Download First Hour Exam, Fall, 2001

Geology 141
Fall, 2001
Name
.
3 October, 2001
Ge141: Physical Processes
of Planet Earth
First Hour Examination
INSTRUCTIONS: Please read all instructions and questions
CAREFULLY and completely. If you do not understand a question as
it appears on the exam, PLEASE ASK FOR CLARIFICATION!!! It is
to YOUR benefit to do so. This examination is worth 100 points, or
10% of your overall semester grade. Exams will be graded as quickly
as possible; your individual point total will be entered on the last page
to ensure that only you know how well you did on the exam, unless
you choose to divulge that information to others.
"Those who can make you believe absurdities
can make you commit atrocities."
- Voltaire
Geology 141: Fall, 2001
First Hour Examination
... Page 2 ...
Section I: Multiple choice. Please circle the letter of the response that is
correct or that BEST answers the question or completes the statement. There
is ONLY ONE BEST ANSWER for each question. Each question is worth 3
points; this section is worth 60 out of the total of 100 for the exam.
PLEASE READ EACH QUESTION AND RESPONSE CAREFULLY !
1. The Earth and our solar system are believed by scientists to be about how old?
a. about 5-10 million years
c. about 5 billion years
b. about 10-12 billion years
d. about 12-15 billion years
2. The core of the Earth is composed of what is, by weight, the most abundant element in
the entire earth, and this element is
a. oxygen
c. silicon
e. sulfur
b. iron
d. magnesium
f. nickel
3. The most abundant element, by weight, in the continental crust is
a. oxygen
c. silicon
e. sulfur
b. iron
d. magnesium
f. nickel
4. The continental crust is about how thick?
a. 5-8 km thick
c. about 100 km thick
b. 40-70 km thick
d. about 2900 km thick
5. The major mineral groups are defined on the basis of
a. their chemistry
c. their structures
b. how rare they are
d. whether they contain water
6. A rock that has a texture consisting of large crystals surrounded by much smaller
crystals (as shown in the cartoon sketch below, or shown in the hornblende andesite of
Soufriere Hills Volcano in Montserrat) is said to be
a. pyroclastic
c. lithospheric
b. aesthenospheric
d. porphyritic
7. This kind of texture (that described in #6) is created by magmas that undergo
a. rapid cooling
c. mixing while they're cooling
b. slow cooling
d. a two-stage cooling process
8. Though most plutonic rocks tend to be felsic in character, dikes and sills are most often
mafic. This is because
a. they're usually only very small features.
b. they only occur over areas > 100 square kilometers in size.
c. the mafic magmas are very low in viscosity, allowing them to form these
relatively thin, tabular bodies.
d. they're natural bodies that occur along the coast of the Netherlands, where
only mafic magmas are common.
9. Intermediate magmas, such as those that erupted to form the hornblende andesite of
the Soufriere Hills Volcano, Montserrat, are generally created by
a. mixing of low-silica magmas with those of higher silica content.
b. melting of continental crustal rocks
c. partial melting of the upper mantle at divergent plate boundaries
d. molten material from the outer core
Geology 141: Fall, 2001
First Hour Examination
... Page 3 ...
10. A volcano that has a profile that looks like the cartoon sketch below would be
called what kind of volcano?
a. a stratovolcano
c. a cinder cone
b. a shield volcano
d. a pseudo-volcano
11. Examples of volcanoes that have this kind of shape include all of the following EXCEPT
a. Mauna Loa, Hawaii
c. Mt. Hood, Oregon
b. Fernandina, Galapagos Islands
d. Olympus Mons, Mars
12. New oceanic lithosphere (and hence, new lithospheric plates) is created at
a. subduction zones at the plate margins
b. the mid-oceanic rise and ridge system
c. lines of mantle plumes or "hot spots" that rise from deep in the mantle.
d. areas where two major continental masses are colliding.
13. Island arc systems are formed by the subduction of one oceanic plate beneath another.
Which of the following is NOT an island arc system?
a. the Kuril Islands
d. the Japanese islands
b. the Hawai'ian Islands
e. the Aleutian Islands
c. the Antilles, including Montserrat, at the eastern margin of the Caribbean Sea
14. Plate tectonics is driven by
a. differential heating of the Earth by the sun - so that the tropics expand and the
polar regions shrink.
b. volcanism that lifts up high mountains like the Andes, Rockies, and
Himalaya, pulling the plates away from each other in other areas.
c. upwelling deep in the mantle, caused by heat released by radioactive decay
d. the weight of the oceans pushing down on their basins, pushing out the
relatively plastic aesthenosphere underneath.
15. Iceland owes its existence to the fact that it lies
a. along a major convergence zone, where plates come together to push it up.
b. on a subduction zone, where volcanism is created.
c. atop a mantle plume that also occurs within a divergent plate boundary.
d. where vast amounts of winter sea ice come together and drop rocks and debris.
16. The two most common gasses in magmas are
a. hydrogen and oxygen
d. steam and carbon dioxide
b. helium and hydrogen
e. steam and silicon dioxide
c. methane and carbon dioxide
f. ammonia and carbon dioxide
17. Granite, as a rock, is restricted in occurrence to continents because
a. the felsic magma that is its parent is created by melting of continental rock.
b. volcanoes that erupt intermediate magmas are only found on continental
margins.
c. no one has looked for it beneath the deep ocean basins yet, so we don't know
whether it's down there.
d. granite is formed at all convergent plate boundaries, and all plate boundaries
in the oceans are divergent boundaries.
Geology 141: Fall, 2001
First Hour Examination
... Page 4 ...
18. The minerals in Bowen's Reaction Series are all susceptible to chemical weathering.
What can you say about their relative resistance to chemical weathering?
a. The minerals in Bowen's Reaction Series all have about the same resistance to
weathering.
b. Those at the bottom of the Series are the least resistant to weathering, and will
be the first to undergo weathering.
c. Those at the top of the Series are the least resistant to weathering, and will be
the first to undergo weathering.
d. Their resistance to weathering will depend on how steep the slopes are where
they occur - for instance, on a flat plain, or on a mountainside.
19. The critical difference between weathering and erosion is that
a. weathering alters minerals to forms more stable at low temperatures; erosion
alters them to forms more stable in wet conditions
b. weathering is a natural process; erosion is almost always the result of human
interference in the natural systems.
c. erosion alters rocks and minerals in place; weathering removes the materials.
d. weathering alters rocks and minerals in place; erosion removes the materials.
20. Soils form principally as a result of
a. erosion of underlying rocks and sediments.
b. deposition of rocks and sediments.
c. weathering of rocks and sediments.
d. human intervention, by introducing vegetation and water.
Geology 141: Fall, 2001
First Hour Examination
... Page 5 ...
Section II: Short answers, fill-ins, etc. Please respond to each question in the
most appropriate fashion. Please make your responses concise and to the
point, but thorough. There should be ample space provided for an adequate
response; PLEASE RESTRICT YOUR RESPONSES TO THE SPACE PROVIDED.
PLEASE ALSO write legibly; I CANNOT give any credit for responses I can't
read! The number of points for each question is indicated in parentheses after
the question; there are 40 points possible for this entire section. (And
PLEASE remember as well that, as promised on the syllabus, I WILL deduct a
point each time I see "volcanoe" or "techtonic!")
21. What are the four basic criteria that a substance must meet to be considered a mineral?
(5 points: 2-1-1-1)
1.
2.
3.
4.
22. Name (1 point), sketch (2 points) and label (2 points) the major structural building
block for all the silicate minerals.
Name:
Labeled sketch:
23. Why, once they're generated, are mafic magmas more likely than felsic magmas to make
it through to the ground surface? (5 points)
Geology 141: Fall, 2001
First Hour Examination
... Page 6 ...
24. Is concrete a rock? Why or why not? (5 points)
25. Name five (5) typical stratovolcanoes, from anywhere in the world. (5 points, 1 point
each)
1.
2.
3.
4.
5.
26. Why is the Himalaya where it is? That is, what is creating this great mountain range,
which includes the highest points on Earth? (5 points)
Geology 141: Fall, 2001
First Hour Examination
... Page 7 ...
27. On the maps on the following page (the maps are printed back-to-back), locate precisely
each of the following localities or features. FOR SMALL FEATURES OR LOCALITIES,
use a sharp arrow drawn from your label to the feature, so there can be no doubt about
what you are labeling. PLEASE remember that IT IS TO YOUR BENEFIT that
your label is clear enough that there is NO question as to your meaning or
intent! (10 points, 1 point each)
And YES, all labels must be correctly spelled for credit!
[ Since all you have to do is copy the name from the list below! ]
On the map of the U.S. & Canada: On the map of the world:
Idaho
Ural Mountains
Lake Ontario
Montserrat
Cascade Range
Kamchatka
Colorado
Persian Gulf
Georgia
Himalaya
Grade on exam: __________________ out of 100 possible*.
* If this is below 70, please see me within the next week !!!
PLEASE NOTE: After exams are graded, I will return your exam ONLY to you. It
will not be released to friends, roommates, your lab partner, or anyone else.
This is to ensure YOUR security and confidentiality.