Name
Geology 141
Spring, 2000
6 March, 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.
"What was solid earth has become
the sea, and solid ground has
issued from the bosom of the
waters."
- Ovid (in Metamorphoses)
Geology 141: Autumn, 1999
First Hour Exam
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Geology 141: Autumn, 1999
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 most abundant element in the Earth's crust, by weight as well as volume, is
a. silicon
c. iron
e. aluminum
b. oxygen
d. nickel
f. carbon
2. Evidence that our solar system, including the Sun and Earth, are recycled from a preexisting star system that exploded in a supernova is provided by the fact that
a. iron is the most abundant element in the Earth as a whole.
b. the Earth has more water than any other known system.
c. the Earth has abundant elements that are above iron on the period table.
d. silicate minerals make up most of the Earth's crust.
3. New lithospheric plates are created by
a. subduction of oceanic plates on continental margins.
b. igneous activity along the mid-oceanic rise and ridge system.
c. deposition of sedimentary rocks over old volcanic systems.
d. weathering and erosion of old lithospheric plates.
4. The margins of the Pacific Ocean are dominated by zones where
a. lithospheric plates are sliding past each other on transform boundaries.
b. lithospheric plates are pulling apart on zones of divergence.
c. lithospheric plates are coming together in zones of convergence.
d. there is almost no tectonic plate activity.
5. The major mineral groups are defined on the basis of their
a. internal structure c. mode of origin
b. chemistry
d. temperature and pressure stability fields
6. SUBgroups of the major groups are defined on the basis of their
a. internal structure c. mode of origin
b. chemistry
d. temperature and pressure stability fields
7. The only non-silicate mineral group that is more important as a rock-forming mineral
group than as an economic mineral group is the
a. feldspars
d. carbonates
b. sulfates
e. native elements
c. sulfides
f. oxides and hydroxides
8. Arguably the most important group of minerals, making up more than 50% of the crust
by themselves, are the
a. feldspars
d. carbonates
b. sulfates
e. native elements
c. sulfides
f. oxides and hydroxides
9. Magmas that ultimately become igneous rocks come from
a. melting of pre-existing rocks.
b. in the liquid outer core.
c. underground reservoirs of molten material left over from the original
formation of the Earth.
d. melting of the inside of mountains, that then become volcanoes.
Geology 141: Autumn, 1999
First Hour Exam
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10. As plutonic rock bodies, stocks are
a. tabular bodies, usually mafic, that cut across pre-existing rock units or layers.
b. tabular bodies, usually mafic, that were intruded in between older rock layers.
c. any irregular intrusive rock body that occurs over a surface area of < 100 km2
d. intrusive rock bodies occurring over an area >100 km2
e. those that contain significant levels of economically valuable minerals.
11. A beautiful and typical stratovolcano is
a. Mauna Kea, Hawai'i
d. Olympus Mons, Mars
b. Mauna Loa, Hawai'i
e. Mt. Mayon, Philippines
c. Kilauea, Hawai'i
f. Fernandina, Galapagos Islands
12. A magma begins cooling underground, and as it cools, crystals of a mineral (for
example, hornblende) begin to form. As time passes, these get bigger in the magma.
The magma is pushed out through a volcano to become lava, and then all of it hardens
fairly quickly, in a matter of a few days. This will produce
a. a typical granite
b. a porphyritic volcanic rock with hornblende phenocrysts.
c. an obsidian, or volcanic glass
d. a typical batholith as the lava flows out across the land surface.
13. The cements that hold sedimentary rocks together come from
a. secondary minerals formed by chemical weathering processes.
b. fractionation of silica-rich magmas deep underground.
c. partial melting of the minerals in the sediments.
d. collapse of the crystal structures in the minerals, as a result of high pressures.
14. Felsic magmas are more likely than mafic magmas to produce plutonic rocks because
a. felsic magmas originate much deeper within the Earth than mafic magmas.
b. felsic magmas are found everywhere, while mafic magmas are fairly rare.
c. felsic magmas are much more viscous than mafic magmas.
d. felsic magmas are always plutonic, mafic magmas always volcanic.
15. The eruption of Eldfell in 1973, on the island of Heimaey, Iceland, was characterized by
a. building of a large cinder cone on a fissure, basaltic (mafic) magmas, and a
relatively peaceful (as volcanoes go) eruption that the islands successfully turned
away from the harbor and village.
b. a violently explosive eruption that swept almost all of the village of
Vestmannaeyjar off the island and into the ocean.
c. eruption of enormous clouds of pale gray volcanic ash that buried the entire
town, much the same way that Vesuvius buried Pompeii; hundreds of people
also died after being buried alive in the Eldfell eruption.
d. a river of lava that swept the entire town away, burned it, or buried it under
volcanic rock, making the island uninhabitable.
16. The soil horizon that is the site of greatest chemical weathering and the greatest
biological activity in the soil is the
a. A horizon
c. C horizon
b. B horizon
d. parent material
e. You can't say for sure without more information
17. Of the 20 to 25 elemental nutrients that plants need to derive from soils, the only one
that is not derived from the chemical weathering of minerals is
Geology 141: Autumn, 1999
a. potassium c. sulfur
b. phosphorus
d. nitrogen
First Hour Exam
e. iron
g. magnesium
f. calcium
h. zinc
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Geology 141: Autumn, 1999
First Hour Exam
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18. The reason chemical weathering is slow in deserts like the Sahara or Namib in Africa, or
the Mojave in southeastern California, is because
a. chemical weathering is more effective at lower temperatures.
b. there is nothing to remove the weathering products, so the process stops.
c. there needs to be large changes in temperatures, so processes like ice-wedging
can work.
d. chemical weathering processes almost all require water to take place.
19. A biogenic sedimentary rock composed almost entirely of carbonate minerals (usually
mostly calcite) is called a
a. chert
c. coal
e. borax
b. mudstone
d. limestone
f. bauxite
20. Sand and mud accumulate off the mouth of a big river where it enters the ocean. Over
millions of years, this deposit gets thicker and deeper, and tectonic processes force it
deep down into the earth along a subduction zone. It gets hotter and hotter as it is
squeezed and pushed increasingly deeply, and eventually it melts. When this molten
material cools and hardens again, it will most likely be a
a. mudstone
b. metamorphic rock
c. B horizon in a soil
d. granite
e. meteorite
Geology 141: Autumn, 1999
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 40 points possible for this entire section.
21. The three fundamental factors that determine the viscosity of magmas are: (5 points: 22-1)
22. The soils that are created in any area are a result of interactions between five principal
factors. We used a shorthand mathematical formula to describe this relationship.
What are each of the factors involved ? (5 points - 1 point each)
23. In describing hydrolysis as a chemical weathering process, we used a generalized
chemical equation to show the net effects of hydrolysis on a generalized silicate
mineral in a rock. Fill in the blanks below with the principal products of this process.
(5 points: 2-1-1-1)
Generic silicate + H2O -->
+
23.
+
+
Three factors that can vary independently, making metamorphic rocks extremely
complex (and interesting!) are: (5 points: 2-2-1)
Geology 141: Autumn, 1999
First Hour Exam
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24. In the chart below, I've indicated the size ranges for various clastic sediments. Name
the sediments that are characterized by those size clasts, and identify the sedimentary
rocks that are created by the cementation and compaction of those sediments (10 points
- 1 point for each + 1 for trying).
Size
|
Sediment Name
|
Sedimentary Rock
|
|
2 - 256 mm
|
|
|
|
|
|
0.06 - 2.0 mm
|
|
|
|
|
|
0.004 - 0.06 mm
|
|
|
|
|
|
|
|
(massive)
<0.004 mm
|
|--------------------------------------------|
|
(fissile)
|
|
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 no doubt about
what you are labeling. (10 points, 1 point each)
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:
Oregon
Lake Ontario
Sierra Nevada
Missouri
Georgia
On the map of the world:
Andes Mountains
Jamaica
Iceland
Philippine Islands
Bay of Bengal
Grade on exam: __________________ out of 100 possible*.
* If this is below 70, please see me within the next week !!!
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.