Plate Tectonics: Discussion Questions

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Chapter 6 Homework Questions for Review 1. Why is the Earth not perfectly round? It bulges at the equator. Its shape is technically an oblate spheroid. 2. What are some of the most common elements composing the Earth? Earth’s most common elements are oxygen, silicon, aluminum, magnesium, and iron. 3. How do we know that the Earth has a liquid core? Why is the inner core solid even though it is hotter than the outer liquid core? We know that the Earth has a liquid core because of seismic waves. A type of seismic wave known as an "S" wave or Shear wave moves side-to-side in a shearing motion and does not propagate through liquid only through solid. "S" waves are often blocked or reflected by the inner core and it is therefore thought…show more content…
12. How does the fact that the Earth has a magnetic field help provide evidence for the theory of plate tectonics? The magnetic “structure” of the Earth is changing because of plate tectonics. 13. What were the main components of the atmosphere when the Earth formed, and what are the main components today? How and why did they change? The atmosphere of Earth is primarily a mixture of nitrogen and oxygen. Earth’s original atmosphere was probably just hydrogen and helium. They changed because the molecules of hydrogen and helium were moving so fast that they eventually escaped the Earth. 14. Explain how the greenhouse effect works and how it relates to global warming. The greenhouse effect is when radiation at visible wavelengths passes freely through the atmosphere and is absorbed at the ground. The ground heats up and emits infrared radiation. Atmospheric gases absorb the infrared radiation and warm the atmosphere, which in turn warms the ground. 15. What is ozone? Why is it important? The oxygen in our atmosphere is important for breathing but also acts as a protection that shields us from harsh solar ultraviolet radiation. Much of this comes from another molecular form of oxygen, O(3), or
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