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Layers of the Earth
Unit 2: Tectonic Processes
Ms. Thind
Geog 12
How old is the earth?
Approximately 4.5 BILLION
years old!
70% Water, 30% Land
What is it made of?
• Mantle
• Continental
and Oceanic
Crust
• Core
• Lithosphere
• Centrosphere
• Mesosphere
• Asthenosphere
• Atmosphere
• Hydrosphere
Centrosphere
 “core” center of the earth
 Consists of inner core and outer core
 Composed of iron, nickel, and heavy metals
 Core in solid state due to ↑ pressure
Mesosphere
 Known as the mantle
 Solid layer between earth’s core and then asthenosphere
Asthenosphere
 Plastic layer of the upper mantle directly below lithosphere
Lithosphere
 Outer layer that surrounds the earth
 Brittle- can be cracked, warped and buckled
 Ends at the “moho” (Mohorovicic discontinuity): defined line
of contact
 Within the lithosphere:
- Crust: thin outer layer of rock
- Continental Crust
- Oceanic Crust
Hydrosphere
 Covering of water on the earth
 Has irregularities due to the lithosphere
Atmosphere
• True outer covering of the earth
• Mixture of gases: nitrogen and oxygen
Earth’s Layers:
 How are the earth’s layers
similar to an egg?
 Shell=crust
 Egg white=mantle
 Yolk=core