Geol 15 Exam II: Minerals, Igneous Rocks, Volcanoes

Geol 15 Exam II: Minerals, Igneous Rocks, Volcanoes

1. Where is new oceanic crust produced, and what is the process called?

a. fracture zones, seafloor spreading b. mid ocean ridge, seafloor spreading c. arc volcanoes, subduction d. arc volcanoes, seafloor spreading 2. What causes magmas (i.e. volcanic activity)

to occur at subduction zone settings? a. melting of ocean lithosphere due to heat b. melting of upper mantle due to heat c. melting of upper mantle due to dehydration

of ocean plate 3. What is the difference between island arc

and continental arc (Japanese type vs. Andean type)?

a. one is a divergent margin, the other is convergent

b. one is a transform margin, the other is divergent

c. one is ocean-ocean convergent, the other is ocean-continent convergent

d. both a and c 4. The Cascade volcanoes Shasta and Lassen

Peak are the result of the subduction of which plate?

a. Juan de Fuca plate b. Cocos plate c. Gorda plate d. Nazca plate 5. The San Andreas is a transform boundary

between which two tectonic plates? a. Pacific and Farallon b. North American and Pacific c. North American and Gorda d. North American and Farallon 6. What is the most famous chain of hot spot

related islands, and where is the hot spot now?

a. Japan, Tokyo b. Andes, Peru c. Hawaii, Maui d. Hawaii, Kauai e. Hawaii, Hawaii 7. The building blocks of rocks are what? a. chemical elements b. rock fragments c. atoms d. minerals

8. Which of the following is NOT on of the four-part definition of a mineral.

a. naturally occurring b. inorganic solid c. amorphous chemical structure d. crystalline internal arrangement of atoms e. specific or slightly variable chemical

composition 9. What is the mineral names of the chemical

composition silica dioxide a. halite b. quartz c. calcite d. fluorite 10. What is the mineral name of the chemical

composition calcium carbonate. a. halite b. quartz c. calcite d. fluroite 11. Is volcanic glass crystalline? a. yes b. no 12. On Mohs hardness scale, what is the

hardness of a knife blade. a. 4.5 b. 3.5 c. 7.5 d. 5.5 13. What are the two primary types of luster? a. metallic, vitreous b. metallic, non metallic c. metallic, brass d. vitreous, glassy 14. What do all igneous rocks have in common? a. cool from magma b. cool from metamorphic rock c. erupt from volcanoes 15. Which of the following is NOT one of the

process of lithification? a. compaction b. cool from magma c. cementation d. burial 16. Igneous rocks are classified based

principally on what two characteristics? a. volcanic, plutonic b. phaneritic, aphanitic c. texture, composition

Geol 15 Exam II: Minerals, Igneous Rocks, Volcanoes

17. Grain sizes of volcanic are _____and plutonic rocks are ____.

a. coarse, fine b. fine, coarse 18. What is a batholith? a. small plutonic body b. 40 or less plutonic bodies c. 40 or more plutonic bodies d. 40 or more lava extrusions 19. What does porphyritic texture tell you about

the cooling history of the rock? a. fast cooling b. slow cooling c. two stage cooling history 20. Which of the following is NOT a “light” or

felsic principal rock-forming silicate. a. olivine b. quartz c. K- fledspar d. muscovite 21. Peridotite is important for at least two

reasons. What are they? a. melts to produce basaltic magmas b. rock that comprises upper mantle c. California State rock d. Both a and b e. Both a and c 22. What is the most abundant type of volcanic

rock on earth? a. andesite b. granite c. serpentinite d. basalt Volcanology 23. The California Cascade volcanoes are a

result of the subduction of what oceanic plate?

A) Gorda Plate B) Juan de Fuca Plate C) Farallon Plate D) Cocos Plate 24. Volcanic rocks are typically ___________

and plutonic rocks are typically ______________.

A) coarse grained, fine grained B) fine grained, coarse grained C) black, light D) mafic, felsic

25. All igneous rocks share this common characteristic.

A) all derived from a melt (magma) B) erupt out of a volcano C) cool and pond in the crust D) form at convergent boundaries 26. What is the most abundant type of volcanic

rock on earth? A) rhyolite B) andesite C) dacite D) basalt 27. An “active” volcano has erupted in the past A) 200 years to 2000 years B) 2000 years to 1.6 million years C) past 2000 years D) greater than 1.6 million years 28. A potentially active volcano is one that has

erupted in ______________. A) past 2000 years B) past 2000 years to 1.6 million years C) greater than 1.6 million years D) 200 years to 2000 years 29. Approximately how many active vents are

there in California? A) 20 vents B) 500 vents C) 50 vents 30. The relationship between silica content,

polymerization, and viscosity is ______? A) more silica, more polymerization, more

viscosity B) less silica, more polymerization, more

viscosity C) more silica, less polymerization, less

viscosity D) no relationship 31. What drives volcanic explosions? A) gas content alone B) gas content and high FeO, MgO C) gas content and high silica D) gas content and low silica 32. Mafic volcanoes have ______ lava and

_______ explosive eruptions. A) viscous, highly B) fluid, minor C) viscous, minor D) fluid, highly

Geol 15 Exam II: Minerals, Igneous Rocks, Volcanoes

33. Silicic volcanoes have _____ lava and ______ explosive eruptions.

A) viscous, minor B) fluid, highly C) fluid, minor D) viscous, highly 34. Why is Mt. Shasta high in elevation and the

Modoc Plateau relatively flat? A) Mt. Shasta is a shield volcano and the

Modoc Plateau is rhyolitic in composition B) Mt. Shast is a stratovolcano and the Modoc

Plateau is flood basalt province C) Mt. Shasta is a lava dome and the Modoc

Plateau is a caldera D) Mt. Shasta is a cinder cone and the Modoc

Plateau is a flood basalt province

35. What is the relationship between silica

content and the eruptive styles of magmas? A) the more silica, the less gas, the more

explosive eruption B) the less silica, the less gas, the more

explosive eruption C) the more silica, the more gas, the more

explosive the eruption D) the more silica, the more gas, the less

explosive the eruption

36. What are the two ways felsic magmas may form (discussed in lecture)? 37. What is the slope angle of the volcano depicted below? ______________ 38. What type of volcano is depicted below?______________________

Geol 15 Exam II: Minerals, Igneous Rocks, Volcanoes

39. On the table below, place granite, gabbro, andesite, diorite, basalt, and rhyolite in their correct

positions. Under texture, label whether fine-grained or coarse-grained rocks. (8 pts) Felsic/Silicic Intermediate Mafic Texture Volcanic

Plutonic