Ch.4 + CH.12

Granite is a coarse-grained igneous rock with about ________% SiO2. 10 30 50 70

70

volcanic domes are associated with ________ magma.

mafic

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? porphyry pumice vesicular pyroclastic

poryphry

Which of the following properties of a magma increases with increasing silica content? melting temperature magnesium content viscosity density

viscosity

What happens to temperature with increasing depth in the Earth? Temperature increases with depth at the same rate everywhere. Temperature decreases with depth at the same rate everywhere. Temperature increases faster with depth where Earth's crust is being stretched. Temperature increases faster with depth in tectonically stable regions.

Temperature increases faster with depth where Earth's crust is being stretched.

gneous rocks with crystals too small to be seen without a microscope are: coarse grained. fine grained. glassy. vesicular.

fine grained

Approximately how many volcanoes erupt each year? A. 3 B. 10 C. 50 D. 500

50

Which of the following would be considered a rapid rate of magma ascent through the Earth's mantle and crust? 0.3 m/yr 10 m/yr 50 m/yr 50 km/yr

50 m/yr

Approximately what percentage of Earth's active volcanoes occurs at convergent plate boundaries? A. 20% B. 50% C. 80% D. 10%

80%

What is the eruption temperature of rhyolitic lava?

800-1000°C

Which of the following is not involved in classifying igneous rocks? texture group of minerals making up rock chemical composition of the rock All of the above are involved.

All of the above are involved.

Why could the early geologists in western Europe not directly observe the formation of coarse-grained igneous rocks? There weren't any igneous rocks in Europe. Coarse-grained igneous rocks form deep in the crust and are inaccessible when forming. Coarse-grained igneous rocks formed at the bottoms of deep lakes and weren't visible when forming. It was too dangerous to get close to exploding volcanoes where coarse-grained igneous rocks were forming.

Coarse-grained igneous rocks form deep in the crust and are inaccessible when forming.

Mafic igneous minerals are all rich in: Fe, Mg. Na, K. Al, Na. K, Al.

Fe,Mg

Which of the following locations is composed of intraplate volcanoes? A. Iceland B. Cascade Range C. Hawaiian Islands D. Indonesia

Hawaiian islands

What is one indication that aseismic ridges are not plate boundary volcanic ridges? A. Islands of ridge are progressively older in the direction of plate movement. B. Ridge volcanoes are all active. C. Rocks of volcanoes are primarily andesitic. D. Volcanic rocks are primarily rhyolitic.

Islands of ridge are progressively older in the direction of plate movement.

What is a possible explanation for eruptions that form large igneous provinces? A. Large meteorite impacts crack the lithosphere. B. They are locations of newly developed mantle plumes. C. Reversals of convergent margins. D. They occur along transform faults.

Large meteorite impacts crack the lithosphere.

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

Lava viscosity increases as the silica content of the lava increases.

During crystallization of a magma, plagioclase feldspar becomes richer in: magnesium. calcium. sodium. iron.

Magnesium

What is the largest volcano on Earth? A. Mauna Loa, Hawaii B. Mt. Rainier, Washington C. Mount Unzen, Japan D. Mont Pinatubo, Philippines

Mauna Loa, Hawaii

Which of the following volcanoes is NOT a composite volcano (stratovolcano)?

Mauna Loa, Hawaii

Which of the following statements is true? Molten rock is less dense than solid rock. Molten rock is denser than solid rock. Molten rock and solid rock have the same density. There is no way to tell which is denser

Molten rock is less dense than solid rock.

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. Mount St. Helens, USA, 1980 D. Mauna Loa, USA, 2002

Nevado del Ruiz

Felsic igneous rocks are rich in: FeO. MgO. SiO2. CaO.

SiO2

The basis for the classification of igneous rocks based on chemical composition is __________ content. FeO Al2O3 MgO SiO2

SiO2

Which of the following states does NOT have any active volcanoes? A. Alaska B. Texas C. Washington D. Hawaii

Texas

What is the difference between a volcanic tuff and a volcanic breccia?

Tuffs are made of small volcanic fragments (pyroclasts) and breccias are formed from larger volcanic fragments.

What is the effect of water on rock melting? Water raises the melting temperature of a rock. Water lowers the melting temperature of a rock. Water does not change the melting temperature of a rock. Water raises or lowers melting temperatures of different rock compositions.

Water lowers the melting temperature of a rock.

The location in North America interpreted to lie over a hot spot is: A. San Francisco. B. Mt. Rainier. C. Alaska at the eastern end of the Aleutian Islands. D. Yellowstone Park.

Yellowstone park

`Pumice is: a frothy mass of volcanic glass. identical to obsidian. an intrusive fine-grained igneous rock. a basaltic intrusive igneous rock.

a frothy mass of volcanic glass.

The sequence of events from melting through eruption is referred to as _________. A. a volcanic geosystem B. the melting game C. magma production D. the asthenosphere

a volcanic geosystem

Ring of Fire" volcanoes occur: A. along mid-ocean ridges. B. as within-plate volcanoes. C. above subduction zones. D. along rift zones.

above subduction zones.

Which of the following causes a decrease in melting temperature of rocks? decreasing pressure increasing water content more Felsic composition all of the above

all of the above

How did geologists discover the relationship between cooling rate and crystal size? observation of volcanic flows erupting and solidifying laboratory cooling of magmas study of granitic rocks and surrounding sedimentary rocks all of the above

all the above

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 D. Appalachians

andes

Intermediate igneous volcanic rock is: basalt. granite. gabbro. andesite.

andesite

Which of the following igneous rocks has the same chemical composition as a diorite? andesite basalt rhyolite gabbro

andesite

Subduction zone volcanoes produce rock of dominantly _____ composition. A. granitic B. rhyolitic C. basaltic D. andesitic

andesitic

The largest pyroclastic deposits on Earth are: A. lava domes. B. flood basalts. C. ash flow deposits. D. shield volcanoes.

ash flow deposits

The ___________ is the main source of magma for the production of igneous rocks. A. lithosphere B. asthenosphere C. crust D. core

asthenosphere

Almost the entire ocean floor is comprised of which igneous rock? granite diorite rhyolite basalt

basalt

In which of the following igneous rocks would you be most likely to find the mineral (Mg,Fe)2SiO4? andesite basalt granite rhyolite

basalt

Which of the following lava types erupts in sheets from fissures to build a lava plateau? A. andesite B. basalt C. rhyolite D. granitic

basalt

Which of the following type(s) of rock(s) crystallize at the highest temperature? basalt granite hydrothermal veins rhyolite

basalt

Which of the following sequences of volcanic rocks are in the correct order of increasing silica content?

basalt, andesite, rhyolite

The three major rock products of erupted lavas are: A. basalt, granite, and rhyolite. B. basalt, rhyolite, and andesite. C. gabbro, andesite, and rhyolite. D. gabbro, andesite, and granite.

basalt, rhyolite, and andesite.

Axial volcanoes of mid-ocean ridges are: A. basaltic. B. andesitic. C. granitic. D. rhyolitic.

basaltic

Basaltic pillow lavas are a strong indicator of: A. intrusive crystallization of magma. B. lava that fountained into the air. C. basaltic lava that erupted into water. D. the eruption of already-solid volcanic glass.

basaltic lava that erupted into water.

Great, irregular masses of coarse-grained igneous rock (the largest pluton): xenoliths. batholiths. sills. dikes.

batholiths.

Which of the following melting processes is important beneath mid-ocean ridges? decompression melting fluid-induced melting both decompression melting and fluid-induced melting neither decompression nor fluid-induced melting

both decompression melting

Fractional crystallization is the process: by which crystals formed in a cooling magma are removed from the remaining magma. by which magma is split into intrusive and extrusive as it cools. by which one-quarter of the magma crystallizes as each of four minerals. by which only a fraction of each magma ever crystallizes.

by which crystals formed in a cooling magma are removed from the remaining magma.

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?

caldera

An igneous intrusion whose boundaries lie parallel to the layering in the surrounding country rock is considered to be: discordant. concordant. divergent. convective.

concordant

Mantle plumes are thought to originate at the ___ boundary. A. crust-mantle B. core-mantle C. convergent plate D. divergent

core-mantle

Which of the following best describes a gabbro? dark-colored, coarse-grained igneous rock dark-colored, fine-grained igneous rock light-colored, coarse-grained igneous rock light-colored, fine-grained igneous rock

dark-colored, coarse-grained igneous rock

Shiprock in New Mexico is an example of a: A. diatreme. B. shield volcano. C. caldera. D. cinder cone.

diatreme

Which of the following igneous bodies is a discordant intrusive rock? dike lava flow sill pyroclastics

dike

If hot spots remain fixed in the mantle, then volcanic chains formed at these spots can be used to indicate: A. how old the plate is. B. direction and rate of plate movement. C. what makes plates move. D. where major earthquakes will occur.

direction and rate of plate movement.

What component of magma is required to cause violent volcanic eruptions? A. dissolved gases B. iron C. calcium D. aluminum

dissolved gases

Pyroclastic rocks are a variety of: intrusive igneous. extrusive volcanic flows. extrusive explosive volcanics. metamorphic rocks.

extrusive volcanic flows.

Which of the following structures/materials do NOT erupt from a single central vent? A. cinder cones B. composite volcanoes C. flood basalts D. shield volcanoes

flood basalts

Large igneous provinces like the Kerguelen Plateau are formed from the successive eruptions of: A. pyroclastic flows. B. andesitic lava. C. flood basalts. D. rhyolitic flows.

flood basalts.

Magmas in subduction zones are produced primarily by: A. meteorite impact friction. B. decompression melting. C. fluid-induced melting. D. subduction friction melting.

fluid-induced melting

Very slow cooling is required in order to grow large crystals because it takes a long time: for ions to sink to the bottom of the magma body. for ions to float to the top of the magma. for the atoms to grow from protons, neutrons, and electrons. for the ions to move through magma and "find" the correct places on a growing crystal.

for the ions to move through magma and "find" the correct places on a growing crystal.

The Palisades sill is a good illustration of the process of: partial melting. fractional crystallization. explosive volcanism. basaltic volcanism.

fractional crystallization.

Which of the following volcanic features forms as a result of hydrothermal activity associated with hot volcanic rocks and magmas? A. diatremes B. fumaroles C. lahars D. fissure eruptions

fumaroles

Layers of sulfur form on active volcanoes around: A. craters. B. cones. C. fumaroles. D. flows.

fumaroles.

Which of the following igneous rocks is the most mafic? diorite gabbro granite andesite

gabbro

While basalt is erupting to the ocean floor at mid-ocean ridges, ___________ is crystallizing in underlying magma chambers. andesite granite diorite gabbro

gabbro

The major difference between lavas that produced a rhyolitic dome in Newberry Caldera, Oregon, versus the tremendous volume of volcanic ash at Yellowstone Park, Wyoming is: A. gases in the lavas at Newberry, not at Yellowstone. B. gases in the lavas at Yellowstone, not at Newberry. C. high SiO2 at Yellowstone, low at Newberry. D. high SiO2 at Newberry, low at Yellowstone.

gases in the lavas at Yellowstone, not at Newberry.

___ energy is the name for heat energy that is utilized in volcanically active areas such as Iceland. A. Geothermal B. Megawatt C. Geyser D. Hydroelectric

geothermal

Intraplate volcanism is most likely caused by: A. hot spots in the mantle. B. mid-ocean ridge heat. C. ancient meteorite impacts. D. uneven heating by the sun.

hot spots in the mantle

The processes of magmatic stoping explain which of the following occurrences? how different rocks can arise from the same parent magma the process whereby new oceanic crust is made at spreading centers from the melting of underlying mantle how rising magma makes space for itself in the Earth's crust the formation of ash clouds with volcanic eruptions

how rising magma makes space for itself in the Earth's crust

____________ leaches valuable minerals out of the new crust formed at mid-ocean ridges. A. Hydrothermal activity B. Volcanic eruptions C. Crystallization D. Melting

hydrothermal activity

The liquid magma that reaches Earth's surface is called: A. melt. B. intrusive. C. lava. D. glass.

lava

Basaltic lavas form shield volcanoes and flood basalts rather than steep stratovolcanoes because: A. high silica results in low-viscosity, fluid lava. B. low silica results in low-viscosity, fluid lava. C. low silica results in high-viscosity, pasty lava. D. high silica results in high-viscosity, fluid magma.

low silica results in low-viscosity, fluid lava.

What is the source of heat for the geysers, hot springs, and other thermal features of Yellowstone Park? A. hot water in the mantle under Yellowstone B. magma body under Yellowstone C. friction from huge meteorite impact D. huge underground fire in Wyoming coal beds

magma body under Yellowstone

Igneous rocks of Iceland: island arc andesites continental margin andesites mid-ocean ridge basalts continent-continent collision granites

mid-ocean ridge basalts

Which of the following gases is NOT an important constituent of volcanic gas? A. carbon dioxide B. nitrogen dioxide C. water vapor D. hydrochloric acid

nitrogen dioxide

The "Ring of Fire" contains volcanoes distributed around the: A. Atlantic Ocean. B. Indian Ocean. C. Pacific Ocean. D. South American continent.

pacific ocean

The coarsest-grained of all intrusive igneous rocks: granite. gabbro. diorite. pegmatite.

pegmatite

Which of the following pairs of intrusive and extrusive igneous rocks do not both have the same chemical composition? diorite and andesite granite and rhyolite peridotite and basalt All of the above pairs have the same chemical compositions.

peridotite and basalt

The dominant rock of Earth's mantle is: peridotite. granite. basalt. andesite.

peridotite.

What mineral is the most abundant in igneous rocks of intermediate composition? quartz pyroxene plagioclase feldspar olivine

plagioclase feldspar

A large igneous body formed at depth in Earth's crust: xenoliths. pyroclast. country rock. pluton.

pluton

The Mount Pelée eruption of 1902, a mixture of hot air and ash, was a: A. lava dome. B. flood basalt. C. pillow basalt. D. pyroclastic flow.

pyroclastic flow

The most plentiful minerals in peridotite are: pyroxene and quartz. biotite and plagioclase feldspar. orthoclase and quartz. pyroxene and olivine.

pyroxene and olivine.

What are the most common igneous rocks found in ophiolites? andesites and diorites basalts and gabbros rhyolites and granites pumice and obsidian

rhyolites and granites

The process of magmatic differentiation explains how: rocks of varying composition can arise from the same parent magma. magma chambers form in the Earth's crust. water lowers the melting temperature of rock. all igneous rocks end up with the same composition.

rocks of varying composition can arise from the same parent magma.

The Minoan civilization may have been essentially destroyed by the massive explosive eruption of: A. Santorini. B. Vesuvius. C. Etna. D. Tambora.

santorini

What is the proper term for the huge volcanoes with very gentle slopes? A. lava domes B. shield volcanoes C. composite volcanoes D. cinder cones

shield volcanoes

Lava viscosity increases as: A. silica content increases and lava temperature decreases. B. silica content decreases and lava temperature decreases. C. silica content increases and lava temperature increases. D. silica content decreases and dissolved gases increase.

silica content increases and lava temperature decreases.

Felsic, intermediate, and mafic igneous rock all are dominantly made up of ___________ minerals. carbonate sulfide oxide silicate

silicate

In what tectonic setting would you expect to find intermediate igneous rocks? mid-ocean ridges mantle plumes or "hot spots" subduction zones continental rifts

subduction zones

Most magmas form at what types of plate boundaries? mid-ocean ridges and transform faults subduction zones and transform faults mid-ocean ridges, transform faults, and subduction zones subduction zones and mid-ocean ridges

subduction zones and mid-ocean ridges

In 1816, known as "the year without a summer," summer frosts and snowstorms occurred in the Northern Hemisphere as a result of: A. meteorite impact. B. dust storms from drought blocking sun. C. lack of sun's energy. D. sunlight blocked by debris in atmosphere from eruption of Tambora.

sunlight blocked by debris in atmosphere from eruption of Tambora.

Bowen's Reaction Series summarizes: differences between intrusive and extrusive igneous rocks. the partial melting process. the fractional crystallization process. the different forms of intrusive igneous bodies.

the fractional crystallization process.

Why are lava domes associated with felsic lavas? A. They are made up of thin felsic fluid flows. B. The high SiO2 lavas bulge upward but won't flow. C. Their low SiO2 lavas are explosive. D. Lava domes are piles of pillow lavas.

the high SiO2 lavas bulge upward but won't flow

Immiscible magmas are: all basaltic. formed by partial melting. formed by fractional crystallization. two magmas that do not mix with one another.

two magmas that do not mix with one another

Kimberlite diatremes, known to host diamond deposits, are formed from magmas that have a ________ composition. A. ultramafic B. mafic C. felsic D. granitic

ultramafic

What types of rocks form from large, angular pyroclastic fragments?

volcanic breccias

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

volcanic domes

The presence of _________________ in subduction zones lowers the melting temperature and viscosity of resulting magmas over subduction zones.

water

The probable source of Earth's oceans and atmosphere is: A. the oceans and atmosphere formed when Earth formed. B. oceans were all water vapor in atmosphere when Earth formed. C. oceans and atmosphere are entirely from comet collisions with early Earth. D. water and atmosphere escaped from Earth's interior in volcanic eruptions.

water and atmosphere escaped from Earth's interior in volcanic eruptions.

Blocks of country rock that have fallen into magma and frozen in it as the magma crystallized: xenoliths. batholiths. sill. dike

xenoliths.