Delwar’s GEOS 100

Exam 2 Review

 

Exam 2 is on Friday 17th October, 2003.

Exam 2 will cover Chapters 6, 7, 8, 9 & 10

 

Read through the text, see the chapter-wise presentations, and review your own class notes. Don’t forget the Prentice Hall website for Tarbuck and Lutgens 7th Ed text.

 

CHAPTER 6

Sedimentary Rocks

 

1.                  What is diagenesis? Give an example.

2.                  Compaction is an important lithification process with which type of sediment size?

3.                  Distinguish between conglomerate and breccia.

4.                  What are the dominant minerals in Detrital sedimentary rocks? Why are these abundant?

5.                  What is the basis of classifying sedimentary rocks? What property do we use to characterize different detrital sedimentary rocks?

6.                  What is fissility as observed in shale?

7.                  How are the degree of sorting and rounding related to transport of sand grains?

8.                  How the chemical sedimentary rocks are distinguished?

9.                  How evaporite forms? Name an example of evaporite deposit.

10.              Distinguish between clastic and nonclastic textures? What type of texture is common to all detrital sedimentary rocks?

11.              In which way coal is different from other biochemical rocks?

12.              Some igneous rocks closely resembles nonclastic sedimentary rocks. How would you differentiate the two?

13.              How do current ripple marks differ from wave ripple marks?

14.              List some conditions that helps preserve the organisms as fossils.

15.              What sedimentary rock will react with dilute HCl (hydrochloric acid)?

16.              What type of fossilization process was involved in case of:

a.       a leaf preserved as a thin carbon film

b.      a log where the internal porse and cavities are filled with mineral matter.

c.       human footprints in claystone.

 

CHAPTER 7

Metamorphic Rocks

1.                  What is metamorphic rock? What are the agents that change the rocks? Why heat is considered most important agent?

2.                  What is the temperature window for metamorphism? What do you think will happen to the rock  if the temperature rises above the upper limit?

3.                  In what ways the parent rocks could affect the metamorphic process?

4.                  What is directed pressure? What is the role of it in foliation?

5.                  How would you distinguish between slate and phyllite?

6.                  Distinguish between contact and regional metamorphism? In plate tectonic setting where would you find what? Which process do you think creates greatest quantity of metamorphic rocks?

7.                  Name the rocks:

a.            foliated and composed predominantly of platy minerals.

b.           calcite-rich nonfoliated.

c.            very fine grained and foliated with excellent rock cleavage.

d.           composed of alternating bands of light and dark silicate minerals.

 

8.                  What is migmatite? How does it form?

9.                  What is impact metamorphism? What is the enrgy source for this type of metamorphism?

 

CHAPTER 8

Geologic Time

 

1.                  What is the basis of building the geologic time scale?

2.                  Distinguish between the numerical (absolute) and relative dating?

3.                  How did we calculated the age of the Earth as 4.6 billion years? What type of rock and what type of dating technique was used for calculating the age?

4.                  How the law of superposition is used in dating? Where would you use the principle of cross-cutting relationship?

5.                  Refer to figure 8.4 on p. 219 in the text and answer the following questions:

a.         Is fault A older or younger than the sandstone layer?

b.         Is dike A older or younger than the sandstone layer?

c.         Was the conglomerate deposited before or after fault A?

d.         Was the conglomerate deposited before or after fault B?

e.         Which fault is older, A or B?

f.           Is dike A older or younger than the batholith?

 

6.                  When you find an unconformity between two parallel sedimentary rock layers, what would you call it?

7.                  Distingusih between angular unconformity, disconformity, and nonconformity?

8.                  What do you understand by the term correlation?

9.                  Are fossils useful in correlation?

10.              When did humans developed?

11.              Why is radiometric method most reliable dating technique?

12.              Taking help from the slide on how to calculate age of a rock using radioactivity, do the following example problem.

a.         A hypothetical radioactive isotope has a half-life of 20,000 years. The ratio of radioactive parent and stable daughter product is 1:2. Find out how old is the rock containing the radioactive material. How many half-lives have elapsed to get to this ratio?

 

13.              Why it is difficult to date sedimentary rocks? Which rock type will give us better dates if used for radiometric dating?

14.              Why we don’t we have a complete geological succession starting from Cambrian to Quaternary period?

15.              What hypothesis (model) do we use to explain the extinction of dinosaurs at the end of cretaceous period? What supporting evidence do we have so far?

 

CHAPTER  9

Mass Wasting

 

1.                   What is the controlling factor of mass wasting?

2.                  In which way water affects the mass wasting process?

3.                  How mass wasting is different from erosion?

4.                  Why angle of repose is important?

5.                  How earthquakes are related to mass wasting?

6.                  In which way rock fall and debris fall different?

7.                  What do you understand by rock avalanche and debris flow?

8.                  Distinguish among slide, fall and flow?

9.                  What factors led to the massive rock slide at Gros Ventre, Wyoming?

10.              What are the possible evidences that you can expect to see if creep is affecting a slope?

11.              What would you do to remove pore water from an unstable slope to make it stable?

12.              Do you think that making the slopes less steeper in general will enhance the stability of the slopes?

13.              Which is better:

a.                   foliations for the slope?

b.                  Foliations against the slope?

 

 

 

 

CHAPTER 10

Running Water and Contamination

 

1.                  Over the oceans, evaporation exceeds precipitation. Then why the sea level is not dropping?

2.                  A stream originates at 2000 meters above sea level and travels 250 km to the ocean (0 meters). What is the gradient?

3.                  What happens to stream velocity when the discharge increases?

4.                  What is the best shape of stream efficiency?

5.                  How the stream velocity could affect transportation?

6.                  How the surface and groundwater is connected? Do you think that if one gets polluted the other one will eventually turn bad?

7.                  What is a drainage divide? What is the approximate area drained by the Mississippi River?

8.                  What do you think might happen to the pesticide that we use over time? There are some that will degrade, but what will happen to the persistent fraction?

9.                   What do you think that we should do to keep our surface water and groundwater pure?

10.              Have you heard about the pollution of Kalamazoo River by PCB (polychlorinated biphenyl)? It is now mixed with the sediments and it is hard to break it down to other forms. What do you think we should have done to keep the river non-polluted?

 

 

If you have gone through this review, and the class review session, luck will be with you to get you through the exam.

 

Good Luck!