Earth Materials, Processes and Environments

GEOL‑1121    Fall 2015

Review Questions for

3^rd Lecture Test

Metamorphism and Metamorphic Rocks (Chapter 8)

1) What is metamorphism?  How does it differ from igneous and sedimentary rock-forming processes?  What types of materials form metamorphic rocks? 

2) What are the important agents of metamorphism?  How do they cause instability and change in the rock material? Why are some of the minerals more easily changed than others?  Give examples.

3) What is the difference between lithostatic and directed (differential) pressure?  What is the cause of each pressure type?  How do these types of pressure produce distinct textures in metamorphic rocks?

4) What are the geothermal and geobaric gradients?  Provide estimates of these gradients in the upper crust?  Describe the source of these increases in temperature and pressure.  Be able to calculate the temperature and pressure at various depths.

5) List and describe the different types of metamorphism.  Draw a chart showing the pressure and temperature conditions under which each type occurs.  Also draw and label the areas of igneous and sedimentary rock formation on the chart.

6) Describe how certain economic mineral deposits are formed by contact metamorphism.  Why is contact metamorphism usually limited in extent?

7) Compare and contrast burial metamorphism and lithification.  At which depths do each of these processes occur?

8) Describe the basis for the classification of metamorphic rocks.  Compare and contrast foliated and nonfoliated metamorphic rocks.  What information can be obtained from metamorphic rocks?   

9) Most of the rocks of the Blue Ridge Mountains have been highly metamorphosed.  Describe the cause of this metamorphism.  Why are the Blue Ridge rocks higher grade than the metamorphic rocks of younger mountain ranges like the Himalayas and Rocky Mountains?

10) Describe how index minerals are used to determine the intensity of metamorphism. Describe how the Al₂SiO₅ polymorphs (kyanite, andalusite, and sillimanite) are commonly used as index minerals.  Give examples of two other index minerals.

11) Describe and compare metamorphic facies and zones.  What is the blueschist facies and how does it form?

12) Does a metamorphic rock that formed under directed stress always display foliation?  Explain and give some examples.

13) List the most likely parent rock types (protoliths) for: slate, graphite schist, marble and quartzite.

14) Name and describe the tectonic plate boundaries where metamorphism commonly occurs.

15) Define the following terms: hornfel, mylonite, foliation, schistosity, slaty cleavage, gneissic layering, granoblastic, slate, schist, gneiss and metamorphic grade.

Earthquakes (Chapter 9)

1) What is an earthquake?  How does the Elastic Rebound Theory explain why earthquakes occur?  Compare and contrast elastic and brittle behavior and how they relate to earthquakes.

2) Why do most earthquakes occur in the upper mantle and crust at depths of less than

       100 kilometers (~60 miles)?  Describe the plate tectonic locations where earthquakes most commonly occur.

3) What type of plate tectonic boundary is the San Andreas Fault?  Why do so many earthquakes occur along this fault?  Why is it so dangerous? 

4) Describe the different types of seismic waves.  Explain how particle motion and velocity differ for each type.  Which seismic waves are unable to pass through liquids?  Why are these waves blocked?  Which type of seismic waves cause the most damage?

5) How is the magnitude and intensity of an earthquake measured?  What is a seismograph?

6) Compare and contrast the Mercalli and Richter Scales.  Which measurement provides better scientific data?  Explain.

7) Compare and contrast epicenter and focus. Can these two ever be located at the same point?  If they can, when will this occur?

8) Describe how the difference in velocity of seismic waves is used to locate earthquakes.  Why does it take more than one seismic station to locate an earthquake?  Make a drawing to show how the location is determined. 

9) Describe some of the causes of destruction associated with earthquakes.  What are some of the ways in which damage can be reduced or prevented?  List the following locations from safest to most dangerous during an earthquake: glass greenhouse, concrete building, wooden house and open field.  Explain your selections.

10) Describe some of the ways a building can be made more earthquake resistant.

11) What is a tsunami?  How does it form?  Why are they more common along the Pacific coastal margin?

12) Describe some of the ways scientists can predict earthquakes.  Describe some examples of earthquake precursors.    

13) Describe the seismic evidence that is used to determine the composition and nature of       the core, mantle and crust. 

14) Define the following terms: liquefaction, P‑waves, S‑waves, surface waves, tsunami, elastic rebound, elastic and brittle behavior, MOHO, Low-Velocity

       Zone, paleoseismology and the P- and S-wave Shadow Zones.