Geology 141: Autumn, 1997First Hour Exam... Page 1 ...
Geology 141Name ...
Autumn, 1997 6 October, 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.
"Seeing much, suffering much, and studying much, are the three pillars of learning."
- Benjamin Disraeli
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 single element in the Earth's crust, comprising some 45% of the entire crust of the Earth byweight, is
a. silicond. oxygen
b. irone. nickel
c. osmium
2. The oceanic crust of the Earth is about how thick?
a. about 1-2 kmc. about 25-40 kme. about 1200 km
b. about 5-8 kmd. about 40-70 kmf. about 2900 km
3. The mantle of the Earth is believed to be composed mainly of
a. silicate minerals rich in sodium, potassium and aluminum
b. iron, nickel, chromium, and other particularly heavy metals
c. iron and magnesium silicates (at the top) and oxides (at the bottom)
d. non-silicate minerals like calcite, gypsum, apatite and tourmaline
4. The difference between the inner and outer core is that the
a. inner core is solid, while the outer core is liquid.
b. inner core is liquid, while the outer core is solid.
c. inner core is composed of iron and nickel, the outer core is silicates.
d. inner core is dense iron oxides, while the outer part is molten iron.
5. The carbonate minerals are the only non-silicate minerals that are important rock-forming minerals in the Earth's crust, and are characterized by a chemical composition that includes
a. a metal in combination with iron, oxygen and silicon
b. carbon in combination with oxygen and silicon
c. a metal in combination with the element carbon
d. a metal in combination with eight carbon atoms
e. a metal in combination with a CO3 group
6. The critical differences between rocks and minerals is that
a. minerals don't always have to contain silica; rocks always do contain it.
b. rocks can occur anywhere in the Universe; minerals only occur on
Earth.
c. rocks can be man-made; minerals have to be naturally occurring.
d. minerals have to have constant composition and structure, rocks don't.
7. The classification of rocks into three major groups is based on their
a. relative densitiesc. silica content
b. mineral compositiond. mode of origin
8. The viscosity of a magma is a result of all of the following factors EXCEPT
a. volcano typec. dissolved gas content
b. temperatured. silica content
9. The two most common gasses in magmas are
a. steam and carbon dioxidec. hydrogen and oxygen
b. helium and hydrogend. oxygen and nitrogen
10. You are part of an international exploratory team investigating the first photographs of the surface of Jupiter to be taken through its dense and opaque atmosphere. One of the first things you notice is a very steep-sided volcanic cone that rises several thousand meters above the surrounding terrain. Without having any additional information, you can immediately tell that
a. it cannot contain any silicate minerals.
b. it was created by very hot, low-silica magmas.
c. it was produced by very viscous eruptions of some kind of material.
d. it must contain alternating layers of volcanic and plutonic rocks.
11. Some 80% of the world's volcanoes are found
a. in Hawai'i, the Galapagos, Iceland, and other oceanic islands.
b. in the Pacific Northwest, from northern California to Alaska.
c. in Africa, the Himalaya, and the argins of the Persian Gulf.
d. on the margins of the Pacific Ocean.
12. Dikes are
a. igneous intrusions that outcrop over an area greater than 100 km2
b. igneous intrusions that outcrop over an area less than 100 km2
c. tabular intrusive bodies that cut across pre-existing rock units.
d. tabular intrusive bodies that intrude between pre-existing layers.
e. naturally occurring ridges on the coast of the Netherlands (Holland).
13. While mapping the regional geology for a mining company on Sumatra, you have found an unusual area of gabbro that outcrops over an area of about
217 square kilometers. Naming this for the local province, you call this newly discovered geologic unit the
a. Dukong Laccolithc. Dukong Stock
b. Dukong Lithographd. Dukong Batholith
14. The flood basalts of the Columbia Plateau (Northwestern U.S.), central India (the Deccan Traps) and Siberia were all derived from
a. extremely cool, low-silica magmas
b. extremely hot, high-silica magmas
c. extremely cool, low-silica magmas
d. extremely hot, low-silica magmas
15. A typical granite is formed from a magma that in turn is derived from
a. melting of pre-existing low-silica rocks.
b. molten reservoirs of magma deep within the mantle.
c. melting of pre-existing high-silica rocks.
d. molten high-silica magma from the outer core.
16. The minerals at the very top of Bowen's Reaction Series are those that crystallized
a. at very low temperaturesc. at very high temperatures
b. at intermediate temperaturesd. at unknown temperatures
17. The minerals at the very top of Bowen's Reaction Series are those that will be
a. forming in the soil as other minerals (e.g., clays) break down.
b. extremely non-resistant to chemical weathering.
c. moderately resistant to chemical weathering.
d. almost completely resistant to chemical weathering.
18. Typical chemical weathering processes include all of the following except
a. solutionc. hydrolysis
b. baking around an intrusiond. oxidation
19. Of the following minerals, which is the most likely to be a secondary mineral in a soil?
a. clayc. plagioclase
b. biotited. pyroxene
20. The horizon within a soil that will have the highest rate of chemical weathering as well as the most biological activity will be the
a. unaltered parent materialc. B horizon
b. C horizond. A horizon
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. (a) Of what material(s) is the core composed? (3 points) (b) What is the difference between the inner and outer core? (2 points)
(a)
(b)
22. Why is wood not a mineral? (5 points)
23. Name five typical stratovolcanoes (5 points, 1 point each).
24. Identify three potential sources or types of mechanical weathering in rocks. (5 points: 2-2-1)
25. What are the critical differences between mechanical weathering and chemical weathering? (10 points)
26. 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!
On the map of the U.S.:On the map of the world:
New BrunswickAndes Mountains
Lake EriePersian Gulf
IdahoSumatra
ArkansasHawai'i
South CarolinaJapan
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.