The CrustThe Crust

• SOLID layer of rock that forms Earth’s outer skin, including the solid earth and oceans.

• CONTINENTAL CRUST composed of granitic rocks, which are less dense than basaltic rocks of the oceanic crust. So, most of continental crust is above sea level.

• OCEANIC CRUST - composed of basaltic rocks, which are more dense than granitic rocks of the continental crust. So, oceanic crust is below sea level.

The Crust (CONTINUED)The Crust (CONTINUED)

• Composition:Composition: mostly oxygen, silicon, aluminum (Granite and Basalt)

• Temperature:Temperature: Varies from air temperature to 870 Co

(1600⁰ F)

• Thickness: 35 - 70 km (3 miles – 25 miles)

LithosphereLithosphere• Upper part of the mantle and the crust.

• Floats on top of the soft rock below it.

• Litho means “stone” in Greek.

• The crust and upper part of the mantle are very similar, so they are combined in this layer.

The MantleThe Mantle

• SOLID layer of hot rock between the crust and core.

Mantle (continued)Mantle (continued)

CompositionComposition: Solid rock, mostly iron and

magnesium

TemperatureTemperature: (16,000⁰ - 4000⁰ F)

Thickness: 2900 km (1800 mi)

(contains most of earth’s mass)Convection currents - hot

material in the mantle rises, cools and then

sinks.

Asthenosphere Asthenosphere

• Upper part of the Mantle.

• Molten (melted) rock layer.

• About 175 km thick.

The CoreThe Core

Center of the Earth;under extreme pressure

The Outer CoreThe Outer Core

Composition:Composition: LIQUID iron and nickel

Relative TemperatureRelative Temperature: 3,700oC – 4,300oC

(4000o – 9,000o F)

Thickness: 2,200km (1400 miles)

The Inner CoreThe Inner Core

Composition:Composition: SOLID iron and nickel

TemperatureTemperature: 7,200oC (13,000o F)

Thickness: 5,200km – 6,428km

The inner core is very hot, pressure from the weight of the rest of the Earth doesn’t allow the material to melt.

Iron’s normal temperature of melting is 15350C, but in the earth inner core it could stand 40000C with no melting.

Pressure equals 45,000,000 pounds per square inch.