Earth’s
Interior
CH 4.1 Prentice Hall
Pgs 108-114
How do Scientists know?
–Based on inferences
–Scientists use seismic
waves: waves produced
by earthquakes
• They act differently as
they travel through the
Earth.
Earth’s Interior
Earth’s Interior (Crust)
Crust
•
•
•
•
Solid “Rocky” outer layer
Thinnest layer (5-40km)
Oxygen & Silicon
Two types of Crust
– Ocean: made of Basalt
– Continental: made of Granite
– Ocean crust is denser
Lithosphere
• “Rock” Sphere (15-300km)
• Part of the lower crust and upper
mantle
• Rigid layer that floats on the
asthenosphere.
Asthenosphere
• Greek for “weak” sphere (250km)
• Can flow, Plastic/Fluid Like
• Acts like silly putty.
Layers
of
Earth
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Mantle
• Thickest layer (2,900km)
• Half way to the center of the
Earth
• Composed of:
– Silicon (Si)
– Oxygen (O)
--Magnesium (Mg)
--Iron (Fe)
• Temperature and Pressure increase
with depth.
Layers
of
Earth
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The Outer Core
• Third Layer (2,250km)
• Molten Metal (2,200˚C)
• Iron and Nickel
• Plastic/Fluid Like
– Behaves like a liquid.
Layers
of
Earth
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The Inner Core
• Rigid: extreme pressure
keeps the atoms from
spreading apart
• Center of the Earth
(1,200km)
– Hottest Layer (5,000˚C)
• Dense, solid metal ball
– Iron and Nickel
Layers
of
Earth
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