Geology 1009
Exam 1 Name
1.
In historical geology, we often say, “The present is the key to the past.” Explain why this is important to historical
geology. (5 pts.)
2.
Explain which types of plants and animals are more likely to become fossils and why. (5 pts.)
3.
Explain what the environment of deposition is. (5 pts.)
4.
Explain how you could interpret the environment of deposition and paleoecology of a rock layer. (10 pts.)
a. What can you tell about the past by looking at a rock?
b. What would you look for and what would it tell you about the ancient environment.
5.
Explain why, of the three rock types, only sedimentary rocks get their own chapter in the textbook. (5 pts.)
6.
Correlate the sedimentary rocks in the three columns below. Explain the techniques used to correlate the rocks.
(How did you determine which rock layers from one location connect with rock layers from the other? Describe at
least two types of evidence you could look for to support your correlation.) (10 pts.)
(SEE PAPER VERSION HANDED OUT IN CLASS FOR CORRELATION COLUMNS)
7.
In the rocks in column A above, explain what happened to sea level and how you know. (10 pts.)
8.
Describe the sediments (or sedimentary rocks) that would be found from the shore to the edge of the continental
shelf in a tropical environment. You should draw a cross section to illustrate this. (10 pts.)
9.
A rift is a place where two continents are pulling apart. Rifts commonly open a little bit and then stop creating a
“failed rift”. Describe the rocks and structures you would find in a failed rift. (Hints: Think about what happens when
two plates pull apart. A “failed rift” starts to pull apart and then stops, so what does a young rift look like? (Hint: an
ocean basin never forms.) What types of rocks would be present? What kinds of geologic structures (folds, faults,
etc.) would you find? You should draw a cross section to illustrate this. (10 pts.)
10. An ophiolite is made of a piece of the ocean floor on a continent.
a. Explain how you can tell it was part of the ocean floor. (Hint: Describe the types of rocks that make up the ocean
b.
floor and crust, and how they are structured, you may wish to use a drawing.) (10 pts.)
Explain how the ophiolite ended up on top of a continent. (5 pts.)
11. Describe the geologic history of the area shown on p. 232-234 of the lab manual. You should start with the
Precambrian and address each period up to the present. You should include the environment of deposition as well
as any other geologic events such as igneous intrusions, volcanic eruptions, folding, and faulting. If the rocks
indicate a tectonic event (like rifting or subduction) has occurred, you should indicate that as well. (10 pts.)
12. Accreted terranes are often found along continental margins, explain how a geologist would be able to identify an
accreted terrane (how would you know it didn’t belong to the rest of the continent? (5 pts.)