Download First Hour Exam, Spring, 2005

Geology 141
Name
.
Spring, 2005
2005
2 March,
GE141: Physical Processes
of Planet Earth
First Hour
Examination
This examination is worth 150 points, or 15.0% 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.
"Often people attempt to
live their lives backwards: They try to HAVE more things
or more money, in order to DO more of what they want, so
they will BE happier. The way it actually works is the
reverse. You must first BE who you really are, then DO
what you need to do, in order to HAVE what you want."
---Margaret
Young
Geology 141, Spring, 2005
First Hour Examination
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INSTRUCTIONS: PLEASE read the questions CAREFULLY and completely. If you do not
understand something as it appears on the exam,
PLEASE ASK FOR
CLARIFICATION!! It is to YOUR benefit to do so.
Please respond to each question in the most appropriate fashion. Please make your
responses concise and to the point, but thorough; use sketch diagrams any place you believe
that they may help explain your response. There should be ample space provided for
an adequate response to each question; KINDLY RESTRICT YOUR
RESPONSES TO THE SPACE PROVIDED. PLEASE ALSO remember that 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.
(And PLEASE remember as well that, as promised on the syllabus, as painful as it
is for me, I WILL deduct a point each time I see "volcanoe" or "techtonic!")
1. Approximately when do scientists believe the Universe came into existence, in the "Big
Bang?"
years ago (2 points)
2. About when do scientists believe OUR solar system, and the Earth, came into existence?
years ago (3 points)
3. What is the direct evidence that our solar system is a second-generation star system
(see #4 before become verbose!)?
(2 points)
4. WHY does this indicate that our solar system was created from the debris of a preexisting star? (3 points)
5. The most abundant element in the Earth as a whole (~35% by weight) is
(2 points)
6. The most abundant two elements in the Earth's crust (~47% by weight and ~27% by
weight, respectively) are
and
(3 points: 2-1)
7. The dominant mineral group in the Earth's crust, comprising some 95% by weight of
all crustal rocks, is the
(3 points)
8. The only OTHER mineral group that's most important for its bulk in the crust,
comprising about 3% of all crustal rocks (or over half of all those minerals not in the
group you identified in #7), is the
Geology 141, Spring, 2005
First Hour Examination
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(2 points)
9. What is the difference between silicon and silica? (5 points)
10. What are two major pairs of elements that are important in ionic substitutions in the
dominant mineral group that makes up the outermost layer of the Earth? (Match one
major element with another that commonly substitutes for it in the crystal structures; 4
points - 1 point each.)
a.
and
.
b.
and
.
11. What are the four defining criteria a substance must meet to be considered a mineral?
(6 points: 2-2-1-1)
1.
2.
3.
4.
12. What is the elemental composition of the core of the Earth? What is the difference
between the INNER core and the OUTER core? (5 points: 3-2)
Composition:
Difference:
13. How thick is the oceanic crust?
How thick is typical continental crust?
km. (2 points)
km. (3 points)
Geology 141, Spring, 2005
14.
First Hour Examination
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Identify THREE major lines of evidence that support the combined theories of
continental drift and plate tectonics, and indicate clearly HOW each of these kinds of
evidence support those theories. (10 points)
1.
2.
3.
Geology 141, Spring, 2005
First Hour Examination
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15. What major plate tectonic processes are taking place at the Mid-Oceanic Rise and Ridge
System, and why are they important? (10 points)
16. What are the three major categories of rocks, and what is a defining characteristic of
each? (10 points: 4-3-3)
1.
2.
3.
Geology 141, Spring, 2005
First Hour Examination
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17. Three major factors determine the viscosity of a magma. What are those three factors,
and how does each affect the viscosity? (i.e., Does more of a given factor INcrease or
DEcrease the viscosity of a given magma?) (List the factor first, then indicate in the
space provided whether an increase in this factor makes the magma more or less
viscous; 10 points)
1.
2.
3.
17. What part of the Earth is the source for all mafic magmas, like those in Hawai'i, Iceland,
the Mid-Oceanic Rise and Ridge system, or the Galápagos Islands? (5 points)
18. In a porphyritic volcanic rock composed mainly of hornblende, Na-plagioclase and a
potassium feldspar, which of these is MOST likely to be found as a phenocryst, and why?
(10 points)
19. What is believed to be the mechanism by which the Hawaiian Island chain has come into
existence? Why is this NOT an island arc system? (10 points)
Geology 141, Spring, 2005
First Hour Examination
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20. Why are there so many volcanoes in Ecuador and throughout the Andes Mountains, as
well as in SW Alaska, Oregon, and Washington? (10 points)
Geology 141, Spring, 2005
First Hour Examination
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21. Please fill in the names of the parent magma types as well as of the rocks that are
produced by crystallization of each of the three major magma types, both volcanic and
plutonic. (9 points)
Magma type | Silica content |
|
|
|
>65%
|
|
|
|
|
|
55-65%
|
|
|
|
|
|
45-55%
|
|
|
Volcanic Rock
|
|
|
|
|
|
|
|
|
|
Plutonic Rock
.
.
.
.
22. If mantle plumes are responsible for both the relatively benign eruptions of Hawai'i and
the catastrophically explosive eruptions of the Yellowstone and Long Valley Calderas,
why are the resulting eruptions so very, very different? (6 points)
Geology 141, Spring, 2005
First Hour Examination
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23. What is the difference between DIKES and SILLS as plutonic igneous rock bodies? (Use
a sketch diagram is you think this will help!) (5 points)
24. 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:
Nova Scotia
Washington, D. C.
Alberta
Arizona
Cascade Range
On the map of the world:
Andes Mountains
Peru
London, England
Albania
Bulgaria
Grade on exam: __________________ out of 150 possible*.
* If this is below 100, 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.