Deck 8: Volcanoes and Plutons

Question 1

A geologist would expect to find what type of magma composition at spreading ridges because it has a lower density?   _________________

A) Granite
B) Peridotite
C) Andesite
D) Basalt

Answer 1

D

Question 2

If a rock has mineral crystals melt in a magma chamber, how does this change the volume of the magma? ______

A) Reduces the volume of the magma because the atoms become disordered and move freely
B) Increases the volume of the magma because the atoms become disordered and move freely
C) There is no change in the volume of magma when the atoms become disordered and move freely
D) None of the above

Answer 2

B

Question 3

Which type of intrusive igneous body existed to form the Sierra Nevada Range?

Answer 3

batholith

Question 4

Geologists hypothesize that Earth's first crust was composed of ____________________ because it is very low in silica and formed when the Earth's interior was much _______ than it is today.

Question 5

The most common type of oceanic igneous rock is _____________ because it comes from mid-oceanic ridges while the most come type of continental igneous rock is _________________ because it makes up the continents.

Question 6

Swarms of ____________________ are one of the short-term indicators that a volcanic eruption is about to occur.

Question 7

If large amounts of ash dust and aerosols are released from a volcanic eruption, this will reflect sunlight and cause what type of temperature change for Earth's climate? _____________

Question 8

If you see a large circular depression in the ground in a volcanic region, what specific type of feature is it?

Question 9

An increase in ____________________ and/or ____________________ will melt a hot rock.

Question 10

Generally, as the concentration of _______ decreases in magma rocks, its melting point temperature increases.

A) Calcium
B) Pyroxene
C) Silica
D) None of the above

Question 11

Basaltic magma commonly remains ____________________ as it rises to the surface, whereas granitic magma usually ____________________ within the crust.

Question 12

If you saw an igneous pluton in the field that had oozed between rock layers, what did you see?

Question 13

Generally, a mixture of two or more minerals will begin to melt at a temperature ____________________ (lower/higher) than the melting point of any one of the minerals in its pure state.

Question 14

If you find a piece of lava that solidified before the gas had escapes, the bubbles are preserved as holes in this rock are called ____________________.

Question 15

If magma experiences an increase in pressure, how does this affect magma? ________________

Question 16

Nearly all of Earth's oceanic crust is created by ____________.

A) hot spots
B) spreading centers
C) subduction zones
D) mantle plumes

Question 17

Lava and rock fragments commonly erupt from a(n) ____________________ located in the crater of a volcano.

Question 18

Granitic magma has a lower melting temperature compared to basaltic magma because it contains a higher percentage of which specific mineral? __________________

A) Calcium
B) Pyroxene
C) Silica
D) None of the above

Question 19

The Yellowstone Volcano results from a shallow ____________________ that lies far from the nearest plate boundary similar to Hawaii which is in the middle of the Pacific Plate.

Question 20

If you saw an ash-flow tuff or a caldera in the field, what type of eruption would have likely caused both to form?

Question 21

What is the most important factor in producing melting in a subduction zone because higher water percentages of it allows the magma to melt at a lower temperature?

A) The addition of water
B) An increase in temperature
C) A decrease in pressure
D) Frictional heating

Question 22

A composite cone ____.

A) forms by repeated lava flows and pyroclastic eruptions over a long time
B) is usually active for only a short time
C) forms by pyroclastic eruptions only
D) forms in a single, cataclysmic event

Question 23

If you saw basaltic lava in Hawaii that had a surface which was smooth ropy surface, what specific type of lava would this be called?

A) pahoehoe
B) aa
C) granitic
D) pyroclastic

Question 24

A shield volcano is produced by ____.

A) basaltic magma that oozes like water over Earth's surface
B) fluid basaltic magma that builds a gently sloping mountain
C) rising water-saturated granitic magma
D) rising relatively dry granitic magma

Question 25

Oceanic crust is typically composed of ____.

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

Question 26

What is the process in which peridotite melts and forms basalt that is more silica rich?

A) high pressure melting
B) partial melting
C) geothermal melting
D) friction melting

Question 27

If pure olivine melts at 1890°C and pure pyroxene melts at 1390°C, and peridotite is a mixture of the two, which of the following is a likely melting temperature for peridotite?

A) 1890° C
B) 1270° C
C) 1390° C
D) 2100° C

Question 28

Welded tuff and ash-flow tuff deposits derive from what specific type of eruption?

A) Pahoehoe
B) Pyroclastic
C) aa
D) Lahar

Question 29

Which process causes crystallization of magma to form igneous rock?

A) The addition of water
B) An increase of pressure
C) An increase of temperature
D) A decrease of pressure

Question 30

Magma with a high-water content has a greater tendency to _________ in the crust as compared with magma with a lower water content.

A) Solidify
B) remain liquid
C) metamorphose
D) spread out

Question 31

____ joints are regularly spaced cracks that form in lava flows and grow downward.

A) Vesicle
B) Ash
C) Columnar
D) Cinder

Question 32

If you visit the Hawaiian Islands and go see Kilauea, what specific type of volcano would it be called? _________

A) composite
B) shield
C) basalt plateau
D) cinder cone

Question 33

If you saw a plutonic igneous feature cuts across rocks in the field, what specific feature would this be?

A) batholith
B) sill
C) dike
D) stock

Question 34

Continental crust is typically composed of ____.

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

Question 35

Which list correctly orders magma rock going from highest silica and water content to lowest?

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

Question 36

The oldest zircons from Australian sandstone were formed when the Earth formed it oldest continental crust and must have derived from what type of rock?

A) Basalt
B) Peridotite
C) Granite
D) Rhyolite

Question 37

If a volcano has a gas-charged eruption, what type of feature would form if the magma chamber collapses into the space that the magma had filled? __________________

A) ash-flow tuff
B) lahar
C) caldera
D) impact crater

Question 38

If you are in Hawaii and see lava that has a jagged, broken surface, what is the specific name of the lava?

A) Pahoehoe
B) aa
C) Rough
D) Pyroclastic

Question 39

If a geologist found an igneous pluton at the surface and it was 40 km2, what type of feature would it be?

A) batholith
B) volcanic neck
C) dike
D) stock

Question 40

If you were a volcanologist, which type of magma would you expect to erupt the most violently because it has the highest percentage of silica content?

A) Basaltic
B) Andesitic
C) Icelandic
D) Granitic

Question 41

If a volcanic eruption releases large amounts of aerosols into the atmosphere, they will reflect sunlight back to space and will cause a warming effect on Earth's climate for months or years.

Question 42

If large concentrations of sulfur dioxide molecules are released during volcanic eruptions like Pinatubu of 1991, this can reflect sunlight in the upper atmosphere and cause atmospheric cooling for Earth's climate.

Question 43

A sill igneous intrusion forms when magma is injected into a fracture that cuts across rock layers.

Question 44

Mount Vesuvius is an example of a ____ volcano that is a steep-sided volcano formed by an alternating series of lava flows and pyroclastic deposits and marked by repeated eruption.

A) cinder cone
B) stratovolcano
C) composite
D) shield

Question 45

The eruption of Mount Helens in 1980 produced such great ash and sulfur clouds that Earth's surface temperatures were cooler for the following two years.

Question 46

Volcanic ____ consist(s) of the smallest particles formed when liquid magma explodes into the air.

A) cinders
B) air-fall tuff
C) welded tuff
D) ash

Question 47

If global warming reduced the amount of precipitation in the Yellowstone region, the confining pressure on superheated groundwater would decrease and may lead to more frequent hydrothermal explosions.

Question 48

Regional predictions based on the concentration of volcanoes in an area can be used to determine the intensity of a particular eruption because each eruption will contain the same type and volume of magma.

Question 49

____ explosions occur in regions in which the groundwater has been heated past the boiling point.

A) Hydrothermal
B) Pyroclastic
C) Air-fall tuff
D) Caldera

Question 50

If you have two rocks and one contains small amounts of water, it will generally melt at a lower temperature than an otherwise identical dry rock.

Question 51

The process of partial melting helped produce silica-rich continents because the source of the magma evolved from silica-poor mantle.

Question 52

If you are looking at a volcano and its sides gently slope from the vent at angles between 6° and 12°, you are looking at a cinder cone volcano.

Question 53

Yellowstone Park is an example of three overlapping ____.

A) calderas
B) mantle plumes
C) shield volcanoes
D) lava plateaus

Question 54

Mauna Kea Volcano in Hawaii, measured from its true base at the bottom of the ocean, is the tallest mountain in the world and is classified as a shield volcano.

Question 55

Basaltic magma has longer chains of silicate tetrahedra than granitic magma allowing it to increase in velocity and this would cause basaltic volcanoes to erupt more violently than volcanoes with granite magma.

Question 56

A cinder cone volcanic eruption is typically active for only a short period of time because once the gas escapes, the driving force behind the eruption is removed unlike composite volcanoes which represent repetitive eruptions.

Question 57

Magma in the asthenosphere is primarily granite in composition because the magma is high in silica in the athenosphere.

Question 58

The Columbia River plateau in the northwestern United States is an example of a(n) ____, in which lava covers the landscape like a flood.

A) composite flow
B) flood basalt
C) ash-flow tuff
D) welded tuff

Question 59

If scientists can show that seismic waves rapidly slow down allowing S waves not to register beneath Mount Vesuvius, this means molten magma still exists at that depth and could erupt again in the future.

Question 60

Magma forms abundantly at transform boundaries because one plate is subducting into the mantle allowing for the formation of magma chambers.

Question 61

Explain how a batholith can contain smaller plutons within its system and provide an example of this.

Question 62

Identify and describe the differences among the three tectonic environments in which magma is formed.

Question 63

Explain how water impacts the temperature at which magma solidifies.

Question 64

Explain how granite continental crust originally came from peridotitic lava.

Question 65

Explain why and what type of lava is created at rift zones.

Question 66

Explain how peridotite magma turns into basaltic magma and how the two magma types differ.

Question 67

Explain how the asthenosphere has both molten rock and solid rock.

Question 68

Explain what the differences are between aa and pahoehoe basaltic lava and identify what their magma chemistry is.

Question 69

Explain how temperature is an important indicator of the chemistry of magma.

Question 70

Explain what causes some volcanic rocks to contain holes called vesicles.

Question 71

Explain how batholiths can cover more than 100 km² in diameter.

Question 72

Explain why granite magma is more viscous than basaltic magma.

Question 73

Explain how igneous rocks of intermediate composition are formed from basaltic magma.

Question 74

Explain how fissure eruptions can create flood basalts.

Question 75

Explain how scientists have determined the origination of the Earth's first continental crust.

Question 76

Explain two ways basaltic magma is deposited on the Earth's surface.

Question 77

Explain how the partial melting of peridotite yields basalt magma.

Question 78

Explain how tectonic accretion led to the formation of the earliest continental crust.

Question 79

Explain how the melting of minerals increases the size of a magma chamber.