Deck 5: Igneous Processes and Volcanism

Question 1

-Which of the following best describes the igneous rock depicted in the diagram above?

A) basalt
B) diorite
C) granite
D) rhyolite

Answer 1

B

Question 2

Which igneous rock is the most abundant igneous rock of the crust and underlies virtually all of the floors of the ocean?

A) andesite
B) basalt
C) granite
D) peridotite

Answer 2

B

Question 3

Which of the following properties increases in the direction of the arrows in the diagram below?

A) melting temperature
B) potassium content
C) silica content
D) viscosity

Answer 3

A

Question 4

Mantle plumes that reach the surface form ___________.

A) hot spots
B) mid-ocean ridges
C) island arcs
D) subduction zones

Question 5

What mineral is the most abundant in igneous rocks of intermediate composition?

A) quartz
B) pyroxene
C) plagioclase feldspar

Question 6

Which of the following igneous rocks has the same chemical composition as a diorite?

A) andesite
B) basalt
C) rhyolite

Question 7

Which of the following properties of a magma increases with increasing silica content?

A) melting temperature
B) magnesium content
C) viscosity

Question 8

During crystallization of a magma, plagioclase feldspar becomes richer in

A) magnesium.
B) calcium.
C) sodium.

Question 9

What is the name of an igneous rock that has a mixed texture in which large crystals appear to float in a predominantly finer-grained matrix?

A) porphyry
B) pumice
C) vesicular

Question 10

Which of the following statements about the viscosity of lavas is true?

A) Lava viscosity increases as the silica content of the lava increases.
B) Lava viscosity remains the same as the silica content of the lava increases.
C) Lava viscosity decreases as the silica content of the lava increases.

Question 11

What is the effect of water on rock melting?

A) Water raises the melting temperature of a rock.
B) Water lowers the melting temperature of a rock.
C) Water does not change the melting temperature of a rock.

Question 12

Which of the following would be considered a rapid rate of magma ascent through the Earth's mantle and crust?

A) 0.3 m/yr
B) 10 m/yr
C) 50 m/yr

Question 13

Which statement comparing felsic rocks to mafic rocks is true?

A) Felsic rocks have less silica and more magnesium than mafic rocks.
B) Felsic rocks have less silica and less magnesium than mafic rocks.
C) Felsic rocks have more silica and less magnesium than mafic rocks.
D) Felsic rocks have more silica and more magnesium than mafic rocks.

Question 14

At approximately what temperature do olivine and calcium-rich plagioclase feldspar crystallize from a magma?

A) 300°C
B) 600°C
C) 1200°C
D) 2000°C

Question 15

The process of magmatic differentiation explains how

A) rocks of varying composition can arise from the same parent magma.
B) magma chambers form in the Earth's crust.
C) water lowers the melting temperature of rock.

Question 16

-Which of the following best describes the gray igneous rock depicted in the cross section above?

A) dike
B) lava flow
C) pluton
D) sill

Question 17

Which of the following igneous bodies is a discordant intrusive rock?

A) dike
B) lava flow
C) sill

Question 18

An igneous intrusion whose boundaries lie parallel to the layering in the surrounding country rock is considered to be

A) discordant.
B) concordant.
C) divergent.

Question 19

-What type of lava is most likely to erupt at tectonic setting B?

A) andesite
B) basalt
C) rhyolite
D) All of the above are equally likely.

Question 20

-Which of the following volcanic chains formed at a tectonic setting similar to C?

A) the Aleutian Islands
B) the Hawaiian Islands
C) the Andes Mountains
D) the Mariana Arc

Question 21

-Which of the following volcanic chains formed at a tectonic setting similar to A?

A) the Aleutian Islands
B) the Cascade Range
C) the Andes Mountains
D) the Hawaiian Islands

Question 22

Which of the following mountain chains is made up primarily of volcanoes formed at an ocean-continent subduction zone?

A) Andes
B) Himalayas
C) Mariana Islands

Question 23

-In the basalt sample depicted above, the vesicles (small spherical cavities) most likely formed by ______.

A) the escape of gas bubbles dissolved in the lava during the eruption
B) the weathering and erosion of olivine crystals after the eruption
C) air bubbles entrained in the flow during the eruption
D) vaporization of seawater during underwater eruption

Question 24

Approximately what percentage of Earth's active volcanoes occurs at convergent plate boundaries?

A) 20%
B) 50%
C) 80%

Question 25

What triggers the mantle melting that occurs beneath mid-ocean ridges?

A) a decrease in pressure on rising mantle
B) fluid-induced melting of the mantel
C) frictional heating of the spreading plate
D) heating by deep-mantle hot spots

Question 26

What kind of magma is made from typical extents of partial melting of mantle peridotite?

A) andesitic magma
B) basaltic magma
C) rhyolitic magma
D) felsic magma

Question 27

How much pyroclastic debris was erupted from Yellowstone caldera 600,000 years ago?

A) about 1 cubic kilometer
B) about 10 cubic kilometers
C) about 100 cubic kilometers
D) about 1000 cubic kilometers

Question 28

Which of the following volcanic features is not generally associated with basalt?

A) pahoehoe
B) shield volcanoes
C) volcanic domes

Question 29

What is the term for a large, steep-walled, basin-shaped depression that forms by the collapse of a magma chamber roof after a violent eruption?

A) diatreme
B) caldera
C) lahar

Question 30

Which of the following structures/materials does NOT erupt from a single central vent?

A) cinder cones
B) composite volcanoes
C) flood basalts

Question 31

Which of the following lava types erupts in sheets from fissures to build a lava plateau?

A) andesite
B) basalt
C) rhyolite

Question 32

Volcanic domes are associated with ___ magma.

A) felsic
B) mafic
C) basaltic

Question 33

Which list places the lava types in order of increasing viscosity?

A) basalt, rhyolite, andesite
B) andesite, basalt, rhyolite
C) basalt, andesite, rhyolite
D) rhyolite, basalt, andesite

Question 34

Which kind of magma is least likely to have large catastrophic pyroclastic eruptions?

A) basalt
B) rhyolite
C) andesite
D) All kinds of magma are equally likely to have pyroclastic eruptions.

Question 35

Basalt magmas tend to form narrow and steep conical volcanoes, whereas andesite and rhyolite magmas tend to form broad, gently sloping volcanoes.

Question 36

Approximately how many volcanoes erupt each year?

A) 3
B) 10
C) 50

Question 37

Which of the following states does not have any active volcanoes?

A) Alaska
B) Texas
C) Washington

Question 38

Which of the following volcanic eruptions resulted in the deaths of over 20,000 people?

A) Nevado del Ruiz, Colombia, 1985
B) Mt. Pinatubo, Philippines, 1991
C) Mt. St. Helens, USA, 1980

Question 39

The tallest mountain in the world is which kind of volcanic landform?

A) volcanic dome
B) stratovolcano
C) cinder-cone volcano
D) shield volcano

Question 40

Which of the volcanic structures below is made entirely of pyroclasts?

A) shield volcano
B) stratovolcano
C) cinder-cone volcano
D) volcanic dome

Question 41

Shield volcanoes are built primarily by successive eruptions of which volcanic material?

A) mafic lava flows
B) mafic pyroclasts
C) felsic lava flows
D) felsic pyroclasts

Question 42

Which lava type is least likely to form a volcanic dome?

A) rhyolite
B) dacite
C) andesite
D) basalt

Question 43

Which is a volcanic landform built up from alternating lava flows and beds of pyroclasts?

A) shield volcano
B) stratovolcano
C) cinder-cone volcano
D) basalt plateau

Question 44

Which statement regarding fissure eruptions is true?

A) Fissure eruptions most commonly erupt felsic magmas.
B) Fissure eruptions result in the formation of shield volcanoes.
C) Fissure eruptions are relatively common at mid-ocean ridges.
D) Overall, relatively little magma has been erupted via fissure eruptions.

Question 45

The Columbia River flood basalts are the only known instance of flood-basalt volcanism.

Question 46

Which of the volcanic eruption-related hazards listed below has caused the fewest deaths overall?

A) pyroclastic flows
B) lahars
C) tsunamis
D) lava flows

Question 47

Which of the U.S. volcanoes listed below is considered to pose the greatest risk to the population?

A) Mt. St. Helens volcano
B) Mt. Rainier volcano
C) Kilauea volcano
D) Mauna Loa volcano

Question 48

What is the plate tectonic environment that has caused the formation of the volcanoes of the Cascade Range in Oregon and Washington States (including Mt. Rainier, Mt. St. Helens)?

A) Continental rifting environment
B) Transform fault environment
C) Subduction zone environment
D) Mantle hotspot environment

Question 49

Which of the following volcanic eruptions was predicted by geoscientists, enabling evacuation of the area?

A) 1994 Papua New Guinea eruptions
B) 1980 Mt. St. Helens eruption
C) 1991 Mt. Pinatubo eruption
D) All of these

Question 50

Flank collapse of a volcano, though potentially very hazardous, occurs only about once every million years.

Question 51

Hawaii and Alaska are the only U.S. states with historically active volcanoes.