Download Sample exam 1

Geology 101
Sample exam 1 (Chapters 1 – 5)
Open textbook, notes, labs and handouts, no other textbooks or collaboration.
You have 50 minutes to complete the 50-point exam.
Short answer; answer all questions.
1. With whom are you doing your poster project (solo is fine, but provide your
partner’s last name)? What topic are you covering (be as specific as you can)?
2. The two reasons besides curiosity that humans study geology are:
3. How are steep cliffs indicated on a topographic map?
4. (6 points) Fill in the empty squares in the table below:
Volcano type
Magma
composition
Eruptive style
Resurgent caldera
Any, but typically
felsic
Extremely violent
Usual tectonic
setting
Subduction zone
or continental hot
spot
Composite
(stratovolcano)
Shield volcano
5. The ______________________________________ plate is
subducting under the ____________________________________ plate
off the Washington coast. Specific names will count towards full credit on this
question.
6. a. What sort of luster does mineral X have?
b. What streak does mineral X have?
7. a. Mineral X does not scratch glass, but the edge of a piece of glass scratches
the mineral. Compared to glass, mineral X is (choose one):
a. harder
b. softer
c. the same hardness
d. can’t tell
b. If you look carefully at mineral X, you will see that the “mineral” is actually
made of lots of small crystals. Assuming that you could pull off one of those small
crystals, what would you do to test whether that crystal showed crystal habit
(growth) or cleavage?
8. What phenocryst (give the mineral name) would be found in rhyolite, the
felsic volcanic rock?
9. On topographic maps, how do contour lines alone show a mountaintop?
10. On geologic maps, how are areas of different type/color of rocks indicated?
Cross-section question — Draw a cross-section of the Cascadia Subduction
Zone (that is, the subduction zone that we live on). Include the following features
for full credit:
• Indicate the west side of your sketch with a “W” and the east side with an “E”
• The two plates with their names involved in the subduction
• The arrows showing which way the plates are moving
• A Cascades volcano and its magma source
• The submarine trench
Essay questions — answer two of the following and please circle the number
of the questions chosen. Make sure your answer is in paragraph form.
11. Fidalgo Island (north of Seattle by fifty miles) is made of peridotite and
gabbro on its west side; as you go east on the island, the rock becomes basalt in
the form of sheeted dikes. Where did the rocks of Fidalgo Island originate, and
how does the rock information help you answer that question? What rock would
you expect to find on the eastern edge of the island?
12. Olivine (iron silicate) can be used as an iron ore by melting a large quantity of
it in a heated container, then heating the melted material further to break the
iron away from the silica (recall that silica is chemically the same as quartz). The
molten silica is then simply poured off the top of the liquid in the container,
leaving nothing but molten iron behind. Explain how this technique works, and
use the word “density” in your answer.
13. The town of Lynden lies 50 km (30 miles) west of Mt. Baker, on the Nooksack
River, which originates on Mt. Baker. Lynden is separated from Mt. Baker by
Sumas Mountain. Order the following volcanic hazards from most severe to
least severe, and give reasons for your ordering: a) pyroclastic flow and blast,
b) lahar, c) flooding, and d) tephra (ash) fall. If you believe two of the hazards are
equally dangerous (or not dangerous), you should state that clearly.
14. On the map of the Aegean Sea below, I’ve marked four volcanoes (the
triangles). In order from west to east they are: Methana (2258 years ago), Milos
(1860 years ago), Santorini (59 years ago), and Nisyros (121 years ago). Are these
volcanoes the result of a hotspot or a subduction zone? Choose one origin,
and use evidence from the map and the ages to argue your case. In addition, if
you believe them to be caused by a hotspot, use an arrow to show the motion of
the plate on which they exist. If you believe them to be caused by a subduction
zone, draw where you believe the plate boundary is, and use the appropriate
marks to indicate a subduction.