Earth’s
Interior
How do Scientists know?
• About the interior?
• Using observations to make a
claim about something we
can’t see directly.
– Based on inferences.
– Scientists use seismic waveswaves produced by
earthquakes.
• They act differently as they travel
through the Earth and they
reveal the different layers.
A Journey to the Center
• Temperature:
– Temperature increases as you
descend towards the center.
• Pressure:
– Pressure is the force pushing
on a surface or area.
– Pressure increases as you
descend towards the center.
• More rock layers are on top of
you pressing down.
Earth’s Compositional Layers
Crust
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Solid “Rocky” outer layer
Thinnest layer (5-40km)
Oxygen & Silicon
Two types of Crust
– 1. Ocean- Basalt
– 2. Continental- Granite
– 3. Ocean crust is denser than cont.
Layers
of
Earth
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Mantle
• Second Major Layer
– Thickest layer. (2,900km)
• Half way to the center of the
Earth.
• Composed of:
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–
–
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Silicon (Si)
Oxygen (O)
Magnesium (Mg)
Iron (Fe)
• Temperature and Pressure
increase with depth.
Layers
of
Earth
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The Core
• Third Layer (2,250km)
• Mostly Iron & Nickel
• Makes up one third of the Earth’s mass.
Layers
of
Earth
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Earth’s Physical Layers
Lithosphere
• “Rock” Sphere. (15-300km)
• Includes the Crust
• Rigid layer that floats on the
asthenosphere.
• It is broken into moving plates
Layers
of
Earth
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Asthenopsphere
• “Weak” sphere. (250km)
• Can flow, Plastic/Fluid Like
• Acts like silly putty.
• Convections currents cause it to flow
Layers
of
Earth
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Mesosphere
• Lower part of the mantle
• Solid rock
• Flows slower than the asthenosphere
Layers
of
Earth
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The Outer Core
• Third Layer (2,250km)
• Molten Metal (2,200˚C)
• 1. 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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