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Earth’s Internal Processes

Learn about Earth's interior through seismic wave observations, drilling into the oceanic crust, and studying density changes in layers. Discover the composition and behavior of Earth's core, mantle, and lithosphere. Develop a deeper understanding of the planet we call home.

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Earth’s Internal Processes

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  1. Earth’s Internal Processes Section 3 Earth’s Interior

  2. Inside the Earth • Scientists learn about the interior by: • Drilling a hole 200 m into the oceanic crust • Studying the behavior of seismic waves • Earth’s interior is not the same throughout • Earthquake waves arrive at different times

  3. Earthquake Observations • A boundary that marks a density change between layers is called a discontinuity.

  4. Think – Pair - Share • Why do you think that scientists attempted to drill through oceanic crust instead of continental crust?

  5. Earthquake Observations • Seismic recording stations like ours record seismic wave data. • Waves refract when they encounter sharp changes in density.

  6. Shadow Zones • P- and S- waves spread out from an epicenter • Waves travel through 105 degrees of arc • Shadow Zone – “dead zone” between 105 and 140 degrees • From 140 to 180 degrees only P-waves are recorded

  7. Earth’s Interior 3 Shadow Zones

  8. Earth’s Core • Shadow zones reveal • A layer in the interior may be absorbing waves • S-waves turn into P-like waves • S-waves travel only through solids • Outer core may be a liquid

  9. Inner Core • P-waves are refracted as they pass through the inner core • Inner core must be denser than outer core • Pressure of outer core keeps the inner core solid • Outer core remains liquid because of the high temperatures

  10. Composition of Layers • Layers become denser with depth • Lithosphere – crust & upper mantle • Rocky materials – mostly silicates • Asthenosphere – weaker layer under lithosphere • Plasticlike layer • Mantle – divided into upper and lower • Made of silicates

  11. Composition (con’t) • Core – divided into outer and inner • Mostly nickel and iron • Earth may have formed from meteorite-like material • Material was forced together by gravity and melted • Densest materials are in the core, less dense ones float on the surface

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  13. Post PowerPoint • What do scientists know about Earth’s interior? • How do they know this?

  14. Section Check Question 1 What is Earth’s core made of? Answer Earth’s core is primarily made of metallic material such as iron and nickel.

  15. Section Check Question 2 Earth’s internal layers become _______ with depth. A. cooler B. darker C. denser D. lighter

  16. Section Check Answer The answer is C.

  17. Section Check Question 3 Why can’t S-waves penetrate the liquid outer core? Answer S-wave only travel through solids. This suggests that the outer core is in a liquid state.

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