Geology 141
Spring, 1997
Name
3 March, 1997
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 your confidentiality.
"It's always a bad idea to fall into a habit of trying
to decide when you're going to give 100%, and
when you're not. If you're going to make it, you
have to give 100% all the time."
Geology 141: Spring, 1997
First Hour Exam
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- Don White, folk singer
Geology 141: Spring, 1997
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. 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 three most abundant elements in the whole Earth, by weight, are
a. iron, lead and zinc
c. iron, oxygen and silicon
b. nickel, magnesium, and lead
d. iron, hydrogen and helium
2. The continental crust is
a. about 5-8 km thick and composed of basaltic igneous rocks.
b. typically 40-70 km thick and composed of more silica-rich rocks.
c. about 2900 km thick and composed of iron-rich silicates and oxides.
d. about 1200 km thick and composed of mostly iron and nickel, below
thin surface layers of silicate and carbonate rocks.
3. The mantle of the Earth is
a. about 5-8 km thick and composed of basaltic igneous rocks.
b. typically 40-70 km thick and composed of more silica-rich rocks.
c. about 2900 km thick and composed of iron-rich silicates and oxides.
d. about 1200 km thick and composed of mostly iron and nickel, below
thin surface layers of silicate and carbonate rocks.
4. To be a mineral, a substance must meet all of the following criteria EXCEPT
a. it must be naturally occurring
b. it must be an inorganic solid
c. it must have a crystalline structure
d. it must have a constant chemical composition, or one that varies within
set limits
e. it must contain silica tetrahedra in some internal arrangement
5. Non-silicate minerals are usually most important for
a. the fact that they make up most of the moon.
b. their volume in making up the Earth's core.
c. the fact that they're the most abundant in the Earth's crust.
d. the fact that they include many valuable mineral commodities.
e. the fact that they are the dominant minerals formed by living things.
6. The most abundant minerals in all the Earth's crust, comprising over 50%
of the total bulk of both the oceanic and continental crust, are the
a. feldspars
d. carbonates
b. native elements
e. oxides and hydroxides
c. sulfates
f. sulfides
7. The viscosity of a magma is determined by all of the following EXCEPT
a. silica content
c. temperature
b. the shape of the volcano
d. dissolved gasses
8. An igneous rock in which all the mineral grains are 1 centimeter across
a. must have cooled very slowly and is clearly a plutonic rock
b. will always be made up of minerals low in Bowen's Reaction Series
c. probably came from a mafic magma
d. all of the above
Geology 141: Spring, 1997
e. none of the above
First Hour Exam
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Geology 141: Spring, 1997
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9. A volcanic rock is derived from a magma containing about 50% silica (SiO2)
by weight. Most of the mineral grains in this rock will probably be
a. quartz, biotite and orthoclase
b. olivine, pyroxene, and Ca-rich plagioclase
c. quartz, olivine and hornblende
d. clays, quartz and hematite
e. you can't say based on this information
10. Almost all the active volcanoes in the world are located
a. on the margins of lithospheric plates.
b. randomly throughout the world.
c. at divergent plate margins.
d. over "hot spots" or mantle plumes from the molten outer core.
e. in the Mediterranean and Caribbean Seas and their margins.
11. Almost all plant nutrient in soils, with only one exception, are
a. brought into the soil by rainwater, especially from acid rain.
b. "fixed" from non-organic sources, like air, by micro-organisms.
c. derived from chemical weathering of minerals in the soil.
d. only brought in from windblown dust, volcanic ash and rain.
12. The soil horizon that has the maximum level of chemical weathering and
of biological activity is the
a. A horizon b. B horizonc. C horizon d. parent material
13. When people buy potting mix for houseplants or "topsoil" from a commercial
source, they are really purchasing a synthetic imitation of the soil
a. A horizon b. B horizonc. C horizon d. parent material
14. In discussing hydrolysis as a chemical weathering process, we used a fairly
simplified equation to illustrate the effect it has on a generalized silicate
mineral:
silicate + water -->
+
+
+
Which of the following was NOT one of the products of this reaction?
a. clay minerals
d. iron or aluminum oxides/hydroxides
b. ions in solution
e. free silica (SiO2) in solution
c. sulfide or sulfate minerals
15. A typical clastic sedimentary rock would be a
a. sandstone
c. granite
b. limestone
d. chert
16. Limestones as sedimentary rocks are composed mainly of what mineral
group?
a. silicates
d. oxides and hydroxides
b. carbonates
e. halides
c. sulfides
f. sulfates and phosphates
17. Abundant trans-ferric elements on Earth provide clear evidence for
a. the age of the "Big Bang" and origin of the Universe.
b. our Solar System being at least a second-generation star system.
c. the core of the Earth being composed mainly of iron and nickel.
d. how magmas originate deep within the Earth.
18. The Earth and Solar System are believed by scientists to be about how old?
Geology 141: Spring, 1997
a. 10,000 years
b. 1 million years
First Hour Exam
c. 5 million years
d. 5 billion years
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Geology 141: Spring, 1997
First Hour Exam
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19. Minerals are classified into different major groups based on their
a. crystal structure
c. organic or inorganic qualities
b. importance to plants and animals d. chemical composition
20. Minerals of a major mineral group are classified into different subgroups
based on their
a. crystal structure
c. organic or inorganic qualities
b. importance to plants and animals d. chemical composition
Geology 141: Spring, 1997
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 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.
21. Below is a cartoon sketch of something we discussed in class. What is it,
and why is it important in geology? (5 points) (Identify and label its component
parts for 2 bonus points!)
22. How are mafic, intermediate and felsic magmas formed? Why do they tend
to rise once formed? (10 points)
Geology 141: Spring, 1997
First Hour Exam
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Geology 141: Spring, 1997
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23. Sketch comparative profiles of a shield volcano and a stratovolcano. How
do volcanoes form? What is the reason these two volcano types have such
different profiles? (10 points)
24. Why do minerals at or near the top of Bowen's Reaction Series weather
more readily than those at the bottom of the Series? (5 points)
Geology 141: Spring, 1997
First Hour Exam
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25. On the maps on the following page (the maps are printed back-to-back),
locate precisely each of the following localities or features. WHEN IT IS
NECESSARY FOR CLARITY, use a sharp arrow drawn from your label to
the feature. (10 points, 1 point each)
All labels must be correctly spelled for credit!
On the map of the U.S.:
Nova Scotia
Lake Superior
Oregon
Virginia
Ohio
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On the map of the world:
Andes Mountains
Ural Mountains
Kuril Islands
India
Iceland
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Grade on exam: __________________ out of 100 possible.
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.