Download Earth: A Unique Planet

Earth’s Layered Structure
Important Statistics
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The earth is not a sphere; it is an oblate
spheroid (wider at the equator)
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Hydrosphere: 71% of earth’s surface
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97% is oceans
3% is lakes/rivers
Two Types of Crust
1. Continental Crust
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about 30% of the Earth
Thickest layer (mountains)
Less dense made of Felsic Igneous rock
(sits higher than ocean water almost floating)
Rich in silicon
Most abundant mineral is quartz-very hard
Two Types of Crust Cont…
2. Oceanic Crust
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About 70% of the Earth
Thin layer & youngest
Dense made of Mafic (dark color) Igneous rock
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Rich in Iron and Magnesium
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Most abundant mineral is basalt
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Layers of the Earth’s Interior
Lithosphere
Outer layer of the Earth (crust & upper- mantel)
Crust- solid, outermost layer (continental/oceanic)
This layer sits on the mantle.
Layers of Earth’s Interior
Asthenosphere
200 km zone of mantle where rock is hot enough to flow
(this includes the mantle)
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Mantle: 2870 km thick layer below crust (largest
layer) made of a liquid plastic magma
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Outer Core: liquid layer of iron that generates the
Earth’s magnetic field
Inner Core: solid iron compressed from super high
pressure
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The Layers of the Earth
The Earth’s Interior
The earth is made up of layers.
 Studied by seismic waves.
 Seismic waves change speeds through
different layers.
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Proof of Layers
Seismic waves
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zones on earth’s surface where seismic waves
can’t be detected
– P-waves: fastest waves, deflect through inner
core. (hit inner core and deflect away) solids
and liquids
– S-waves: second fastest waves, don’t pass
through outer or inner core. (absorbed by outer
core) only through solids
*only p waves can travel all the way through earth
and s waves will hit a liquid layer and be deflected
so we can predict what certain layers of Earth are
liquid and others solid
The Earth as a Magnet
Earth has North and South magnetic
poles.
 Results from liquid iron in outer core.
 Movements in the outer core create a
magnetic field.
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