Chapter 4. Interior of the Earth

After reading the chapter and attending all lectures and viewing the films, you should be able to:
1. explain how geologists make predictions about the center of the earth when we have never been able to drill or mine deeper than about 15 km deep compared to the 6370 km radius of the earth.
2. describe how we can make inferences about the density of the earth using studies of gravity, moment of inertia, and magnetic field.
3. explain, in general terms, how the passage of seismic waves through the earth allows us to infer that there are layers of the earth which differ in depth and composition.
4. (in connection with objective #3) be able to define refraction and reflection of seismic waves.
5. sketch a general model of the structure of the interior of the earth, labeling the crust, mantle, outer coreinner core, asthenosphere, and lithosphere;  include the approximate depth/thickness of each layer.
6. describe why the shadow zone exists.
7. locate the Mohorovicic and Guttenberg discontinuities.
8. characterize and distinguish between mafic and ultramafic rocks.
9. discuss how and why the temperature of the earth changes with depth, a concept known as the geothermal gradient.
10. compare the use of seismic tomography with a CAT-scan of a human body to explain our knowledge of the interior of the earth.
11. contrast the hypotheses of whole mantle convection and two-layered mantle convection to explain how the mantle distributes heat.
12. hypothesize regarding what the source of the earth's internal heat might be.
13. describe how the convection of the earth's core is the likely source of the earth's magnetic field.

Critical Thinking Questions and Activities:
1. Using the hypotheses regarding the earth's heat source, extrapolate to other planets . . . does Mars have such mantle convection?  What might this suggest about the possible of subterranean life on the Red Planet?
2. Spheres A and B have equal mass and volumes.  The mass of A is evenly distributed whereas the mass of B increases toward the center.  If both spheres are rolled down an inclined plank, which will reach the bottom first?  Name the property responsible for the difference.