what’s inside the earth

What’s inside the Earth?What’s inside the Earth?Is there really another world Is there really another world at the center?at the center?

What is the What is the energy for surface energy for surface

features?features?

Our Dynamic Our Dynamic EarthEarth

Earth is constantly Earth is constantly changingchanging

How do we know it’s How do we know it’s dynamic??dynamic??

Earthquakes (and Earthquakes (and tsunamis)tsunamis)

Volcanic eruptionsVolcanic eruptions Surface Features:Surface Features:

– Mountain Ranges; Mid-Ocean Mountain Ranges; Mid-Ocean Ridges; Deep-Sea TrenchesRidges; Deep-Sea Trenches

Topography of the Ocean Topography of the Ocean FloorFloor

Mid

-Oce

an

Rid

ge

Topography of the Ocean Topography of the Ocean FloorFloor

Mid

-Oce

an

Rid

geDeep-sea

Trench

Topography of the Ocean Topography of the Ocean FloorFloor

Mid

-Oce

an

Rid

geDeep-sea

Trench

Topography of the Ocean Topography of the Ocean FloorFloor

IslandChain

Elevated Continents

Elevated Continents

Submerged Ocean Basins

Questions:How are the ocean basins formed?

How permanent are these features?

What is the age of the ocean floor?

What’s the age of the continents?

Why are the ocean basins deep and the continents high?

The Surface of the The Surface of the EarthEarth

2 levels:2 levels:– elevated elevated continentscontinents– submerged submerged ocean basinsocean basins

What causes these surface features?What causes these surface features? We must know what goes on We must know what goes on insideinside the the

EarthEarth

What’s going on inside What’s going on inside the Earth?the Earth?

Early IdeasEarly Ideas

Jules VerneJules Verne

““Journey to Journey to the Center of the Center of the Earth”the Earth”

Entered in Entered in IcelandIceland

Exited in ItalyExited in Italy

Information about the Information about the Earth’s Interior comes Earth’s Interior comes

from:from:MeteoritesMeteoritesVolcanoesVolcanoesSeismic Waves (“sound Seismic Waves (“sound

images”)images”)Tremendous Tremendous pressurepressure

enormous enormous heat (from natural heat (from natural radioactivity)radioactivity)

Meteor Crater (Arizona)Meteor Crater (Arizona)

Willamette MeteoriteWillamette Meteorite Found 1902,Found 1902,

in West Linnin West Linn Largest inLargest in

the U.S.A.the U.S.A. Sold and Sold and

nownowresides in resides in NYCNYC

VolcanoesVolcanoes E.g., Hawaiian “hotspot”E.g., Hawaiian “hotspot” Windows into theWindows into the

EarthEarth Samples 200km downSamples 200km down

(e.g., diamonds!)(e.g., diamonds!)

Seismic Seismic WavesWaves

Sound energySound energyfrom earthquakesfrom earthquakesand large and large explosionsexplosions

DEPTHSDEPTHS Top of MantleTop of Mantle

– 10 to 70 km (5 to 10 to 70 km (5 to 30 miles)30 miles)

Top of CoreTop of Core– 2,900 km (2000 2,900 km (2000

miles)miles) Center of EarthCenter of Earth

– 6,300 km (4,000 6,300 km (4,000 miles)miles)

Mt. Everest Mt. Everest 9 km 9 km high.high.

Marianas Trench Marianas Trench 11 km deep.11 km deep.

How do we know what’s How do we know what’s inside the Earth?inside the Earth?

How do we know what’s inside the How do we know what’s inside the Earth?Earth?

Direct ObservationsDirect Observations:: Exposures on surfaceExposures on surface

up from up from 50 km (30 50 km (30 miles) depthmiles) depth

DrillingDrilling to to 15 km 15 km (10 miles)(10 miles)

Volcanic MaterialVolcanic Material up up from from 200 km (120 200 km (120 miles) depthmiles) depth

How do we know what’s How do we know what’s inside the Earth?inside the Earth?

How do we know what’s How do we know what’s inside the Earth?inside the Earth?Indirect ObservationsIndirect Observations::

Magnetic FieldMagnetic Field Iron core.Iron core. Gravity FieldGravity Field Densities:Densities:

– Crust: 2 - 3 g/cmCrust: 2 - 3 g/cm33

– Mantle: 3.3 - Mantle: 3.3 - 5.8g/cm5.8g/cm33

– Core: 10.8 g/cmCore: 10.8 g/cm33

Earthquake Seismic Earthquake Seismic WavesWaves

Physical statePhysical state of crust, of crust, mantle, core.mantle, core.

LITHOSPHERELITHOSPHERE– rigidrigid outer shell outer shell – crust and upper mantle (~ 50 to crust and upper mantle (~ 50 to

200 km thick)200 km thick)– somewhat brittle, breakablesomewhat brittle, breakable– cold (like cold (like butterbutter out of fridge)out of fridge)

ASTHENOSPHEREASTHENOSPHERE– warmer, warmer, plasticplastic layer under layer under

lithospherelithosphere– mantle from ~ 150 to 700 kmmantle from ~ 150 to 700 km– squishy, plasticsquishy, plastic– warm (like warm (like softened buttersoftened butter))

LOWER MANTLELOWER MANTLE– Solid, Solid, but can flow over time!but can flow over time!– ~700 to 2900 km~700 to 2900 km

OUTER COREOUTER CORE– liquidliquid

INNER COREINNER CORE– solidsolid

Interior of Earth by StrengthInterior of Earth by Strength

Elevated Continents

Submerged Ocean Basins

Swimming Pool

Earth’s Mantle

Continental Crust

Earth’s Mantle

Types of CrustTypes of Crust

Continental CrustContinental Crust– 20 to 70 km (10 to 30 miles) 20 to 70 km (10 to 30 miles)

thick.thick.– Composed of highly evolved Composed of highly evolved

rocks, like granite (igneous), and rocks, like granite (igneous), and metamorphic rocks, squeezed and metamorphic rocks, squeezed and heated under mountain rangesheated under mountain ranges

Continental Crust

Earth’s Mantle

Oceanic Crust

Types of CrustTypes of Crust

Continental CrustContinental Crust– It is less dense, but thicker than It is less dense, but thicker than

oceanic crustoceanic crust Oceanic CrustOceanic Crust

– It is thinner, but more dense than It is thinner, but more dense than continental crust, so it sits lower than continental crust, so it sits lower than continental crust.continental crust.

– Composed of basalt (volcanic).Composed of basalt (volcanic).

Thick, Buoyant Continental Crust

Thin, Less-Buoyant Oceanic Crust

Thick Continental Crust Floats Higher

Thick Continental Crust Floats Higher

Thin Oceanic Crust Floats Lower

Mid

-Atl

anti

c Rid

ge

Water Fills in the Low Areas

And Hides Features on the Ocean

Floor!Water Fills in

the Low Areas

PLATE BOUNDARIESPLATE BOUNDARIES

PLATE TECTONICSPLATE TECTONICS TectonicsTectonics:: From the Greek “From the Greek “tectontecton”” builderbuilder “ “architect”architect” The study of The study of large featureslarge features on on

Earth’s surface and the Earth’s surface and the processesprocesses that formed them.that formed them.

Large Large featuresfeatures::– continents, mountain rangescontinents, mountain ranges– ocean basinsocean basins

and and processesprocesses::– earthquakesearthquakes– volcanic eruptionsvolcanic eruptions

These are due to movement of plates These are due to movement of plates of Earth’s outer shell.of Earth’s outer shell.

All resulting from All resulting from mantle convectionmantle convection

PLATE TECTONICSPLATE TECTONICS::

Cracked Egg Shell!