Final Exam 1994

GEOL 2082 Final Exam Spring 1999

This 100 minute Final Exam has 50 questions of equal value so allocate your time based on question difficulty. Do not use notes (other than the allowed single-page crib sheet), books, or consult with anyone other than the exam proctor. Good luck on the exam and have a nice summer.

1) Pre-tectonic metamorphism is characterized by:

a. pseudomorphs.

b. recrystallization and grain growth.

c. broken to crushed grains.

d. randomly oriented crystal growth.

e. oriented crystal growth

2) From the Law of Duc de Chaulnes (illustrated at right) it follows that the shallower image is from:

a. the slower ray.

b. the faster ray.

c. the actual object.

d. reflection.

e. polarization

3) The interference figure illustrated at the right: a. has Bxa 2V of 10 degrees

b. has Bxa 2V of 30 degrees

c. has Bxa 2V of 50 degrees

d. has a flash figure

e. has a Bxo figure

4) Trigonal minerals display the following preferred vibration directions when viewed perpendicular to the c-axis. a. X and Y.

b. Y and Z.

c. E only.

d. E and O.

e. O only.

5) From the illustration to the right the following is the liquidus boundary: a. T_Aacross

b. T_Bacross

c. T_Cacross

d. T_A-e-T_B

e. T_Adown-T_Cacross -T_Bup

6) From the general rules of petrography the section illustrated at the right would have the following order of crystallization: a. light, dark, then stippled

b. dark, light, then stippled

c. stippled, light, then dark

d. stippled, dark,then light

e. light, stippled, then dark

7) From the general rules of petrography the section illustrated at the right would have formed under conditions of: a. pre-tectonic metamorphism

b. syn-tectonic metamorphism

c. post-tectonic metamorphism

d. poly-metamorphism

e. iso-metamorphism

8) In the sandstone section illustrated to the right what might account for the texture? a. Variable aeolian and fluvial sources

b. Variable shear

c. Variable compression

d. Variable orientation

e. Variable growth

9) The provenance of a sandstone is: a. the character of its source

b. its transport mechanism

c. the petroleum potential it has

d. its approximate age of uplift

e. its approximate age of deposition

10) Focusing up (lowering the stage) the Becke line ____________ the media with higher index of refraction. a. disperses

b. defines

c. exits

d. enters

e. fluorsces

11) X represents the optic vibration direction with speed. a. zero

b. slowest

c. average

d. intermediate

e. fastest

12) Birefringence of 0.035 would yield a maximum retardation of

______________ in standard sections (0.03 mm thick).

a. 1050 nm

b. 1050 mm

c. 1050 A

d. 1050 (unitless)

e. 1050 10^-6 m

13) For quartz oriented with the c-axis normal to the stage the

__________________ interference figure is seen.

a. retarded

b. symmetric

c. 2V

d. flash

e. centered optic axis

14) When light moves from air to water the ray is bent

__________________ the surface norm.

a. towards

b. away from

c. parallel to

d. perpendicular to

e. inclined to

15) Pleochroism is the result of _______________ absorption. a. dispersive

b. birefringent

c. variable

d. retardative

e. constant

16) In an interference figure the ______________ represents zones of N-S and E-W vibration.

a. isogyres

b. isotopes

c. isochromes

d. isogrades

e. isochlores

17) During dispersion light is bend at angles that are a function of

___________________.

a. thickness

b. wavelength

c. orientation

d. crystal system

e. crystal symmetry

18) The _________________ is the upper magnifying lens of the petrographic microscope.

a. analyzing lens

b. condensing lens

c. objective

d. Bertrand

e. ocular

19) The color yellow has a wavelength of approximately ______________nm. a. 475

b. 575

c. 675

d. 775

e. 875

20) The formula for anorthite is __________________________. a. CaFeSi₂O₆

b. CaMg₂Si₃O₈

c. CaAlSi₃O₈

d. CaAl₂Si₂O₈

e. Al₂Si₃O₉

21) Minerals that might be expected to lineations include _________________ . a. micas

b. chlorites

c. quartz

d. amphiboles

e. olivine

22) The formula CaMgSi₂O₆ represents the mineral ____________ . a. plagioclase

b. biotite

c. hornblende

d. pyroxene

e. olivine

23) Retardation colors readily distinguish _____________ . a. anisotropic from isotropic crystals

b. glass from isotropic crystals

c. glass from other non-crystalline materials

d. opal from glass

e. opal from isotropic crystals

24) The radical Si4O11(OH) represents the __________________ . a. olivines

b. pyroxenes

c. amphiboles

d. tectosilicates

e. feldspars

25) Van der Waals bonds are best illustrated in the mineral _____ . a. olivine

b. talc

c. muscovite

d. biotite

e. plagioclase

26) The common simple twin found in feldspars is ____________ . a. anorthite

b. pericline

c. carlsbad

d. albite

e. plagioclase

27) Sand is a size term for clastic grains in the range: a. transportable by water or wind currents

b. large enough to be insoluable

c. 1 to -1 phi

d. 1 to 0.06 cm

e. 1 to 0.06 mm

28) Two non-equal cleavages of 90 degrees are found in the __________ group. a. feldspars

b. olivines

c. amphiboles

d. pyroxenes

e. chlorites

29) The _______________ are dominated by a single pinacoidal cleavage. a. feldspars

b. olivines

c. pyroxenes

d. amphiboles

e. micas

30) Basalt contains essential augite and __________________. a. plagioclase

b. quartz

c. olivine

d. hornblende

e. microcline

31) Sands may have up to _____________ porosity prior to compaction. a. 2 %

b. 10 %

c. 20 %

d. 40 %

e. 75 %

32) The ________________ is the precusor to a metamorphic rock. a. source

b. protolith

c. premorph

d. regolith

e. protomorph

33) Deformation during metamorphism can be either brittle or ___. a. sheared

b. crystalline

c. isotropic

d. ductile

e. compressional

34) Molecular weights for silicon and magnesium oxides are about 60 and 40 respectively. What are the oxide weight percents for the pyroxene with stoichiometric formula of MgSiO₃? a. About 60% SiO₂ and 40% MgO.

b. About 50% SiO₂ and 50% MgO.

c. About 75% SiO₂ and 25% MgO.

d. About 20% SiO₂ and 20% MgO.

e. About 30% SiO₂ and 15% MgO.

35) What is the stoichiometric formula for a feldspar that is one-third Na and two-thirds K endmembers? a. NaK₂Al₃Si₉O₂₄

b. (Na,K)₃Al₃Si₉O₂₄

c. NaK₂AlSi₃O₈

d. (Na,K)AlSi₃O₈

e. AbOr₂

36) How are orthopyroxenes distinguished from clinopyroxenes? a. The cleavage angles (90/90 versus 120/60 degrees)

b. The 2V angles (high versus low)

c. The indices of refraction (low versus high)

d. The birefringence (low versus high)

e. The extinction angles (symmetric or parallel versus inclined)

37) What criteria are used to estimate the sequence of crystallization in igneous rocks? a. shape and size of the different crystal phases

b. volume amounts of glass and inclusions

c. orientations of the different crystal phases

d. volume amounts of different crystal phases

e. index of refraction and birefringence

38) The most commonly found mineral in the solar system is probably: a. quartz

b. plagioclase

c. pyroxene

d. olivine

e. chlorite

39) Rapid cooling produces crystal morphologies such as. a. pinacoids and pyramids

b. needles and dendrites

c. octahedra

d. tetrahedra

e. euhedra

40) Highly birefringent, high relief, orthorhombic, no cleavage.
a. Augite

b. Enstatite

c. Tremolite

d. Olivine

e. Plagioclase

41) Isotropic, high dispersion, high relief, high price, lasts forever.
a. diamond

b. zircon

c. talc

d. feldspar

e. quartz

42) First order gray-yellow retardation, no cleavages or twinning, may have been picked-up during spring-break. a. quartz

b. plagioclase

c. enstatite

d. olivine

e. tremolite

43) Perfect pinacoid, silky soft.
a. olivine

b. talc

c. muscovite

d. biotite

e. plagioclase

44) Pleochroic in browns, two cleavages at 120 degrees, in granite.
a. biotite

b. tremolite

c. hornblende

d. enstatite

e. augite

45) First order gray-yellow retardation, two unequal cleavages at 90, two different types of twinning: one polysynthetic, one simple both with same composition plane. a. enstatite

b. hornblende

c. quartz

d. plagioclase

e. microcline

46) Non-silicate, three equal cleavages, two images. a. halite

b. calcite

c. fluorite

d. pyrite

e. sodalite

47) From the illustration at the right what is the composition of the opx with positive 2V of 75 degrees and birefringence of 0.21. a. 95% MgSiO₃

b. 82% MgSiO₃

c. 50% MgSiO₃

d. 20% MgSiO₃

e. 05% MgSiO₃

48) The index of refraction of a grain of opx is 1.710 which suggests the following composition(s): a. 50% MgSiO₃

b. 50-60% MgSiO₃

c. 60% MgSiO₃

d. 70% MgSiO₃

e. 60-70% MgSiO₃

49) In unixial minerals the ordinary ray

always vibrates:

a. parallel to the c-axis

b. perpendicular to the c-axis

c. bisecting the a-axis and c-axis

d. perpendicular to the a-axis

e. perpendicular to the b-axis

50) In the illustration to the right the concentric circles represent: a. isopleths

b. melogyres

c. isogyres

d. melatopes

e. isochromes