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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!