It is made up of It is made up of siliconsilicon and and oxygenoxygen..

• Oceanic crustOceanic crust is is very dense, made of very dense, made of Basalt.Basalt. • Continental crustContinental crust is less dense, made is less dense, made of of Granite.Granite.

2 TYPES OF CRUST2 TYPES OF CRUST::

BASALTGRANITE

MANTLEMANTLE:: • Located Located belowbelow the crust. the crust. (Egg White)(Egg White)

• It is the It is the largest layerlargest layer (about 2900 km (about 2900 km thick). Rock layers are movable. thick). Rock layers are movable. (plastic)(plastic)

• Hot soften rocks made up of more Hot soften rocks made up of more magnesiummagnesium and and ironiron..

• Density increasesDensity increases with depth due to with depth due to increase in pressure.increase in pressure.

MANTLEMANTLE: : Divided into 2 partsDivided into 2 parts

• Upper mantleUpper mantle • Lower mantleLower mantle..

• Contains the “Moho” Contains the “Moho” (Mohorovicic (Mohorovicic discontinunity)discontinunity)

CORECORE: : (Egg Yolk)(Egg Yolk)• Located below the Mantle.Located below the Mantle.

• It is divided into 2 layersIt is divided into 2 layersOuter CoreOuter Core

Inner CoreInner Core

Outer CoreOuter Core::

• is is liquidliquid and is made up of mostly and is made up of mostly ironiron (easily magnetized)(easily magnetized)

• The movement of materials in the The movement of materials in the liquid O.C. is liquid O.C. is inferredinferred to be the cause to be the cause of Earth’s of Earth’s magnetic fieldmagnetic field!! (highlight in your (highlight in your notes)notes)

• The O.C. is about 2250 km thick.The O.C. is about 2250 km thick.

Inner CoreInner Core::

• Is the Is the centercenter of the Earth – 1200 km of the Earth – 1200 km thick.thick.

• It’s It’s solidsolid iron and nickel. Most dense iron and nickel. Most dense layer (heaviest) layer (heaviest) (highlight in notes)(highlight in notes)

• The increased pressure causes The increased pressure causes the I.C. to be solidthe I.C. to be solid

In your notes lets draw together a diagram of the Earth.

CRUST

MANTLE

OUTER CORE

INNER CORE

Look at the sub-layers of the mantle

LITHOSPHERELITHOSPHERE: :

• This is the “crunchy” layer of the Earth.This is the “crunchy” layer of the Earth.

• It includes the It includes the crustcrust and the very and the very uppermost part of the upper Mantleuppermost part of the upper Mantle

ASTHENOSPHEREASTHENOSPHERE: :

• Soft – can bend like plastic, layer in the Soft – can bend like plastic, layer in the upper portion of the mantleupper portion of the mantle

• It is located right below the Lithosphere.It is located right below the Lithosphere.Lithosphere floats on this layer (like jello)Lithosphere floats on this layer (like jello)

CRUST

MANTLE

OUTER CORE

INNER CORE

Lithosphere

Asthenosphere

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