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JOURNEY TO THE CENTER OF
THE EARTH
Chapter 3
Plate Tectonics
Study Plan
• Our Neighborhood
• The Magnetic Field
• The Atmosphere
• Land and Oceans
• What is the Earth made of?
• Layers
• The Lithosphere and the Asthenosphere
William Gilbert (1544-1603)
 Discovered
Magnetism
1. Every magnet has
2 poles
2. Like magnet poles
Repel each other,
while
Unlike poles attract.
The Magnetic Field of Earth
The Atmosphere
• 78% nitrogen
• 21% oxygen
• 1% argon, carbon dioxide, ozone,
methane,….
Land and Oceans
What is the Earth made of?
• Organic material
• Minerals
• Glasses
• Rocks
• Metals
• Melts
• Volatiles
Layers
• Deepest mine shaft 2 mi below the
surface in South Africa
• Crust
• Mantle
• core
Clues from earthquakes
Pressure and Temperature
• Geothermal gradient (15-50 deg. Celcius
every 1,000 m in the upper crust)
• 4,700 deg. Celcius at the core
What are the layers made of?
• The Crust: oceanic vs. continental
– Which is thicker? Denser?
• Crust-mantle boundary - MOHO
• The Mantle – upper mantle, transition
zone, lower mantle
– Most is solid rock
• The Core – outer core and the inner core
– Which one is liquid? Solid?
Lithosphere vs. Asthenosphere
• Crust + uppermost mantle
Structure
3 Types of Plate Margins
Mechanisms of Plate Tectonics
Evidence from rocks
• Ocean rocks
• Land rocks
Evidence from Fossils
Lystrosaurus – Africa, S.
America, India
Ichthyosaur
Evidence from Mountain ranges
Evidence from the Ocean Basin
Fig. 6-5, p.129