Deck 21: Glaciers: the Work of Ice

Question 1

How much of the land surface is covered by ice?

A)approximately 10%
B)approximately 50%
C)approximately 30%
D)approximately 80%

Answer 1

A

Question 2

In a valley glacier,where is the ice velocity the fastest?

A)along the base of the glacier
B)along the sides of the glacier
C)along the top center of the glacier
D)The ice velocity is constant throughout the glacier.

Answer 2

C

Question 3

Which of the following will cause sea level to rise?

A)the melting of a very large iceberg
B)the melting of the Ross ice shelf
C)the melting of the Greenland ice cap
D)all of the above

Answer 3

C

Question 4

In a bitterly cold climate,glaciers will move primarily by

A)basal slip.
B)calving.
C)plastic flow.
D)sublimation.

Question 5

Which of the following describes the transformation of ice to gaseous water vapor?

A)boiling
B)calving
C)melting
D)sublimation

Question 6

Why do glacial crevasses form?

A)because glacial meltwater erodes small valleys as glacial rivers flow
B)because plate tectonic forces deform the glacier
C)because the glacial surface is brittle and cracks as the ice flows
D)because the glacial surface partially melts,leaving holes and cracks

Question 7

A snow deposit contains approximately 90% air.How much air does glacial ice contain?

A)approximately 5%
B)approximately 20%
C)approximately 50%
D)approximately 90%

Question 8

Which of the following lists is written in order of increasing ice "metamorphism"?

A)snow,granular ice,firn,glacial ice
B)snow,firn,glacial ice,granular ice
C)snow,firn,granular ice,glacial ice
D)snow,granular ice , glacial ice,firn

Question 9

If a very large iceberg in the ocean were to melt,what would happen to sea level?

A)The sea level would decrease slightly.
B)The sea level would remain the same.
C)The sea level would increase slightly.
D)The sea level would decrease or increase depending on the air content of the iceberg.

Question 10

Which of the following statements is correct?

A)Continental and valley glaciers both move mostly by basal slip.
B)Continental and valley glaciers both move mostly by plastic flow.
C)Continental glaciers move mostly by basal slip; valley glaciers move mostly by plastic flow.
D)Continental glaciers move mostly by plastic flow; valley glaciers move mostly by basal slip.

Question 11

If accumulation exceeds ablation,then

A)the glacial ice will flow downhill and the glacial front will move downhill.
B)the glacial ice will flow downhill,but the glacial front will move uphill.
C)the glacial ice will flow uphill,but the glacial front will move downhill.
D)the glacial ice will flow uphill and the glacial front will move uphill.

Question 12

If the hypothesis that proposes that Earth was entirely covered with ice during late Precambrian time - Snowball Earth - is correct,then what process brought it out of that state?

A)the Sun heated up
B)atmospheric pressures fell allowing the ice to sublime
C)heat conduction through the oceanic lithosphere melted the ice
D)volcanic eruptions heated the atmosphere by emitting greenhouse gases

Question 13

Which of the following is an extremely slow-moving sheet of ice that covers vast land areas?

A)an arête
B)a continental glacier
C)an ice shelf
D)a valley glacier

Question 14

Where is the largest mass of ice on Earth located?

A)Antarctica
B)Greenland
C)the Himalayas
D)Siberia

Question 15

Which of the following forms of ice has the greatest density?

A)firn
B)glacial ice
C)granular ice
D)snow

Question 16

How fast can surging glaciers move?

A)approximately 5 meters per year
B)approximately 5 kilometers per year
C)approximately 100 meters per year
D)approximately 100 kilometers per year

Question 17

The snow line is

A)the lowest altitude at which snow will fall in summer.
B)the lowest altitude at which snow will fall in winter.
C)the altitude above which snow does not completely melt in summer.
D)the altitude above which snow does not completely melt in winter.

Question 18

Why are Earth's poles colder than the equator?

A)because Earth's poles are farther from the Sun than Earth's equator
B)because the sun strikes Earth at a lower angle at the poles than at the equator
C)because there are fewer hours of sunlight at the poles than at the equator
D)because there is more snow at the poles than at the equator

Question 19

At the equator,at what altitude is the snow line?

A)lower than 1000 meters
B)approximately 2500 meters
C)approximately 5000 meters
D)approximately 10,000 meters

Question 20

How thick are the Greenland and Antarctic ice caps?

A)approximately 100 meters thick
B)approximately 300 meters thick
C)approximately 1 kilometer thick
D)approximately 3 kilometers thick

Question 21

How thick is permafrost?

A)up to 5 meters thick
B)up to 50 meters thick
C)up to 500 meters thick
D)up to 5000 meters thick

Question 22

Which of the following glacial deposits is the most poorly sorted?

A)an esker
B)a kame
C)a moraine
D)a varve

Question 23

Glacial drift that has been modified,sorted,and distributed by meltwater streams is called

A)moraine.
B)outwash.
C)rock flour.
D)till.

Question 24

Which of the following features can be used to determine the direction a continental glacier moved?

A)drumlins
B)roches moutonées
C)striations
D)all of the above

Question 25

How much of Earth's land surface is permanently frozen?

A)approximately 1%
B)approximately 5%
C)approximately 10%
D)approximately 25%

Question 26

Which of the following erosional features is characteristic of rivers and not glaciers?

A)an arête
B)a cirque
C)a roche moutonée
D)a V-shaped valley

Question 27

What are fjords?

A)amphitheater-like hollows carved from mountains by glaciers
B)glacial valleys flooded with seawater
C)long,winding ridges of sediment found in the middle of ground moraines
D)steep-sided lakes located on glacial outwash plains

Question 28

Which of the following is deposited directly from ice?

A)an esker
B)a kame
C)a moraine
D)a varve

Question 29

What is the general term for all sediment of glacial origin?

A)drift
B)moraine
C)outwash
D)till

Question 30

Which of the following would be the most suitable site for a commercial sand and gravel pit?

A)an arête
B)a drumlin
C)a kame
D)a varve

Question 31

Which of the following agents of erosion deposits the most poorly sorted sediment?

A)ice
B)ocean currents
C)streams
D)wind

Question 32

Which of the following terms describes a glacial erosional feature as opposed to a glacial deposit?

A)erratic
B)fjord
C)outwash
D)till

Question 33

Which of the following terms describes an accumulation of rocky,sandy,or clayey material deposited at the end of a glacier?

A)dune
B)esker
C)loess
D)moraine

Question 34

The age of the last glacial period is estimated by carbon-14 dating of

A)logs in the glacial drift.
B)marine organisms contained in glacial ice.
C)plant leaves contained in the glacial drift.
D)wooly mammoths in glacial ice.

Question 35

Which of the following statements about varves is true?

A)Clay layers are deposited in summer and silt layers are deposited in winter.
B)Silt layers are deposited in summer and clay layers are deposited in winter.
C)Sand layers are deposited in summer and gravel layers are deposited in winter.
D)Gravel layers are deposited in summer and sand layers are deposited in winter.

Question 36

What are glacial striations?

A)dust formed by grinding rocks to clay-sized particles during glacial movement
B)grooves created by rocks scratching against bedrock at the base of a glacier
C)large,streamlined hills of till and bedrock that parallel the direction of ice movement
D)long,narrow,winding ridges of sand and gravel found in the middle of ground moraines

Question 37

How do kettles form?

A)by the melting of large blocks of ice left by a glacier
B)by melting permafrost
C)by meltwater streams running through glacial tunnels
D)by seasonal deposition of coarse and fine sediment

Question 38

During the last ice age the continents were ______ than today.

A)smaller
B)larger
C)the same size
D)in some cases larger and the other cases smaller

Question 39

When two cirques at the heads of adjacent valleys meet at the moutaintop,they produce a sharp,jagged crest called

A)an arête.
B)a drumlin.
C)a fjord.
D)a moraine.

Question 40

Which of the following is a depositional feature rather than an erosional feature?

A)an arête
B)a cirque
C)an esker
D)a hanging valley

Question 41

Glaciers ablate by

A)sublimation.
B)calving.
C)melting.
D)sublimation,calving,and melting.

Question 42

When a glacier remains the same size for a long time it means that

A)there is no movement in the glacier.
B)there is no accumulation.
C)ablation is absent.
D)accumlation and ablation are equal.

Question 43

During the peak of the last ice age,sea level was ______ than sea level today.

A)approximately 1 meter lower
B)approximately 10 meters lower
C)approximately 100 meters lower
D)approximately 1000 meters lower

Question 44

Glaciers tend to move by _________ in cold regions and ________ in temperate regions.

A)basal slip; plastic flow
B)plastic flow; ductile flow
C)ductile flow; surge flow
D)plastic flow; basal slip

Question 45

Which of the following is not one of the possible explanations for previous ice ages?

A)changes in the large-scale oceanic circulation
B)increases in the amount of carbon dioxide in the atmosphere
C)large land masses (continents)positioned at the poles
D)periodic changes in Earth's eccentricity

Question 46

Icebergs form through a process called

A)ablation.
B)accumulation.
C)sublimation.
D)calving.

Question 47

At what time in Earth's history do some geologists speculate that Earth was completely covered in ice?

A)1)8 to 0.01 million years ago (Pleistocene)
B)300 to 250 million years ago (Pennsylvanian-Permian)
C)750 to 600 million years ago (late Proterozoic)
D)4)5 to 4.0 billion years ago (Hadean)

Question 48

Lithified glacial till deposits in the rock record are called

A)varves.
B)tillites.
C)conglomerates.
D)moraines.

Question 49

Generally,it will take _________ for firn to turn into glacial ice.

A)a few hours
B)a few days
C)a few years
D)tens of years

Question 50

Glacial deposits preserved in the rock record provide evidence for major continental glaciations during

A)the Ordovician period
B)Precambrian time.
C)the Permian-Pennsylvanian periods.
D)the Ordovician period,Precambrian time,and the Permian-Pennsylvanian periods.

Question 51

During glacial maximas,

A)ice volumes are high and temperatures are high.
B)ice volumes are high and temperatures are low.
C)ice volumes are low and temperatures are low.
D)ice volumes are low and temperatures are high.

Question 52

Which of the following has an ice shelf?

A)Antarctica
B)Arctic
C)Greenland
D)Alaska

Question 53

What triggered the Pleistocene ice ages?

A)an increase in greenhouse gases
B)Milankovitch cycles
C)a shift in Earth's axis of rotation
D)Geoscientists are still uncertain.

Question 54

The main force that drives glacial flow is

A)gravity.
B)tides.
C)wind.
D)the Moon.

Question 55

The fine-silt to clay-sized material produced from the grinding action of glaciers is called

A)rock salt.
B)rock flour.
C)striations.
D)glacial debris.

Question 56

Which of the following would not be considered a glacier?

A)Antarctica
B)Arctic
C)Greenland
D)All of the above.

Question 57

Which of the following sequences shows a continuous decrease in air content?

A)glacial ice,granular ice,firn
B)granular ice,firn,glacial ice
C)firn,glacial ice,granular ice
D)firn,granular ice,glacial ice

Question 58

When did the last ice age end?

A)about 100 years ago
B)about 10,000 years ago
C)about 1 million years ago
D)about 100 million years ago

Question 59

When did the most recent ice ages occur?

A)the Jurassic period
B)the Pleistocene epoch
C)the Paleozoic era
D)the Pliocene epoch

Question 60

The __________ hypothesis proposes that Earth was entirely covered with ice during the late Precambrian.

A)Snowball Earth
B)Ice Ball
C)Tillite
D)Frozen Earth

Question 61

If a large glacier is fed by three separate valley glaciers then how many medial moraines,at the most,would you expect to see on top of it?

A)one
B)two
C)three
D)four

Question 62

Which of the following ice formations has the most extensive ice shelf?

A)Antarctica
B)Arctic
C)Greenland
D)Alaska

Question 63

When a glacier moves like a stack of cards that has been shifted,the movement is called

A)ice flow.
B)plastic flow.
C)a surge.
D)basal slip.

Question 64

_______ are glacial landforms that are called "sheep backs" in some countries and "whale backs" in other countries,such as Iceland.

A)Eskers
B)Roche moutonées
C)Drumlins
D)Kames

Question 65

A given layer of glacial ice initially formed from a layer of snow that fell

A)the same year.
B)the year before.
C)10 to 20 years before.
D)hundreds of years before.

Question 66

In glaciers where the speed of ice flow decreases with depth,we have

A)a surge.
B)basal slip.
C)plastic flow.
D)block flow.

Question 67

In order to be called a glacier a mass of ice must

A)reach a certain thickness.
B)have lost most of its trapped air.
C)reach a certain areal extent.
D)move downhill.

Question 68

Striations are particularly useful for measuring the direction of ice flow for

A)valley glaciers.
B)continental glaciers.
C)ice shelves.
D)cirque glaciers.

Question 69

Movement of past glaciers can be determined by looking at

A)rock flour.
B)striations.
C)outwash deposits.
D)glacial erratics.

Question 70

How many lateral moraines are needed to make one medial moraine?

A)one
B)two
C)three
D)four

Question 71

A large glacier has three medial moraines on top of it.How many valley glaciers must have a fed it?

A)one
B)two
C)three
D)four

Question 72

In glaciers undergoing basal slip,the flow rates will _____________ with depth.

A)increase
B)vary erratically
C)decrease
D)remain constant

Question 73

Which of the following glacial deposits is the best sorted?

A)an esker
B)a kame
C)a moraine
D)a varve

Question 74

In a valley glacier located in a cold region the flow rate will

A)increase with depth.
B)increase from center to the sides.
C)be constant throughout the glacier.
D)decrease with depth.

Question 75

Which of the following agents of erosion has the greatest competence?

A)ice
B)ocean currents
C)streams
D)wind

Question 76

When a glacier moves as a block of ice,the movement is called

A)ice flow.
B)plastic flow.
C)a surge.
D)basal slip.

Question 77

The oldest confirmed glaciations occurred approximately _________ years ago.

A)10,000
B)750 Ma
C)2.4 Ga
D)4.4 Ga

Question 78

Geologist Louis Agassiz measured the movement of glaciers with

A)GPS.
B)radar.
C)lasers.
D)stakes.

Question 79

The process by which icebergs are formed is called

A)breaking.
B)splitting.
C)cracking.
D)calving.

Question 80

The oldest confirmed glaciations occurred during the

A)Ordovician period.
B)Proterozoic eon.
C)Permian-Pennsylvanian periods.
D)Pleistocene epoch.