geol midterm 2

Which letter in this classification table indicates the position of granite?

A

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

A and B

What is the difference between a joint and a fault?

A fault displaces the rocks on one side relative to another.

Which of the following changes in conditions could represent melting of continental crust from the introduction of a mafic magma?

A to B

Which of the following are NOT common in landscapes formed by carbonate rocks?

All of these are common in carbonate landscapes. sinkholes fractures widened by dissolution well-defined layers (beds) outcrops with pits or holes

What type of rock is shown in this photograph? fig 14

Breccia

What type of rock is shown in this photograph? fig 7

Breccia

Examine this figure and correctly complete this sentence using the proper phrase.

C to B Changing conditions from points C to B would result in decompression melting.

Which letter in this classification table indicates the position of gabbro?

D

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

If a rock is metamorphosed but does not contain foliation or lineation, what has probably happened to the rock?

It has been metamorphosed but not deformed.

Which of the following is characteristic of a transgression?

Marine sedimentary facies move toward the land.

Which of the following is NOT a reason why heat flow and gas output from a volcano tend to increase before eruptions?

Melting of snow caps dissolves large amounts of water into the magma.

Which of the following is the best example of heat transfer by conduction?

Newly created lithosphere loses heat to adjacent rocks

How does a cross bed form?

Piling of sediment down the front of a dune or ripple.

How does iron formation form?

Precipitation from seawater early in Earth's history.

What is typically occurring when magmatism occurs far away from plate boundaries?

Some type of thermal disturbance is occurring in the mantle.

Which of the following is NOT true about shield volcanoes in the landscape?

They are large mountains with steep slopes.

What is the best explanation for the shape of these clasts?

They have been transported a significant distance.

The cross beds shown here indicate what about the environment the sandstone was deposited in?

Water/wind flowed from right to left.

The deep-sea floor is characterized by sediment dominated by

fine dust and the remains of single-celled organisms.

Fractures that are simple cracks where the rock has pulled apart by a small amount are

joints.

Which of the following volcanoes is generally the largest?

shield volcano

Which of the rock layers in this figure was most likely deposited by sand dunes on land?

the lowest red sandstone

Correctly complete these sentences using the words provided.

- Steep and unstable slopes can produce landslides and mudflows, forming volcanic breccia. - Magma erupted on the surface can form a lava flow that cools quickly, resulting in volcanic glass. - Some volcanic ash rises vertically in an eruption column, cools before accumulating on the surface, and forms deposits that are nonwelded. - Some volcanic ash forms pyroclastic flows that accumulate while hot and can become welded to some extent.

Correctly complete these sentences using the words provided.

.

Drag the photographs so that they are in the correct order, arranged from the least metamorphosed (1) to most metamorphosed (4).

.

For the volcanic eruption in this photograph, complete the three missing parts of the sentence using the viscosity, composition, and resulting rock type.

.

These figures show three types of geologic structures. Drag the correct label below each figure.

.

These photographs show igneous rocks with different sizes of crystals. Drag the cooling rate to the photograph whose crystal size best reflects that cooling rate.

.

Which of the numbered features is a lava flow?

1

Which of the numbers on this figure indicates low pressure/high temperature metamorphic conditions?

1

Which location on this diagram would most likely record hot conditions deep within the continental crust?

4

Which of the numbered features is a pyroclastic flow?

4

On this figure of Bowen's Reaction Series, which mineral would crystallize last from magma?

4, K-feldspar

Which of the following is a hazard but not a risk, according to the textbook?

A scoria cone that erupts hot molten fragments on an unpopulated Pacific island

Which of the following sites near a volcano might be relatively less dangerous?

A site on a ridge as opposed to a site in a valley.

At which of the sites shown in this figure would melting probably be caused by introduction of water into hot rocks?

C

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

C

The effect of transportation on a pebble's particle size is best summarized by which statement?

Its size decreases.

Which of the following is characteristic of a regression?

Sand dunes and river sediments can be deposited over marine deposits.

In this section, a lower gray rock is successively overlain as follows: limestone is overlain by mudstone, which is overlain by beach sandstone. What is the best interpretation of what was going on? fig 11

The area was experiencing a regression

Imbricated clasts in this river mean.

The current flowed from right to left.

How would the force and stress on the wooden pillar in this figure change if the stone weight were the same size but the wooden pillar were narrower? fig 20

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

What happens to the majority of sediment being carried by moving water as it enters a standing body (little or no motion) of water?

The sediment gradually settles to the bottom.

For the sedimentary environment shown, complete the three missing parts of the sentence using the setting, type of clasts, and resulting rock type. fig 9

This figure shows a reef (setting) that would mostly have coral, shells, and remains of marine organisms (sedimentary material) and would produce limestone (sedimentary rock type).

For the volcanic eruption in this photograph, complete the three missing parts of the sentence using the viscosity, composition, and resulting rock type. fig 3

This figure shows an eruption of high-viscosity (viscosity) magma that probably has a felsic or intermediate (composition) and would form pumice (resulting rock type).

Which of the following are ways that viscosity affects gases in magma?

Viscous magma prevents gas from escaping easily.

The classic volcano shape is displayed by

a composite volcano.

Which of the following is least likely to be a volcano?

a hill capped by volcanic rocks

A formation is defined as

a rock unit that is distinct and laterally traceable.

Which of the following factors indicates a high risk for volcanic mudflows or lahars?

a volcano with a thick covering of snow or ice

All of the following are tectonic settings where large magma chambers can form EXCEPT

above existing lava fields.

Which of the following is NOT a way to form layers in a sedimentary rock?

all Occurrence of a discrete event like a flood. A change in the strength of the current. A change in the supply of sediment. A change in climate of the region.

Which of the following occurs in a lava tube?

all The surface of the lava flow solidifies to form a roof over the moving lava. Lava tubes insulate a lava flow, allowing it to flow farther. If a lava tube drains, it becomes a tube-shaped cave.

Which of the following is an example of heat transfer by convection?

all Water within a pan is heated and flows in a circular path. Seawater is drawn into a mid-ocean ridge, heated, and rises. The rise of material beneath mid-ocean ridges is coupled with subduction.

What causes the stress that forms joints?

all burial and tectonic forces cooling and contraction uplift and unloading of pressure

Hazards associated with basaltic lava flows and eruptions are

all burial of roads and neighborhoods by lava flows. house fires. floods from catastrophic melting of ice.

Which of the following was common to the eruptions of Vesuvius, Mount Pelée, and Mount St. Helens?

all composite volcanoes earthquakes before the eruption small eruptions of tephra pyroclastic flows

Which of the following characterizes a continental rift?

all contact metamorphism near magma chambers normal faults tension metamorphism associated with shearing

Which of the following is a common metamorphic process?

all deforming objects into new shapes rotation of minerals into a common orientation remobilization of chemical constituents into light and dark bands dissolving some parts of the rock and carrying the material away

What type of material likely composes this volcano?

all felsic to intermediate lava flows pyroclastic flows volcanic mudflows and landslides

What can occur in association with a thrust fault?

all folding of rocks as the fault grows or propagates upward folding of rocks as layers are forced up and over bends in the fault burial and metamorphism of rocks beneath the thrust fault

Which of the following processes produce sedimentary clasts?

all fracturing of bedrock that results in angular pieces breaking of round cobbles as they are transported scouring and abrasion of bedrock along rivers decomposition of granite into quartz grains and clay

Which of the following are characteristics of actively erupting volcanoes? fig 5

all glowing orange lava flowing downhill fragments of molten rock blasting into the air billowing clouds of ash rising into the air

Which of the following structures can be related to or can occur close to faults?

all joints tilted blocks anticlines synclines

Flood basalts influence life on Earth because

all 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.

Which of the following are dangerous aspects of composite volcanoes?

all pyroclastic flows landslides and mudflows an eruption column

Which of the following rocks cannot be metamorphosed?

all shale sandstone limestone granite

Identify the factor(s) that strongly influence the size, shape, and/or sorting of sedimentary clasts.

all steepness of slope sediment supply strength of current agents of transport

Some scientists think that Yellowstone could cause a future disaster because

all the area is part of a caldera. scientists think that magma is still present at depth. past eruptions from Yellowstone carried ash over a huge area of western North America. land near Yellowstone is uplifting in some places and subsiding in others.

Which of the following is characteristic of continental rifts?

all - Some magmas are felsic and intermediate. - Heat from hot, mafic magma can melt continental crust. - Solid asthenosphere undergoes decompression melting.

How could a rock at point C be melted?

all increase in temperature decrease in pressure increase in temperature accompanied by a decrease in pressure

Which of the following processes could result in a felsic magma?

all of these: - partial melting of an intermediate-composition source - partial melting of continental crust - formation and settling of mafic crystals in an intermediate magma

Which of the following occurs in a lava tube?

all- The surface of the lava flow solidifies to form a roof over the moving lava. Lava tubes insulate a lava flow, allowing it to flow farther. If a lava tube drains, it becomes a tube-shaped cave.

Which of the following is common in most calderas?

all- a large, circular depression with steep walls thick sequences of volcanic ash rounded mountains that are volcanic domes

Which of the following are characteristics typical of volcanic domes?

all- steep-sided rubble-covered surface often occur in clusters

Which are important ways that magma can rise through the crust?

all- through fractures that can form dikes pieces of the wall rocks can break off tectonic forces can help open pathways magma is hotter and less dense than surrounding rocks

A magma chamber is

an underground body of molten rock.

The most common volcanic rock found in lava flows on composite volcanoes is

andesite.

What type of fold is shown in this figure?

anticline

What type of structure is shown in this figure? fig 19

anticline

A fold in which rock layers warp up in the shape of an A is a(n)

anticline.

Melting glaciers tend to deposit most of the sediment they carry and create

at their terminus (end).

What type of metamorphic rock is shown here? fig 17

banded gneiss

The largest volcanic eruptions on Earth are floods of

basalt magma.

The igneous feature shown in this photograph is

batholith

If bubbles cannot escape easily from a magma, the resulting eruption is likely to

be explosive.

Why could the geologic setting in this figure cause metamorphism?

because it forces some rocks deeper as they are overridden by rocks above the fault

Most subduction-derived magma never reaches the surface. However, what is formed if this type of magma reaches the surface of a continent?

belts of volcanoes

Sediments with a large amount of sand are most likely at

braided river at C and delta at D.

Which of the following is most likely to occur at shallow crustal levels?

brittle deformation

What kind of volcano is in this figure? fig 4

caldera

What type of product is being produced from material in these quarries? fig 8

cement

The igneous rocks shown in this photograph are forming

columnar joints.

When a rock is buried deep in the Earth and experiences the same force from all sides, it is under

confining pressure.

Which of the following sites would have sand and silt deposited by slowing of the current?

delta at D

A sandstone with a pinkish or reddish color that is the result of oxidation of iron-bearing minerals indicates the sand was

deposited on land and exposed to air.

Which of the following is NOT a factor that affects the viscosity of magma?

depth

When a rock is subjected to tectonic forces and experiences stress that is not the same in all directions, it is under

differential stress.

The igneous feature shown in this figure is a

dike

An igneous rock that solidifies on Earth's surface is called a(n)

extrusive rock.

These figures show how rocks respond to different types of stress at shallow and deep levels of the crust. Drag each figure into its correct position in the table.

fig 16

For each figure, complete the two missing parts of the sentence using the type of volcano and type of eruption.

fig 2 Figure A shows a scoria cone (type of volcano) that forms from a lava fountain (type of eruption). Figure B shows a shield volcano (type of volcano) that forms from eruption of basaltic lava flows (type of eruption). Figure C shows a composite volcano (type of volcano) that forms from eruption of lava and ash (type of eruption). Figure D shows a volcanic dome (type of volcano) that forms from eruption of viscous, felsic lava (type of eruption).

The most common clastic sedimentary rocks are made of the clasts that are

fine grained (smaller than sand).

What type of metamorphic feature is shown in this photograph?

foliation in banded gneiss

What does the texture of this rock indicate about its cooling history? The magma cooled

for a while at some depth and then rose to the surface where it finished solidifying.

Which of the following changes in conditions would cause melting of a solid rock?

from A to B

Which of the following changes in conditions would represent heating during burial?

from A to C

How did the joints in this photograph form?

from cooling

A coarse-grained intrusive igneous rock composed mostly of feldspar and quartz is called

granite

What type of stress could form the fault in this figure?

horizontal tension

Continental rifts have a diverse suite of igneous rocks associated with them because melting occurs

in the mantle and in the crust.

An igneous rock that solidifies below the surface is called a(n)

intrusive rock.

Which of the following igneous rocks has a texture consistent with a magma that cooled and solidified slowly at first, followed by more rapid cooling?

large, early formed crystals surrounded by smaller, late formed crystals

What type of eruption is shown in this photograph?

lava flow

Which of the following features is younger than fault 1?

lava flow and granite

What type of metamorphic feature is shown in this photograph? fig 21

lineation

Hot spots in oceanic settings typically produce

lines or clusters of volcanic islands.

Lithifies can be defined as

loose sediment hardens into sedimentary rock

Which of the following minerals would likely crystallize early from magma?

mafic minerals

Volcanic eruptions can produce huge floods by

melting ice sheets.

What type of rock forms through solid-state alteration of a previously existing rock, by heating, pressure, and/or fluid chemistry?

metamorphic

Which of the following is NOT involved in turning some sediment into sedimentary rock?

metamorphism

What type of structure is shown in this figure? fig 18

monocline

What tectonic setting is interpreted to be the cause of volcanism at Yellowstone?

movement of North America over a mantle plume

Which environment is least likely to deposit sand?

open ocean away from land

What type of basaltic feature is shown in this photograph?

pahoehoe lava flow

Drag the label of each rock texture over the photograph that corresponds to this texture

pegmatite coarse grained medium grained fine grained glassy porphyritic

The two main processes by which sediment is produced are

physical and chemical weathering.

Which of the following rock types requires dissolved gas in the magma?

pumice

Rocks rich in what mineral tend to have a poor solubility during weathering?

quartz

What type of metamorphism would occur in this setting?

regional metamorphism

Sedimentary facies shift toward the sea as the sea moves out during a

regression.

What is a main hazard of this type of volcano? (dome)

relatively small pyroclastic eruptions caused by localized explosions or collapse

What type of rock would you form in this environment, showing a dried up lake bed? fig 12

rock salt and other evaporite minerals

Which of the following materials is NOT produced by erupting volcanoes?

sandstone

This volcano is relatively small and composed of volcanic cinders. What kind of volcano is it?

scoria cone fig 1

Clastic sedimentary rocks are classified primarily on the basis of

sediment size.

What type of stress formed the structure shown in this figure?

shear

This volcano is broad and low, and is composed of basaltic lava flows. What kind of volcano is it?

shield volcano

The igneous feature shown in this figure is a

sill

The special geologic terms used to represent the direction of a horizontal line on an inclined surface (as in a fault) and the angle of that surface to the horizontal are

strike and dip.

Shield volcanoes have low slopes primarily because fig 6

the low viscosity of basaltic magma allows it to flow downhill for long distances.

Fluvial refers to

the processes and sediment of streams and rivers.

A porphyritic igneous texture indicates that

the rock cooled slowly and then quickly.

Coarsely crystalline igneous textures indicate that

the rock cooled slowly.

Sorting describes

the size range of clasts in sediment.

What does the horizontal line along the intersection of the plane and the water represent?

the strike of the surface

Which of the following environments would most likely have sediment formed by evaporation of seawater? fig 10

tidal flat at E

Which of the following is NOT a characteristic of an actively erupting volcano?

totally covered in a fresh blanket of clean, white snow

Which way was the current (either wind or water) moving during deposition of this section of rocks? fig 13

toward the right

Which of the following units was most likely deposited along an ancient mountain front? fig 15

unit 1