Department of Geosciences
North Dakota State University
GEOLOGY 105
SELF-TEST SITE


NDSU

Igneous Rocks and Processes Self-Test

Special Instructions:
Using your mouse, click on the one, BEST answer. Upon completion of the exam, click the SUBMIT button, and the exam will be graded for you. You will also have the opportunity to review how well you answered each question.
1. Which one of the following minerals crystallizes out of magma at the lowest temperature?:
olivine
calcium plagioclase feldspar
biotite mica
pyroxene
quartz

2. Mr. Stick wishes to locate an exposure of fine-grained, igneous rock with a mineral content high in calcium plagioclase feldspar, olivine, and pyroxene. Where would Mr. Stick best go?:
Mount St. Helens
Hawaii
a granite quarry near Ortonville, Minnesota
a gabbro outcrop near Duluth, Minnesota
Krakatau

3. Crater Lake, Oregon, represents a lake within a:
vesicle
crater
neck
caldera
sill


4. In Figure 1 (above), Mr. Stick is shown standing next to a volcano. Given its size, this volcano most likely is composed mostly of:
lava
lava flows interbedded with tephra
pyroclastic debris
aa flows
pahoehoe flows

5. Which one of the following word associations is the most correct?:
granite; plutonic rock; basaltic magma
basalt; shield volcano; low silica magma
Iceland; stratovolcano; basaltic magma
Mt. Rainier; cinder cone; gentle eruption
Krakatau; shield volcano; gentle eruption

6. A xenolith is a direct product of:
accretion of ions to a crystal face
extrusive igneous processes
stoping
ionic bonding
fractionation

7. Residents at the base of which one of the following would face the greatest danger of a pyroclastic flow?:
shield volcano
cinder cone
geyser
flood basalts
stratovolcano


8. The pluton shown (above) represents a:
stock
laccolith
sill
batholith
dike

9. Fissure flows:
produce lava floods
cool to form flood basalts
formed the rocks of the Columbia Plateau
generally emit lavas of basaltic composition
ALL OF THE ABOVE ARE TRUE

10. Hollow cavities formed by gas bubbles trapped during the cooling of an igneous rock are:
amygdules
joints
vesicles
bombs
andesites

11. Which one of the following represents a concordant, massive pluton?:
stock
laccolith
batholith
dike
sill

12. Extrusive igneous rocks:
are generally fine-grained
form only from granitic magmas
form only from basaltic magmas
are plutonic
include both granite and basalt

13. Mineralogically, diorite is the equivalent of:
basalt
granite
gabbro
rhyolite
andesite


14. The volcano shown in profile above:
is composed mostly of tephra
emits lavas of high silica content
regularly induces pyroclastic flows
is a composite volcano
NONE OF THE ABOVE STATEMENTS ARE TRUE

15. Devils Tower represents a:
volcanic neck
stock
batholith
dike
sill

16. One would best look for evidence of a chilled margin:
in plutonic rock, near its contact with country rock
in country rock, near its contact with plutonic rock
in the center of a pluton
in the center of country rock
in the center of a plateau basalt flow

17. The settling out of crystals of early-formed minerals from magma was referred to by Bowen as:
reaction
stoping
eruption
fractionation
segregation

18. Ms. Stick picks up a specimen of an igneous rock in a museum and notes that it is phaneritic and rich in quartz. Ms. Stick correctly identifies this rock as:
basalt
diorite
granite
rhyolite
gabbro

19. Rounded pieces of tephra formed from the congealing of lava as it passes through the air are:
ash
cinder cones
bombs
vesicles
pyroclastic flows

20. A lava flow surface that consists of a random mass of jagged blocks is:
pahoehoe
aa
vesicles
amygdules
stoped


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