Geology 141 (B): Fall, 2007 Second Hour Examination ... Page 12 ...
Geology 141(B) Name
Autumn, 2007 9 November, 2007
GE141: Earth & Environment ~
Second Hour Examination
INSTRUCTIONS: PLEASE read the instructions and questions CAREFULLY and completely. If you do not understand a question as it appears on the exam, PLEASE ASK ME FOR CLARIFICATION!! It is to YOUR benefit to do so. This examination is worth 175 points, or 17.5% 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.
"We ask ourselves, who am I to be brilliant, gorgeous, talented and fabulous? Actually, who are you not to be? You are a child of God. Your playing small doesn't serve the world."
- Nelson Mandela
Section I: Multiple-choice. Please circle the letter of the correct or best response to each question. Each question is worth 5 points; the section as a whole is worth 100 points of the 175 for the exam.
1. The most abundant element, by weight, in the Earth's crust is
a. silicon c. oxygen e. magnesium
b. iron d. aluminum f. copper
2. The basic major groups of minerals are classified according to
a. their silica content.
b. whether or not they're useful to humankind.
c. their chemical composition.
d. their physical structure.
3. The driving force behind plate tectonics is
a. convection cells within the upper mantle.
b. mantle plumes or "hot spots."
c. magnetic attraction of nearby continents.
d. flow in the liquid outer core.
e. reversals in the Earth's magnetic field.
4. Pyroclastic flows are
a. rapid flows of superheated mafic lavas in flood basalts and shield volcanoes.
b. hot blasts of gas and solid volcanic debris, up to 500ºC and 100 mph, that are
typical of intermediate (andesitic) volcanic eruptions.
c. volcanic mudflows, created by melting snows or heavy rains on ash deposits.
d. slow flows of blocky lava, consisting of solid chunks in a viscous melt.
5. The San Andreas Fault of California is created by
a. subduction of the Pacific Plate beneath the North American Plate.
b. sea-floor spreading that's pulling everything west of the fault away from
the rest of North America.
c. an offset in the East Pacific Rise from the Gulf of California to the northern
California coast, as a transform fault.
d. a major hotspot (mantle plume) midway between San Francisco and Los
Angeles.
6. Iceland as a volcanic island is particularly large because
a. it occurs above a particularly active subduction zone in the mid-Atlantic.
b. it both overlies a mantle plume ("hot spot") AND is part of the mid-oceanic
rise and ridge system (MORRS).
c. it is a remnant of continental crust from the earliest formation of the Earth.
d. it is formed from plate convergence between the North American and
Eurasian plates.
e. it is actually part of the North American Shield separated as the Atlantic
Ocean formed.
7. The rocks of coastal Maine are part of what is called Avalonia by geologists, and are separated from the geology of the rest of the state by the Norumbega Fault; Avalonia is a classic example of a(n)
a. accreted terrane c. pillow lava belt e. rift valley
b. Benioff zone d. subduction zone f. hot spot
8. Clays in soils are the product of
a. mechanical weathering of iron and aluminum oxides and hydroxides.
b. chemical weathering of silicate minerals.
c. abrasion of rocks against each other as they're rubbed together over time.
d. metamorphism of igneous rocks as a result of heat and pressure.
9. Nitrogen and sulfur are two elements that plants need to obtain from soils in relatively large quantities. These are critically important to the plants for
a. disease resistance c. structural strength
b. protein synthesis d. flowering
10. Of the nearly 20 elements that plants need to absorb through their roots from the soils, the ONLY one that is not derived from the chemical weathering of minerals is
a. potassium c. iron e. nitrogen
b. sulfur d. phosphorus f. calcium
11. A biogenic sedimentary rock formed from the remains of corals, shells and foraminifera would be a
a. chert c. shale e. mudstone
b. limestone d. coal f. congolomerate
12. The difference between the concepts of metamorphic grade and metamorphic
facies is that
a. grade is an index of how hard the rock is, whereas facies refers to how much it
has changed from its parent material.
b. grade is a general appraisal of how much the rock has changed, whereas facies
refers to what it looks like - e.g., foliated vs. non-foliated, etc.
c. grade refers to metamorphic changes to sedimentary rocks, whereas facies
refers to the effects of metamorphism on igneous or other metamorphic rocks.
d. grade is a general appraisal of how much the rock has changed - from a little to
a lot - whereas facies actually allows differentiation of pressure and
temperature effects.
13. Minerals that are found only, or almost only, in metamorphic rocks will include all of the following except
a. kyanite c. actinolite e. garnet
b. staurolite d. quartz f. chlorite
14. The metamorphic rock that would be created by applying heat and pressure to the rock that was the correct answer in #11, above, would be a
a. gneiss c. granite e. marble
b. quartzite d. schist f. phyllite
15. A muddy sandstone is buried along the western margin of South America. Over time, subduction pushes it deeper and deeper into the crust beneath the Andes. Temperatures rise, and eventually it melts. When this hardens and recrystallizes, what rock is going to be the most likely end product?
a. gneiss c. granite e. marble
b. quartzite d. schist f. phyllite
16. The two processes most directly responsible for the thickening and shortening of continental crust, as mountain ranges are created, are
a. normal faulting and weathering c. reverse faulting and folding
b. divergence at the MORRS d. transform faulting and divergence
17. The kind of stress that's most likely to produce folding in rocks is
a. compression c. shearing
b. tension d. ice wedging
18. "Greenstone belts" in the continental shields are often important mining areas, but in the history of the Earth represent ancient
a. island arc systems. c. oceanic crust (ophiolites).
b. segments of the MORRS. d. remnants of continental blocks.
19. Which of the following earthquake predictors is not based on or part of the "dilatency model" for earthquake prediction?
a. strange animal behavior, including pets running away.
b. the tendency for water levels to drop in wells.
c. increased levels of radon gas in well water.
d. an increase, followed by a decrease, in the resistance of the rocks to the passage
of an electrical current.
20. Seismic gaps are
a. areas where there are no known faults although the rocks are under stress.
b. the space between the hanging wall and footwall in a fault zone.
c. lengths of an active fault where no movement has occurred in historic time,
although segments on either side HAVE had earthquake activity.
d. the intervals between giant sea waves that sweep ashore after an earthquake,
as at Banda Aceh, Sumatra, on 26 December, 2004.
Section II: 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; PLEASE RESTRICT YOUR RESPONSES TO THE SPACE PROVIDED. PLEASE ALSO try to 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 75 points possible for this and the following section.
(And PLEASE remember as well that, as promised on the syllabus, I WILL deduct a point each time I see "volcanoe" or "techtonic!")
21. Please identify each of the minerals in Bowen's Reaction Series in the appropriate spaces below (10 points: 1 point each + one bonus point for the first correct answer).
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/
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/
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22. Fill in the following table of igneous rocks with the correct name for each major rock type, formed from the specified magma type in the setting indicated. (6 points: 1 point each)
Magma type | Volcanic rock | Plutonic rock
| |
Felsic (>65% SiO2) | |
| |
| |
Intermediate (55-65% SiO2) | |
| |
| |
Mafic (<55% SiO2) | |
| |
23. Name any five stratovolcanoes from anywhere on Earth. (5 points; 1 point each)
24. What is flocculation, and what is its significance for deposition of sediments in the ocean basins? (5 points)
25. In discussing soil formation, we used a shorthand expression to summarize the five major factors that are critically important in the origins of a soil:
S = ƒ {P, C, B, T, t}
What ARE each of these soil-forming factors? (5 points - 1 pt. each)
P =
C =
B =
T =
t =
26. While driving cross-country through the Rockies in Idaho last summer, you saw
the above section of rock exposed in a canyon wall. You now can appreciate what must have happened, because you recognize and understand the significance of what you saw. (A) What geologic structural feature is depicted here, and (B) what kind of stress would have produced this deformation in the rocks? (10 points)
(A) This is an example of a(n)
(B) It was formed as a product of
24. The Basin and Range Province of the United States is that belt that stretches from the Sierra Nevada in the west to the Rockies in the east, consisting of numerous north-south trending mountain ranges separated by broad valleys. How has this unusual landscape come into being? Include in your discussion the tectonic processes and stresses involved, and what kind of rock deformation has produced this landscape. (10 points)
26. Four factors can vary widely and independently in the creation of metamorphic rocks, which is why metamorphic rocks are so incredibly varied. What ARE these four independent variables? (5 points: 2-1-1-1)
a.
b.
c.
d.
27. On the cover of the WEEKLY WORLD NEWS (a supermarket tabloid), you see a screaming headline that proclaims: "RADIOCARBON DATING OF LAVAS PROVES HUMANS AND DINOSAURS LIVED TOGETHER 1 MILLION B.C.!" What are two major scientific reasons why you would know this alleged "dating" is not possible? (4 points: 2-2)
1.
2.
28. What do scientists believe is the ultimate origin of the volcanic activity, hot springs, etc., that dominate Yellowstone National Park in northwestern Wyoming? (5 points)
Section III: Geography. On the maps on the following pages, please 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: On the map of the world:
Bay of Fundy Greenland
British Columbia Amazon River
Louisiana Nile River
Utah Hudson's Bay
Puget Sound Bermuda
Grade on exam: ______out of 175 possible*.
* If this is below 122, 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.