Earth’s Interior and Plate Tectonics

CHAPTER 4

Earth’s Composition:

•Not just solid rock

•Distinct layers

•Each layer has certain physical properties

3 Main Layers3 Main Layers

►CrustCrust►MantleMantle

►CoreCore

CrustCrust►Outermost layerOutermost layer►5 – 100 km thick5 – 100 km thick►Thinnest layerThinnest layer►2 types of crust2 types of crust►< 1% of Earth’s mass< 1% of Earth’s mass

Continental CrustContinental Crust

►Average thickness Average thickness of 30 kmof 30 km

► Composition Composition similar to granitesimilar to granite

Oceanic CrustOceanic Crust►Average thickness Average thickness

from 5-8 kmfrom 5-8 km► Composition Composition similar to basaltsimilar to basalt

Oceanic crust Oceanic crust is is more densemore dense

than than Continental Continental

crustcrust

MantleMantle►Between crust and Between crust and corecore

►Extremely thick and Extremely thick and 67% of Earth’s mass67% of Earth’s mass

►Large amounts of Iron Large amounts of Iron and Magnesiumand Magnesium

The CoreThe Core

►33% of Earth’s 33% of Earth’s massmass

►2 separate 2 separate layerslayers

Outer CoreOuter Core

►Liquid layerLiquid layer

Inner CoreInner Core►Solid and denseSolid and dense►About 6,378 km About 6,378 km below the surfacebelow the surface

►6,000 6,000 ooCelcius (hotter Celcius (hotter than Sun’s surface)than Sun’s surface)

LithosphereLithosphere

►Made of the Crust Made of the Crust and Upper Mantleand Upper Mantle

►RigidRigid►About 150 km thickAbout 150 km thick

AsthenosphereAsthenosphere

►Part of the mantlePart of the mantle►Made of rock Made of rock (molten)(molten)

►Flows like putty Flows like putty (very viscous)(very viscous)

Lithosphere is Lithosphere is broken into broken into tectonic tectonic platesplates

Tectonic PlatesTectonic Plates

►Rigid, solid rockRigid, solid rock►Move around on Move around on AsthenosphereAsthenosphere

►Jigsaw puzzleJigsaw puzzle

Some plates Some plates contain both contain both continentalcontinental and and oceanicoceanic

crustcrust

How do we How do we know what the know what the Earth’s interior Earth’s interior

looks like?looks like?

Deepest hole Deepest hole drilled:drilled:

►12.2 km into the 12.2 km into the earthearth

►Kola Pennisula, Kola Pennisula, Russia 1984Russia 1984

Seismic WavesSeismic Waves►From earthquakesFrom earthquakes►Travel through Travel through earth layersearth layers

►Speed depends on Speed depends on density of materialdensity of material