EXAMPLE!!!!!

EARTH AND PLANETARY SCIENCES 101

SECTION 004 (TTh12:30) Instructor: John Geissman

FIRST HOURLY EXAMINATION Thursday, February 18, 1999

Name:____________________________ SSN:_________________________

THIS EXAM IS PRINTED DOUBLE-SIDED. SORRY FOR ANY INCONVENIENCE. READ THE INSTRUCTIONS FOR EACH OF THE FOUR SECTIONS CAREFULLY. Please DRAW to my ATTENTION of that of another proctor ANY QUESTIONS YOU MAY HAVE. You have until 1:45 to complete this exam.

I. Short Answer Questions:

1. What process(es) led to the differentiation of the earth? ( 4 points).

2. The result of the differentiation of the Earth is a “layered”, interally heterogeneous sphere; the layers are depicted below. For each of the six layers depicted, give their names and a rough approximation of their composition (6 points).

a. layer_____________ composition_____________________

b. layer _____________ composition __________________

c. layer _____________ composition __________________

d. layer ______________ composition ________________

e. layer ______________ composition ___________________

f. layer _______________ composition ___________________

3. What layers (or parts of layers) form the “plates” (lithosphere) in plate tectonics? (3 points)

4. There are three different (general) types of plate boundaries. What are they? For each, give an example, and describe how each fits into the fundamental basis of plate tectonics (6 points).

a. _____________________ example: _____________________________

role in plate tectonics: __________________________________________________

b. _____________________ example: _______________________________________

role in plate tectonics: _________________________________________________________

c. _____________________ example: ________________________________________

role in plate tectonics: ________________________________________________________

5. What is a mineral? (2 points)

6. Name three minerals, including at least one silicate mineral, and give their formulas: (3 points)

Name: _______________________ formula: ___________________________

7. What is the essential “building block” of all silicate minerals? What is its net electric charge? A particularly important mineral in the mantle of our planet has the formula (Fe,Mg)2SiO4. How are the silicate building blocks arranged in this particular mineral, to be consistent with its formula? (3 points)

8. In the crust of Earth, what is the most important group of silicate minerals? Why? (2 points)

9. Briefly define the three types of rocks: (6 points)

Name: ______________________ definition: ____________________________________

Name: ______________________ definition: _____________________________________

10. How do each of the three types of rocks “fit” into the rock cycle? In other words, what process might allow one type of rock to be changed into another? (3 points)

11. The terms mafic and felsic have been used to describe the two general compositional characters of igneous rocks. Define each term, give names for rocks represented by these compositions, and compare and contrast the physical properties of these magmas. (9 points)

Mafic Felsic

a. definition:

b. intrusive rock name

c. extrusive rock name

d. viscosity

e. temperature

f. color

g. silica content

h. type of volcano

i. important silicate minerals

12. What are the two types of weathering and what are some differences between them? (4 points)

13. What are the essential components of any soil profile? What is the origin of calcium carbonate in pedocal type soils? (4 points)

II. Multiple Choice Questions (two points each)

1. Which of the following volcanic chains is representative of a plate tectonic setting where oceanic lithosphere is subducted beneath oceanic lithosphere,

a. Cascade Range

b. Andes Mountains

c. Hawaiian Islands

d. Aleutians

2. At a mid-ocean ridge (spreading center) environment, what type of lava is most likely to erupt?

a. andesite

b. basalt

c. ultramafic composition

d. rhyolite

e. none of the above

3. In what kind of plate tectonic setting did Mt. St. Helens form?

a. mid-ocean ridge

b. subduction zone, with oceanic lithosphere descending beneath the margin of continental lithosphere

c. subduction zone, with continental lithosphere descending beneath the margin of oceanic lithosphere

d. subduction zone, with oceanic lithosphere descending beneath the margin of oceanic lithosphere

e. none of the above.

4. In Bowen’s reaction series, what mineral is the first to form (at the highest temperatures) in the discontinuous branch of the series?

a. amphibole

b. quartz

c. potassium feldspar

d. olivine

5. What mineral forms at lowest temperatures in the continous branck of the series?

a. biotite

b. sodium feldspar

c. olivine

d. quartz

6. Of the following minerals, which is typically one of the last to form in a solidifying igneous melt?

a. olivine

b. amphibole

c. calcium feldspar

d. quartz

7. What factors could lead to an increase in weathering rate?

a. increasing rainfall

b. increasing temperature

c. increasing organic activity

d. greater density of fractures in parent materials

e. all of the above

8. In the chemical weathering of potassium feldspar (orthoclase), which of the following chemical species is not produced?

a. Al₂Si₂O₅(OH)₄ (kaolinite, a clay mineral)

b. K⁺, potassium ion in solution

c. SiO₂, dissolved silica

d. H₂O, water

9. In a hot, relatively dry climate like that of the southwestern United States, what type of soils are expected to form?

a. laterites

b. pedocals

c. pedalfers

d. evaporites

e. none of the above

10. In the production of a soil

a. climate plays no role, whatsoever

b. the development of a long-term, stable surface is a requirement

c. parent rock of the C horizon has no control on the type of soil produced

d. the development of both the A and B horizons always proceeds at the same rate

e. the B horizon represents the zone where most of the chemical leaching of elements occurs.

11. In the silicate tetrahedron, the silicon atom (with tendency to become a cation) has a coordination number of (or is surrounded by how many oxygen atoms.

(a) 2, (b) 3, (c) 4, (d) 6, (e) 12.

12. Which of the following statements about a scientific theory is not true?

(a) it is an explanation for a particular natural phenomenon

(b) it has a large body of supporting evidence

(d) it is testable

(e) it assumes no pre-conceived notion or “faith” in one explanation over another for a particular natural phenomenon

(e) none of the above

13. The velocity of lithosphere plate motion (i.e. the rate of formation of oceanic lithosphere at mid-ocean ridges) is

(a) typically is on the order of kilometers per year

(b) cannot be measured

( c) is comparable to the rate at which your fingernails grow

(d) typically on the order of centimeters per million years.

14. What fundamental process is believed to be responsible for plate motion?

(a) subduction

(b) hot spot activity

(d) convection cells in the mantle

(e) density differences

15. To which of the following groups do most minerals in the earth's crust belong?

(a) carbonates

(b) oxides

(d) halides

(e) native elements

16. To emphasize the concept of plate tectonics, I showed a simple experiment where a layer of relatively cold, solid material, of relatively high density, is carefully placed above a material in a liquid or partially liquid state. The liquid or partially liquid state corresponds to

(a) the asthenosphere, which lies beneath the lithosphere

(b) the asthenosphere, which is composed primarily of silicic rocks

(d) the crust

(e) all of the above