Geology 001A West Valley College

Physical Geology R. Lopez

Study Questions:Physical Properties of the Earth’s Interior

1) Because we cannot directly sample the deep Earth, we must use indirect means to study the Earth’s interior. This branch of geology is called _______________.

2) What are seismic waves? What are the two main types of seismic waves?

3) Contrast and compare the two types of body waves. How do P waves (primary) and S waves (shear) travel through the Earth?

4) Only ________________ waves travel through liquid.

5) S waves are faster than P waves. True or False?

6) What is seismic refraction?

7) Material with higher elasticity in the Earth will make seismic waves travel slower or faster?

8) Define a Low Velocity Layer and a High Velocity Layer.

9) By using seismic refraction, geophysicists determined that seismic waves increase to 8 km/sec at the crust-mantle boundary. What is this boundary called?

10) From about 125 km to 225 km depth in the Earth, seismic waves slow down. This layer is called the Low Velocity Zone in the mantle. What is this zone known as in Plate Tectonic Theory?

11) What is a phase transition (mineral collapse) and how does this explain the sudden increase in seismic wave velocity below 410 km depth and at 660 km depth.

12) Using seismic waves, how do we know that the outer core is liquid?

13) Explain the P-wave and S-wave shadows.

14) What is the Geothermal Gradient? What is the rate in the crust and what is the rate in the mantle?

15) What is the temperature on the base of the crust? The Core-Mantle Boundary? And the Inner Core?

16) What is seismic tomography. How do seismologists use seismic tomography to image the deep earth?

17) Earth is surrounded by a region of magnetic force called ________.

18) What is a dipole in reference to an atom?

19) Do the magnetic field poles coincide with the geographic poles?

20) Where is the strength of Earth’s magnetic field the strongest?

21) Are the magnetic poles stationary or do they change over time?

22) Where is Earth’s magnetic field generated?

23) How is Earth’s magnetic field generated?

24) What are magnetic reversals?

25) How do rocks record strength and direction of the magnetic field?

26) What is the Curie point?

27) The study of ancient magnetic fields is called ______.

28) Where does most of the evidence for magnetic reversals come from?

29) Are magnetic reversals worldwide events?

30) What is the average time between magnetic reversals?

31) How will the temporary loss of Earth’s magnetic field affect life on Earth?