Geology 141
Spring, 1999
Name
8 March, 1999
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.
"The earth sciences are pre-eminently the disciplines that
define the natural limits of resources and ecosystems - limits
that communities must respect if they are to survive and
prosper."
- Robert Frodeman
Geology 141: Spring, 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. The mantle of the Earth is
a. approximately 2900 km thick.
b. believed to be composed of iron- and magnesium-rich silicates at the
top, and oxides at depth.
c. the source for most, if not all, mafic and ultramafic magmas.
d. that portion of the inner Earth immediately below the crust.
e. all of the above
f. none of the above.
3. The critical difference between the inner and outer core is that
a. the inner core is composed of iron, the outer core is mostly nickel.
b. the inner core is mostly nickel, while the outer core is iron.
c. the inner core is iron and nickel, and the outer core is silicates.
d. the inner core is oxides, while the outer core is silicates.
e. the inner core is solid, while the outer core is molten.
4. The critical differences between rocks and minerals is that
a. rocks can be man-made; minerals have to be naturally occurring.
b. rocks can occur anywhere; minerals only occur on Earth.
c. minerals have to have constant composition and structure, rocks don't.
d. minerals don't always have to contain silica; rocks always do contain it.
5. Magma originates by
a. mixing of mud with very hot water from deep within the earth.
b. development of "feeder dikes" that drain molten material from the core.
c. plate tectonic processes active in the Earth's core.
d. unknown processes that we don't understand at all.
e. melting of pre-existing rocks.
6. A magma of 68% silica (SiO2) content crystallizes deep underground. Typical
minerals you would expect in the resulting rock would include
a. olivine, pyroxene and calcium plagioclase.
b. clays, hematite, limonite, and the minerals in bauxite.
c. quartz, muscovite, orthoclase and sodium plagioclase feldspar.
d. you would not expect any minerals to form in such a rock.
e. there is no way to predict what minerals would be present.
7. The viscosity of a magma is determined by all of the following except for
a. its temperature.
c. its dissolved gas content.
b. the radioactivity level.
d. its chemistry, especially silica content.
Geology 141: Spring, 1999
First Hour Exam
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8. The only non-silicate mineral group that is important more for its volume in
the crust than for its economic significance is the
a. oxides and hydroxides c. native elements e. carbonates
b. phosphates
d. sulfides
f. sulfates
Geology 141: Spring, 1999
First Hour Exam
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9. As of the writing of this exam, there are 18 suspected planets around stars
other than our sun. In the year 2016, YOU are part of a scientific team that
is evaluating the first photographic telescopic images of one of the smaller,
rocky planets around one of these other stars. You see a large mountain that
shows a distinctive profile that looks like the cartoon below. Without
10.
11.
12.
13.
14.
any additional information, you can tell that this landform is a volcano
formed by
a. explosive volcanic eruptions of highly viscous magma, perhaps like that
of Eldfell, on Heimaey, Iceland.
b. fluid, low-viscosity magmas, like those of Hawaii or Fernandina in the
Galapagos Islands.
c. a mix of high- and medium-viscosity magmas, like those of the Cascade
volcanoes (Mt. Rainier, Mount St. Helens, Mt. Shasta, etc.).
d. eruptions that can't bear any resemblance to any of those on Earth.
The lithosphere consists of the
a. rocks of the uppermost crust that are accessible to us.
b. plastic, deformable material in the mantle that provides the source for
mafic magmas and pushes the overlying layers around.
c. portion of the Earth's surface that isn't covered by water.
d. relatively rigid plates, consisting of the crust and uppermost mantle.
Volcanoes are
a. the sites where magmas originate and come out of the Earth.
b. typically mountains built up of countless layers of volcanic flows and
pyroclastics, derived from magmas originating deep in the Earth.
c. giant hills or mountains that have been pushed up like a giant bubble,
by the pressure of magmas underneath.
d. steep-sided high mountains of any origin.
The minerals that are at the top of Bowen's Reaction Series are those that
a. have very low melting points, and therefore form phenocrysts in
porphyritic igneous rocks.
b. are very stable at the Earth's surface, and weather very slowly or not
at all.
c. have very high melting points, and therefore high crystallization
temperatures.
d. have very high silica contents.
Of all the following plant nutrients found in typical soils, the only one that
is not derived from the chemical weathering of minerals is
a. calcium (Ca)
d. iron (Fe)
b. phosphorus (P)
e. nitrogen (N)
c. potassium (K)
f. sulfur (S)
Sedimentary rocks derived from the bits and pieces of pre-existing rocks (e.g.,
sand, gravel and the like) that have been cemented together into new rocks
are called
Geology 141: Spring, 1999
First Hour Exam
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a. clastic sedimentary rocks
c. lithographed sedimentary rocks
b. chemical sedimentary rocks d. biogenic (organic) sedimentary rocks
Geology 141: Spring, 1999
First Hour Exam
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15. The cements that glue these rocks (from #14) together come from
a. the secondary minerals formed by chemical weathering processes.
b. high-silica magmas that seep in between the grains underground.
c. chemicals secreted by micro-organisms living in the sediments.
d. partial melting of the edges of the mineral and rocks bits.
16. Limestones are very common sedimentary rocks. Some are derived from
chemical processes, but most of them are derived from partial or complete
recrystallization of the remains of organisms. The dominant mineral that
makes up most of a typical limestone is in which major group of minerals?
a. oxides and hydroxides c. native elements e. carbonates
b. phosphates
d. sulfides
f. sulfates
17. Zones where tectonic plates are pulling apart are called zones of
a. convergence
c. continuity
e. lithification
b. divergence
d. volcanism
f. hydrolysis
18. Flocculation is a process in which
a. larger clastic grains require greater energy levels to move them around.
b. sedimentary grains deposited in a basin are cemented and compacted
into rock.
c. volcanic gasses expand during an eruption to produce a frothy volcanic
rock.
d. clay particles in suspension clump together in salty water, and settle out
relatively quickly.
19. 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
20. The soil in an ancient landscape has been eroding for thousands of years,
accumulating to great thicknesses of sediments in a deep ocean basin.
Ultimately, this sediment is pushed down deep within the Earth by plate
tectonic processes, where some of it is heated to great temperatures, and
eventually melts. When this molten material cools and hardens, the end
product is what kind of rock?
a. igneous rock
b. sedimentary rock
c. metamorphic rock
d. you can't say without more information about the silica content and
other factors of the materials involved.
Geology 141: Spring, 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 most abundant two gasses in most magmas are: (5 points: 3-2)
22. Five typical stratovolcanoes, from anywhere in the world, are (5 points,
1 point each)
23. (a) What is the critical difference between chemical and mechanical weathering
processes? (5 points)
(b) Why is water so important to weathering? (5 points)
Geology 141: Spring, 1999
First Hour Exam
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24. In discussing chemical weathering and the formation of soils, we identified the
five basic factors that are critical to the formation of any soil and expressed
them in a shorthand formula:
S =  {P, T, C, B, t}
What are each of the five factors expressed in this equation? (5 points,
1 point each)
P=
T=
C=
B=
t=
25.
What is the critical difference between chemical
metamorphism as processes that change rocks? (5 points)
weathering
and
26. On the maps on the following pages (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 it from the list below! ]
On the map of the U.S.:
Wisconsin
Lake Ontario
Georgia
Nova Scotia
Cascade Range
On the map of the world:
Andes Mountains
Kamchatka
Sumatra
Hawaiian Islands
Iceland
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Grade on exam: __________________ out of 100 possible*.
* If this is below 70, please see me within the next week !!!
Geology 141: Spring, 1999
First Hour Exam
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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.