Name
Geology 141
Autumn, 2000
4 October, 2000 .
GE141: Physical Geology
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.
"Advance in science comes by laying
brick upon brick, not by sudden
erection of fairy palaces."
- J. S. Huxley
Geology 141: Autumn, 2000
First Hour Exam
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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; note that Questions
8 and 9 are linked - one may well help you with the other. Each question is worth 3 points; this section is worth
48 out of the total of 100 for the exam.
PLEASE READ EACH QUESTION AND RESPONSE CAREFULLY !
1. The most abundant two elements in the Earth's crust, by weight , are
a. silicon and iron
d. oxygen and silicon
b. silicon and aluminum
e. aluminum and oxygen
c. iron and oxygen
f. iron and nickel
2. The core of the Earth is believed to be comprised mainly of
a. iron and oxygen
d. silicon and iron
b. iron and nickel
e. aluminum and oxygen
c. oxygen and silicon
f. silicon and aluminum
3. The mantle of the Earth is believed to be about how thick?
a.12-15 km
d. 5000 km
b. 5-8 km
e. 2900 km
c. 40-70 km
f. 12,500 km
4. Which of the following is NOT a basis for what we believe about the interior of the Earth?
a. study of meteorites found on Earth.
b. study of lunar samples brought back by the Apollo missions to the Moon
c. theoretical studies of rock behavior under conditions of high pressure
d. studies of the behavior of seismic waves (from earthquakes) as they
bounce around inside the Earth.
e. studies of inclusions (xenoliths) in basaltic lavas found on Earth.
f. a late-night telephone call to Madame Cleo's Psychic Hotline
g. studies of rare rocks (ophiolites) in folded mountain ranges.
5. Iron and magnesium frequently substitute for each other in many mineral structures. This can
take place only because
a. their ions have the same charge and are almost the same size.
b. they're both about the same abundance in the Earth's composition.
c. they are only found in silicate minerals.
d. they are the two most abundant elements in the Earth's crust.
6. Over 50% of the entire crust of the Earth is made up of
a. native elements
d. sulfides and sulfates
b. carbonates
e. oxides and hydroxides
c. feldspars
7. The only non-silicate mineral group that is really important more for its bulk (abundance) in the
crust than its economic value is the
a. native elements
d. sulfides and sulfates
b. carbonates
e. oxides and hydroxides
c. feldspars
Geology 141: Autumn, 2000
First Hour Exam
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8. While hiking on Mount Hood in the Oregon Cascades last summer, you saw a cliff of massive
rock that looked quite similar to the following cartoon,
with large mineral grains surrounded by many smaller ones. You know now that this particular
rock was characterized by what is called a
a. porphyritic texture
c. volcanic texture
b. plutonic texture
d. clastic texture
9. The texture shown in the rock depicted in Question 8 is the product of
a. a rapid cooling process, in which the large grains cooled directly from
the magma, and the small grains cooled out of the volcanic gases.
b. a two-stage cooling process, in which the large grains crystallized
slowly, the finer-grained materials more quickly.
c. a slow cooling process, but the smaller grains had a higher melting
temperature than the larger grains.
d. lava that was chilled extremely quickly so that everything was frozen
"in place" the way it was in the lava.
10. The volcanic eruptions of Kilauea, in Hawaii, that we saw on the video in class, were
characterized mainly by
a. very low-viscosity flows of lavas that flowed to the coast.
b. explosive volcanic ash that buried the Hawaiian rain forests.
c. pyroclastic flows down the volcano mountainside, blasting away the
village of Makaopuhi on the flanks.
d. flows on the lava lake that demonstrated clearly that plate tectonics is
more myth than reality.
11. Most of the known active terrestrial volcanoes in the world are on the margins of the Pacific
Ocean because
a. these are zones where the oceanic lithosphere of the Pacific Ocean is
being pushed (subducted) beneath the adjacent land margins.
b. these are plate divergent zones, where new crustal material is being
created above mantle upwelling.
c. these are zones where there are lines of mantle plumes, or "hot spots",
that create new magma, the same way it does in Hawaii.
d. we just haven't yet found the ones that are in other places in the world,
though they almost certainly are there in large numbers.
12. While working in a region on the northwest Flank of the Himalaya in Tibet, you've found a
region of previously unknown granite that you can show extends over a total area of more than
360 square kilometers. Taking the name of a local village as the appropriate basis, you name this
new unit the
a. Zhongba stock
c. Zhongba batholith
b. Zhongba dike
d. Zhongba sill
Geology 141: Autumn, 2000
First Hour Exam
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13. Dikes and sills in continental regions, though plutonic, are much more commonly mafic than
felsic because
a. mafic magmas are much less viscous than felsic magmas.
b. mafic magmas are formed by melting of continental crust.
c. all plutonic rocks in the world are derived from mafic magmas.
d. they always cool in accordance with Bowen's Reaction Series.
14. What most people think of as "normal" volcanoes, such as Mt. Rainier in Washington State, Mt.
Fuji in Japan, Mt. Mayon in the Philippines, Mt. Vesuvius in Italy, or Popocatepetl in Mexico,
are all created by
a. repeated eruptions of explosive debris and viscous flows, that interlayer
to create a steep-sided cone-shaped mountain.
b. upward "blistering" of the crustal rocks over an igneous intrusion, which
periodically leaks a little lava out the top.
c. very fluid flows of lava like those we saw in the Hawaiian video.
d. processes that scientists don't yet understand.
15. The most important single factor in all chemical weathering processes is
a. whether or not the minerals are in Bowen's Reaction Series.
b. how old the mineral or rock is.
c. the presence of water.
d. the structure of the silica tetrahedra in the mineral.
e. whether the mineral is or is not a silicate at all.
16. The cements that bind sedimentary rocks together come from
a. magma from deep within the earth that seeps into all the cracks.
b. the chemical weathering of other minerals.
c. cosmic dust from outer space that settles through the Earth's atmosphere
and is deposited with the sediments, gluing them together.
d. gravitational attraction that pulls the grains towards each other until
they stick together.
Geology 141: Autumn, 2000
First Hour Exam
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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 52 points possible for this entire section.
17. In order for a substance to be considered a mineral, it has to meet four basic criteria. What ARE
these criteria? (5 points: 2-1-1-1)
1.
2.
3.
4.
18. The two principal gasses dissolved in most magmas are: (5 points: 3-2)
1.
2.
19. Though the estimated age of the Universe and what we believe about the age of our Solar System
is a strong hint that this is the case, what is the direct evidence that our Solar System, including
the Earth, is a second-generation star system? WHY does this evidence strongly indicate this is
true? (5 points)
20. What is the absolutely critical difference between chemical and mechanical weathering?
points)
The critical difference between chemical and mechanical weathering is that:
(5
Geology 141: Autumn, 2000
First Hour Exam
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21. What is the critical difference between weathering and erosion? (5 points)
22. In the chart below, I've indicated the size ranges for various clastic sediments. Name the
sediments that are characterized by those size clasts (I've given you the first), and identify the
sedimentary rocks that are created by the cementation and compaction of those sediments (10
points - 1 point each).
Size
|
Sediment Name |
Sedimentary Rock
|
|
> 256 mm |
Boulders
|
|
|
|
|
2 - 256 mm |
|
|
|
|
|
0.06 - 2.0 mm
|
|
|
|
|
|
0.004-0.06 mm
|
|
|
|
|
|
|
|
(massive)
<0.004 mm |
|-------------------------------|
|
(fissile)
|
|
23. Five critical factors that determine the ultimate character of a soil are:
(5 points, 1 point each)
Geology 141: Autumn, 2000
First Hour Exam
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24. Identify a sedimentary rock that is dominated by the mineral calcite. (2 points)
25. 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 absolutely no doubt about
what you are labeling. (10 points, 1 point each)
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:
Bay of Fundy
New Guinea
Quebec
Greenland
Ohio
Sumatra
West Virginia
Aleutian Islands
Cascade Range
Bay of Bengal
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.