Geology exam 2

On this figure of Bowen's Reaction Series, which mineral would crystallize last from magma? 2, calcium-rich plagioclase 1, olivine 3, sodium-rich plagioclase 4, K-feldspar

K-feldspar

How are fissures formed? -Tectonics forces pull rocks apart leaving fractures that are filled by precipitates. -Magma pushes out the groundwater in the pore spaces of unconsolidated materials. -Pressure from magma pries open fractures in rock, and then magma fills the fracture.

Pressure from magma pries open fractures in rock, and then magma fills the fracture.

At what depth do rocks begin to ductilely deform in response to stress rather than brittlely deform? 3 km 15 km 8 km 26

15 km

Shale is metamorphosed into three rock types: (1) a banded gneissic rock; (2) a rock with small mica crystals with a shiny aspect; (3) a very shiny rock with large mica crystals; and (4) a dull slate with cleavage. Which of the following lists these rocks in order of increasing metamorphic grade?

4,2,3,1

How much silica do mafic rocks contain? 0-10% 44-55% 11-25% 26-44%

44-55

In what site on this figure would you expect high pressure/low temperature metamorphism?

A and B

Horizontal shear stresses, like those pictured, may produce... strike-slip faults in shallow parts of the crust. shear zones. metamorphism and ductile deformation at depth. All of these choices are correct.

All of these choices are correct.

Flood basalts influence life on Earth because eruptions can release large amounts of gas that warm the atmosphere. large volumes of flood basalts are erupted during a short time. eruptions can release large amounts of gas that cool the atmosphere. All of these choices are correct.

All of these choices are correct. (large volumes of flood basalts are erupted during a short time; eruptions can release large amounts of gas that cool the atmosphere; eruptions can release large amounts of gas that warm the atmosphere.)

Fold and thrust belts... All these describe fold and thrust belts. contain cleavage and joints. displace older rocks over younger ones. form where thrust faults cut through a thick sequence of layered rocks.

All these describe fold and thrust belts.

In what site on this figure would you expect low pressure/high temperature metamorphism?

C

What is the typical relationship of cleavage to folds? Cleavage is usually parallel to the axial surfaces of folds. Cleavage is usually earlier than the associated folds. Cleavage is usually later than the associated folds. Folds and cleavage do not typically occur together.

Cleavage is usually parallel to the axial surfaces of folds.

Based on the image and your knowledge of metamorphic minerals, which of the following is true? Garnet is diagnostic of moderate- to high-grade metamorphic conditions. Garnet tends to be formed under low-grade metamorphic conditions. Chlorite is diagnostic of the highest grade of metamorphic conditions. The occurrence of garnet cannot be used in conjunction with the occurrence of any other minerals for determining metamorphic conditions.

Garnet is diagnostic of moderate- to high-grade metamorphic conditions.

Which of the following is a good interpretation of the environmental significance of an attribute of a sedimentary rock? Red rocks typically form in deep oceans. None of these choices are correct. Thick bedding implies rapidly changing conditions. Fossils indicate that sediment was deposited in water. Graded beds indicate that the strength of the current decreased through time.

Graded beds indicate that the strength of the current decreased through time.

How does the addition of water cause melting? -It changes the location of the liquid-solid boundary. -It heats the rocks. -It decreases the pressure on the rocks. -It increases the temperature while decreasing the pressure.

It changes the location of the liquid-solid boundary.

What is the most likely change to this rock in response to metamorphism without deformation? It will develop foliation. The rock will not change. It will develop lineation. It will develop cleavage. New minerals will grow.

New minerals will grow.

What typically happens to the size, shape, and sorting of clasts as they are transported from steep mountains toward more gentle settings? The sediment becomes more poorly sorted. All these occur with transportation. The size of the clasts increases. The clasts become more rounded.

The clasts become more rounded.

How would the force and stress on the wooden pillar in this figure change if the stone weight was the same size but the wooden pillar were narrower? The amount of force and the amount of stress would both decrease. The force would remain the same, but the amount of stress would decrease. The force would remain the same, but the amount of stress would increase. The amount of force and the amount of stress would both increase. The amount of force and amount of stress would be unchanged.

The force would remain the same, but the amount of stress would increase.

What does this texture indicate about the formation of this rock? - The rock solidified at great depth. -The magma formed some crystals before rising closer to the surface and solidifying. -The magma had abundant dissolved gas. -It formed from an explosive pyroclastic eruption.

The magma had abundant dissolved gas.

What can you infer from this contact between an overlying conglomerate and underlying sandstone? There was a gradual switch from marine to nonmarine conditions. There was an abrupt event, such as a flood. The conglomerate was deposited by the wind. There was a gradual switch from nonmarine to marine conditions.

There was an abrupt event, such as a flood.

Which of the following is NOT true about flood basalts? They cover large areas and contain huge volumes of magma. They cover much of the Columbia Plateau of the Pacific Northwest. Some flood basalts erupted at about the same time as major extinctions of species. They are fed from large interconnected composite volcanoes.

They are fed from large interconnected composite volcanoes.

Which of the following is NOT a characteristic of a volcanic dome? The outer part of the dome contains blocks and other rubble. Many domes are associated with composite volcanoes and calderas. Some parts contain volcanic glass, such as obsidian. They are one of the largest types of volcanoes.

They are one of the largest types of volcanoes.

Which of the following are ways that viscosity affects gases in magma? Viscous magma prevents gas from escaping easily. Less viscous magma allows gas to escape, which can lead to very explosive eruptions. All these are ways that viscosity affects gases in magma. Abundant silica chains in viscous magma allow gas to pass quickly through the magma.

Viscous magma prevents gas from escaping easily.

A graded bed forms due to: a gradual change in the climate of the region. a gradual decrease in the strength of the current over time. a gradual change in global climate. the piling of sediment down the front of a dune or ripple. an abrupt change in the composition of the sediment.

a gradual decrease in the strength of the current over time

What setting was this sedimentary rock deposited in? a muddy place that sometimes dried out an arid place with sand that was moved by wind a quiet, deep water location a steep slope in the mountains

a muddy place that sometimes dried out

What type of volcanic eruption is shown in this photograph? a volcanic mudflow collapse of a volcanic dome a lava fountain a pyroclastic column a fissure eruption

a pryoclastic column

If you were designing a rock that resisted weathering, which of the following characteristics would it have? a quartz-rich rock a soluble chemical composition closely spaced fractures a rock composed of abundant loose pieces

a quartz rich rock

The most likely cause of graded bedding found in sedimentary rocks is... settling after uniform deposition. an increase in water current velocity. a reduction in water current velocity. a change in wind direction moving across the top of the water.

a reduction in water current velocity.

An ophiolite is a mixture of mafic and felsic magma within pillow basalts. a sliced-off piece of oceanic crust that has been thrust onto the edge of a continent or island. a mineral consisting of basalt and gabbro formed in the mantle.

a sliced-off piece of oceanic crust that has been thrust onto the edge of a continent or island.

Loose sand on the continental shelf or shelf slope that becomes unstable and flows downslope as a thick slurry of sediment and water is known as: a turbidity current. a marine sandstorm. an avulsion event. a sandslide.

a turbidity current.

Which of the following is the best indicator that a volcano might be very dangerous? rock analyses that indicate a low content of silica a volcano that contains andesite and welded tuffs gentle slopes that signify fast-flowing lavas ages that indicate the volcano last erupted 10 million years ago

a volcano that contains andesite and welded tuffs

All the following are tectonic settings where large magma chambers can form except above existing lava fields. mid-ocean ridges. continental collisions. hot spots. rifts.

above existing lava fields.

How does chert form? accumulation of silica-rich organisms or mixing of seawater and groundwater precipitation from seawater early in Earth's history evaporation of water in a lake or sea accumulation of microscopic organisms composed of calcium carbonate

accumulation of silica-rich organisms or mixing of seawater and groundwater

Under what conditions was this rock likely deformed? conditions that favored fracturing All of these choices are correct. relatively shallow brittle conditions

all are correct

Which of the following processes produce sedimentary clasts? All of these choices are correct. decomposition of granite into quartz grains and clay breaking of round cobbles as they are transported scouring and abrasion of bedrock along rivers fracturing of bedrock that results in angular pieces

all are correct

Bedding in sedimentary rocks is defined by: sediment size. all of the characteristics listed. resistance to erosion. thickness. color.

all of the charcteristics

A coarse-grained intrusive igneous rock composed mostly of feldspar and quartz is called... granite. basalt. andesite. gabbro. ryholite.

granite

Which of the following environments is NOT a setting in which limestone forms? coral reefs deposition of calcite near springs All these are environments in which limestone forms. some lakes accumulation of the remains of microscopic organisms

all of these are environments limestone forms

Which of the following are true of felsic magmas? High gas pressures commonly lead to highly explosive eruptions. All these are true of felsic magmas. They do not allow gas bubbles to escape easily. They tend to have high viscosities.

all of these are true of felsic magma

Which of the following activities is NOT used to monitor volcanoes? measuring seismic activity with seismic instruments measuring tilting on the flanks of a volcano All these are used to monitor volcanoes. measuring changes in heat flow from satellites measuring sulfur dioxide gas emissions

all of these are used to monitor volcanoes

Identify the factor(s) that strongly influence the size, shape, and/or sorting of sedimentary clasts... strength of current steepness of slope All of these choices are correct. agents of transport sediment supply

all of these choices

If you were designing a rock that would be easily weathered, which of the following characteristics would it have? a soluble chemical composition a rock composed of abundant pieces All of these choices are correct. a limestone in a wet climate closely spaced fractures

all of these choices

What chemical processes can occur during metamorphism and deformation? pressure solution remobilization All of these choices are correct. recrystalization

all of theses choices are correct

The main source of heat energy for Earth's interior is a direct result of -gamma decay, which is an unstable atom losing a photon. -beta decay, which is an unstable atom losing an electron. -alpha decay, which is an unstable atom losing 2 protons and 2 neutrons.

alpha decay, which is an unstable atom losing 2 protons and 2 neutrons.

The most common volcanic rock found in lava flows on composite volcanoes is... andesite. obsidian. basalt.

andesite

What type of structure is shown in this figure? downhill seat syncline monocline basin thrust fault anticline

anticline

A fine-grained mafic igneous rock is called... andesite. ryholite. granite. gabbro. basalt.

basalt

What type of volcanic eruption is probably shown in this photograph? basaltic lava flow caldera eruption fire fountain felsic lava flow pyroclastic flow

basaltic lava flow

If bubbles cannot escape easily from a magma, the resulting eruption is likely to... be explosive. be nonexplosive. produce long, thin lava flows.

be explosive

What type of metamorphic feature is shown in this photograph? hornfels normal fault cleavage thrust fault

cleavage

A relatively large, symmetrical volcano that contains interlayered lava flows, pyroclastic deposits, and volcanic mudflows is a.... shield volcano. volcanic dome. cinder cone. composite volcano. caldera.

composite volcano

What kind of metamorphism is occurring in this setting as indicated? regional contact hot water shearing

contact

What is the typical setting for fold and thrust belts? ocean-ocean divergent plate boundaries All of these choices are correct. continental rifts transform faults convergent plate boundaries

convergent plate boundries

The igneous feature shown in this figure is a -dike. -laccolith. -volcanic neck. -sill.

dike

A nonfoliated metamorphic rock not created by pressure or differential stress but by being baked by an igneous intrusion is a... schist. hornfels. phyllite. slate.

hornfels

Under what conditions was this rock likely deformed? conditions that favored fracturing relatively shallow hot and deep conditions brittle conditions

hot and deep conditions

An igneous rock that solidifies on Earth's surface is a(n) intrusive rock. extrusive rock. vesicular rock. magma rock.

extrusive rock

This igneous rock is -felsic and fine-grained. -felsic and coarse-grained. -mafic and fine-grained. -mafic and coarse-grained.

felsic and fine-grained.

What types of rocks would be most common in the volcano in this photograph? scoria and other vesicular basalt pillow basalts felsic and intermediate lava flows and tephra None of these choices are correct. basalt mostly formed in lava flows

felsic and intermediate lava flows and tephra

The deep-sea floor is characterized by sediment dominated by... calcite mud and other material derived from coral reefs. silt and sand derived from rivers and streams. fine dust and the remains of single-celled organisms.

fine dust and the remains of single-celled organisms.

Shield volcanoes commonly involve... volcanic domes. fluid lava flows. pyroclastic flows. All of these choices are correct. viscous lava flows.

fluid lava flow

What type of metamorphic feature is shown in this photograph? foliation in banded gneiss thrust fault hornfels cleavage in slate

foliation in banded gneiss

When basaltic lavas reach the ocean they... form pillow basalts. cause lava fountains at the vent on land. form circular calderas. All of these choices are correct. can flow long distances on top of the water.

form pillow basalts

Which of these attributes preserved in sedimentary rocks gives us the most information about past climates? imbrication fossils clast shape ripples bedding thickness

fossils

Which of the following is NOT a rock typically found within calderas? tuff gabbro welded rhyolite granite

gabbro

The geothermal gradient is the -increase of Earth's temperature with increase in depth. -decrease of Earth's temperature with increase of depth. -decrease of Earth's temperature on the surface as the Sun sets. -increase of Earth's temperature on the surface as the Sun rises.

increase of Earth's temperature with increase in depth.

A mantle plume rises because... it is propelled upward by gas coming out of the magma. it is solid but less dense than material around it. it is mostly molten. it is molten and more dense than material around it.

it is solid but less dense than material around it.

The igneous feature shown in this figure is a volcanic neck. -sill. -dike. -laccolith.

laccoliah

A sinkhole is most likely to form from dissolution in: conglomerate shale sandstone. chert. limestone.

limestone

Long, thin lava flows are typically produced by... low-viscosity lavas. high-viscosity lavas. collapsing eruption columns. volatile-rich eruptions.

low-viscosity lavas

An igneous rock rich in olivine and pyroxene is classified as __________ in composition. intermediate felsic mafic

mafic

According to the fossil record, what events have coincided with the approximate times when flood basalts were erupting? increased diversity of life climate stability and flourishing of life mass extinctions

mass extinctions

What type of structure is shown in this figure? syncline thrust fault monocline anticline basin

monocline

The largest concentration of composite volcanoes on Earth is located along the

pacific ring of fire

This photograph shows an iron formation. How does it form? accumulation of microscopic organisms composed of calcium carbonate precipitation from seawater early in Earth's history accumulation of silica-rich organisms or mixing of seawater and groundwater evaporation of water in a lake or sea

precipitation from seawater early in Earth's history

The transition from the gray shale and limestone to the sandstone and breccia above represents a: transgression regression

regression

The main cause of melting along subduction zones is the rise and decompression melting of mantle asthenosphere. -melting of the subducting plate. -release of water from the subducting plate. -rise and decompression melting of mantle lithosphere.

release of water from the subducting plate.

This image is demonstrating chemical __________ during metamorphism and deformation. shearing rotation remobilization pressure solution recrystallization

remobilization

What type of fault is shown in this figure? reverse fault strike-slip fault normal fault

reverse fault

What type of rock would you form in this environment, showing a dried up lake bed? coal limestone iron formation rock salt and other evaporite minerals chert

rock salt and other evaporite minerals

The main way water gets into a subduction zone is by -All of these choices are correct. -seawater introduced into oceanic crust at the mid-ocean ridge, prior to subduction. -rain associated with eruptions in the island arc. -a decrease in pressure that causes melting. heating of the overlying continental crust.

seawater introduced into oceanic crust at the mid-ocean ridge, prior to subduction.

A graywacke is a type of shale. sandstone. conglomerate. siltstone.

siltstone

The special geologic terms used to represent the direction of a horizontal line on an inclined surface (like in a fault) and the angle of that surface to the horizontal are... footwall and hanging wall. horst and graben. fracture and joint. strike and dip.

strike and dip

What is the plate-tectonic setting of Mount Rainier? subduction beneath the Pacific Northwest spreading along the Juan de Fuca ridge None of these choices are correct. a continent-continent collision a hot spot related to Yellowstone

subduction beneath the pacific northwest

If a rock is subjected to differential stress, then it means that... fluid pressure is greater than the confining pressure. stresses are pushing inward from all directions by the same amount. the amount of stress is greater in some directions than in others. forces are pushing inward from all directions by the same amount.

the amount of stress is greater in some directions than in others.

n this section, a lower gray rock is successively overlain by beach sandstone, lagoon mudstone, and limestone. What is the best interpretation of what was going on? The area was experiencing a transgression. Sea level was stable but the temperatures were getting warmer. None of these describe what was occurring. Sea level was stable but the temperatures were getting colder.

the area was experiencing a transgression

Imbricated clasts in this river means that: the wind was blowing from left to right. the current flowed from right to left. the rocks have slid downhill to the right. the rocks have been shuffled by ground shaking during an earthquake.

the current flowed from right to left

A lava solidifies into nonvesicular basalt instead of vesicular basalt because... the lava forms a ropy texture. the lava flow breaks apart as it flows. the lava has a low gas content. the lava flow forms lava tubes.

the lava has a low gas content.

Which of the rock layers in this figure was most likely deposited by sand dunes on land? the lower tan sandstone the lowest red sandstone the upper tan sandstone the reddish breccia None of these choices are correct.

the lowest red and sandstone

The higher the gas pressure builds in a magma.. the more explosive an eruption it is likely to produce. the longer the lava flows an eruption will produce. the less explosive an eruption is likely to produce. the more likely a volcanic done is to form.the more explosive an eruption it is likely to produce.

the more explosive an eruption is likely to produce

A finely crystalline or glassy igneous texture indicates that... the rock cooled quickly. the ash and pumice were hot and became compacted. the rock cooled slowly. the rock broke apart as it flowed. there was a lot of gas in the magma.

the rock cooled quickly.

A porphyritic igneous texture indicates that... the rock cooled slowly. the ash and pumice were hot and became compacted. the rock cooled slowly and then quickly. the rock broke apart as it flowed. there was water in the magma.

the rock cooled slowly and then quickly.

A vesicular igneous texture indicates that... the rock cooled slowly. the rock broke apart as it flowed. the rock cooled quickly. there was a lot of gas in the magma. the ash and pumice were hot and became compacted.

there was a lot of gas in the magma.

Which way was the current (either wind or water) moving during deposition of this section of rocks? toward the right away from the camera toward the left there is no way to tell toward the camera

toward the right

Downslope marine flows comprised of mixed masses of sand, mud, and water are called... longshore currents. turbidity currents. tidal currents.

turbidity currents

Which of the following units was most likely deposited in the deepest marine water? unit 3 unit 5 unit 4 unit 2 unit 1

unit 5

What type of basaltic feature is shown in this photograph? vesicles volcanic bomb aa lava flow pahoehoe lava flow pyroclastic flow

vesicles

Changes in topography, water chemistry, and gas output all are used to help predict... harmonic tremors. landslides. mudflows. volcanic eruptions.

volcanic eruptions

The relationship between weathering and erosion can best be characterized as... weathering loosens material after erosion has carried it away, but erosion can also scour and move unweathered material. weathering happens before erosion can occur. weathering happens once erosion has moved material. weathering loosens material before erosion carries it away, but erosion can also scour and move unweathered material.

weathering loosens material before erosion carries it away, but erosion can also scour and move unweathered material.

Which of the following attributes does NOT apply to these sediments? cobbles and boulders composed of gravel angular clasts well sorted

well sorted

Columnar joints, such as the ones shown in the photograph, are formed -when hot liquid igneous rock contracts. -when hot but solid igneous rock contracts. -when hot liquid igneous rock expands. -when hot but solid igneous rock expands.

when hot but solid igneous rock contracts.