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Earth’s Interior

Explore Earth's layers - from the crust to the inner core - and learn how seismic waves and magnetic fields reveal its secrets. Discover the formation and composition of our planet in this fascinating journey.

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Earth’s Interior

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  1. Earth’s Interior Link for intro animation: http://www.precisiongraphics.com/portfolio/animation/

  2. Earth began to form in a process called accretion (gathering), where dust and debris collide and stick together to form a large mass.

  3. Eventually the mass got large enough to be called a Planetesimal (planet building block)

  4. The planetesimal began to cool as it spun through space.

  5. Oblate spheroid forms- The spinning motion of the young, developing Earth caused it to form into a sphere that bulges in the center. 7900 miles 7926 miles

  6. How do we know about Earth’s Interior? • Drilling • Earth’s Magnetic Field • Seismic Waves

  7. Drilling into the Earth • Humans have been able to drill down about 12 km (approximately 7.6 miles) into the Earth’s crust. • We have never drilled into the mantle, outer core, or inner core.

  8. Why are there different layers? • Earth’s main heat engine: 1. radioactive decay (Uranium, Potassium, Thorium). 2. Pressure from asteroid hits. • Differentiation (layering) of Earth’s interior is due to gravity and differing densities.

  9. Earth’s 4 Layers • Crust • Mantle • Outer core • Inner core

  10. Crust • Solid, rigid layer mostly Oxygen & Silicon (SiO2). • Depth of 7-70 km. • Two types: Oceanic and Continental

  11. Earth’s Crust

  12. Mantle • Plastic-like with liquid properties • Composed mostly of iron, silicon, and magnesium • Depth of 2890 km (from the surface) • 1000 °C Thickest of Earth’s Layers!

  13. Earth’s Mantle

  14. Outer Core • Liquid • Composed of iron and nickel • Depth of 5150 km (from the surface) • 3700 °C

  15. Earth’s Outer Core

  16. Inner Core • Solid • Composed of iron and nickel • Extends to a depth of 6371 km (from the surface) • 4300 °C

  17. Ooblek • Observations -Write observations and conclusion in booklets titled Ooblek: • Before the addition of water, is cornstarch a solid, liquid, or gas? • When you try to pour the mixture into your hand, does the mixture behave like a solid, liquid, or gas? Explain • When you try to roll the mixture into a ball and apply pressure, does the mixture act like a solid, liquid , or gas? Explain • Conclusion: • From your observations and notes on Earth’s interior, compare Ooblek to Earth’s core. How does Ooblek help explain the difference between Earth’s outer core and inner core?

  18. Earth’s Inner Core

  19. How the Earth Moves Lithosphere-Made up of the crust and the uppermost portion of the mantle. Asthenosphere-Plastic-like and made up of the upper mantle.

  20. Movement of the liquid outer core of the Earth generates a strong magnetic field that surrounds the planet. This causes the Earth to act much like a large magnet, with the poles of the magnet located near the poles of the Earth.

  21. Earth’s Magnetic Field Our magnetic field is called the magnetosphere. It stretches out through the atmosphere and acts as a protective barrier to deadly, high-energy solar radiation.

  22. Earth’s Magnetic Field The Earth’s magnetic field allows us to use compasses to locate direction on the planet. A small magnetic needle that is allowed to spin freely aligns itself with the Earth’s magnetic field and points to the magnetic North Pole.

  23. The point of origin of an earthquake is called the Focus.The spot on the surface of the Earth directly above it is called the Epicenter.

  24. Seismic Waves Seismic wave: the energy released during an earthquake which travels through the Earth. 3 Types: * Primary (P) waves * Secondary (S) waves * Surface waves

  25. Primary Waves Primary waves, also known as P-waves, • Travel through the Earth by compressing and expanding. • Can travel through solids, liquids, and gases. • Are the fastest type of seismic wave, they are always detected first by a seismograph.

  26. Secondary waves, also known as S-waves. • Travel in an up-and-down pattern much like the waves that move through water. • Move much more slowly than P-waves • Can only travel through solid material, not liquids and gases. Secondary Waves

  27. Surface Waves Surface waves are produced as a rolling motion of ground along the surface of the Earth. Surface waves are the most destructive of all seismic waves.

  28. Waves Tell Us Earth’s Composition. Remember: • P-waves can travel through solids, liquids, and gases, while S-waves can only travel through solids. • We noticed that P-waves pass through the entire Earth, while S-waves can disappear. • So we know what Earth’s layers are made of !!!

  29. Seismic Waves Data from many earthquakes has shown that S-waves disappear when they encounter the liquid outer core. As P waves pass from one type of material into another, they are refracted (or bent slightly).

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