Deck 18: Glaciers: Cold-Climate Sculptors of Continents

Question 1

"All glacial ice must melt slightly before it can become denser." Evaluate this statement.

A) This statement is true; especially in Alaska where summers are warm.
B) This statement is true. Glacial ice formed by melting and pressure becomes denser than water.
C) This statement is false. Snow can go through metamorphosis to ice over time without melting.
D) This statement is false. Glacial snow and ice may melt and reform, but they do not get denser.

Answer 1

C

Question 2

What is the Mohs hardness of ice?

A) 0.15
B) 0.5
C) 1.5
D) 15.0

Answer 2

C

Question 3

Which type of glacier does the most erosional work?

A) relatively large glaciers
B) relatively fast glaciers
C) valley glaciers
D) relatively warm glaciers

Answer 3

D

Question 4

What agent polishes rocks smooth as a glacier passes?

A) meltwater
B) glacial flour
C) ice
D) transported pebbles

Question 5

A small, unconfined glacier is known as

A) a moraine.
B) an ice cap.
C) an ice sheet.
D) a valley glacier.

Question 6

Which event does not occur as snow metamorphoses into ice?

A) Grains pack more densely.
B) Grains become more pointed.
C) The ice becomes nonporous.
D) Ice molecules move past each other.

Question 7

Glaciers cover ________ of Earth's surface and contain ________ of Earth's fresh water.

A) 1%, 90%
B) 5%, 41%
C) 14%, 63%
D) 10%, 84%

Question 8

Accumulated rock-fall debris along the margin of a glacier is called

A) a lateral moraine.
B) a medial moraine.
C) an esker.
D) a kame.

Question 9

Which landform is described as a steep-sided amphitheater depression or half bowl high on a mountain side at the head of a glacially eroded valley?

A) an arete
B) a horn
C) a cirque
D) a tarn

Question 10

"Glaciers have no defined cleavage planes, but instead flow plastically." Evaluate this statement.

A) This statement is true, but it only applies to the upper part of a glacier.
B) This statement is false. Ice has cleavage similar to the mineral mica, and ice behaves like mica would under the same pressure.
C) This statement is partially true. The flow of glaciers is very slow and more similar to gravel than to plastic.
D) This statement is false. Glaciers do flow plastically, but also have well-defined cleavage planes similar to mica.

Question 11

Where are glaciers fastest?

A) in the Alps
B) in Greenland
C) in Antarctica
D) There is no clear difference between continents.

Question 12

How much greater is the shear stress of the Athabasca Glacier than the Mississippi River?

A) 2 times
B) 4 times
C) 10 times
D) 100 times

Question 13

Which is not a way that warm basal temperatures help glaciers slide?

A) Water recrystallizes in a denser form, resulting in more sliding.
B) Water lubricates the surface between the ice and the underlying rock by reducing friction.
C) Water reduces cohesion with underlying rock or regolith.
D) Water is pressurized by the weight of the ice and lifts the glacier off the regolith below.

Question 14

Glacier movement is not due to

A) gravity.
B) plastic flow.
C) friction.
D) basal slip.

Question 15

Which type of glacier most resembles a river?

A) an ice sheet
B) an ice cap
C) a small glacier
D) a valley glacier

Question 16

How do glaciers move?

A) uniformly, as one rigid chunk
B) faster at the edges and slower in the middle
C) faster in the middle and slower at the edges
D) faster on top, slower in the middle, and faster on the bottom

Question 17

Which depositional landform is named after a Gaelic word meaning "rounded hill"?

A) moraine
B) kame
C) esker
D) drumlin

Question 18

Ice in a retreating glacier

A) remains stationary.
B) moves downslope.
C) moves upslope.
D) may move downslope or upslope.

Question 19

Which depositional landform is described as a long, steep-sided curving ridge of alluvium that filled an ice tunnel beneath a glacier and was left behind when the glacier melted?

A) moraine
B) kame
C) esker
D) drumlin

Question 20

The lower snowline of the past meant that

A) glaciers existed at lower altitudes.
B) there were fewer glaciers.
C) there were glaciers at lower latitudes.
D) on average, there was less snow than there is today.

Question 21

What fraction of Earth's fresh water is held in the Great Lakes?

A) 1/20
B) 1/10
C) 1/5
D) 1/2

Question 22

Kettle lakes form by

A) melting blocks of ice.
B) abrasion of ice.
C) meltwater action under ice.
D) plucking of huge rocks.

Question 23

Which type of rock flanks Lake Superior?

A) shale
B) evaporite sedimentary rock
C) volcanic and sedimentary rock
D) metamorphic rock

Question 24

Which of the following glacial features is depositional?

A) moraine ridges
B) hanging valley
C) knife-edged ridge
D) pointed peak

Question 25

What percent of Antarctica's wastage is due to iceberg formation?

A) 80%
B) 60%
C) 40%
D) 20%

Question 26

Which of the following is not a difference between sea ice and ice shelves?

A) composition
B) where they form
C) where they exist
D) how long they exist

Question 27

The most likely form of erosion that causes cirques to form is

A) abrasion.
B) plucking by ice.
C) scouring by ice.
D) meltwater action.

Question 28

What does the profile of a glacial valley look like?

A) V-shaped
B) U-shaped
C) irregularly eroded
D) broad bottomed with overhangs

Question 29

For a glacier to float in water, the water must be

A) at least 10 m deep.
B) almost as deep as the iceberg is thick.
C) half as deep as the iceberg is thick.
D) two times as deep as the iceberg is thick.

Question 30

From which type of rock were Lake Michigan and Lake Huron carved?

A) shale
B) evaporite sedimentary rock
C) volcanic and sedimentary rock
D) metamorphic rock

Question 31

Which is not a common characteristic of an outwash stream?

A) a braided channel pattern
B) extremely fast flow
C) a milky color
D) a heavy sediment load

Question 32

Sediment carried away from a glacier by meltwater streams is called

A) till.
B) outwash.
C) unsorted sediment.
D) erratics.

Question 33

Which factor contributes most to icebergs breaking away from glaciers?

A) wave action
B) melting
C) sedimentation
D) freezing

Question 34

Tidewater glaciers

A) are pushed out by the action of the tides.
B) are pushed out by the action of rivers.
C) rest on the bottom of the sea until they reach deeper water.
D) melt almost as soon as they reach the sea.

Question 35

What is Canada's average depth of erosion?

A) 2 m
B) 20 m
C) 200 m
D) 200 km

Question 36

Evaluate this statement. "Glacial meltwater is milky white due to air bubbles trapped in the water."

A) This statement is true.
B) This statement is false. The color is due to glacial flour in the water.
C) This statement is false. The color is due to ice crystals.
D) This statement is partially true, because the milky-white color is also due to ice crystals.

Question 37

Most of Minnesota's lakes are

A) formed by outwash streams.
B) formed by blockage of a valley with an end moraine.
C) formed by glacial overdeepening.
D) kettle lakes.

Question 38

Which is not a characteristic of glacial deposits?

A) uniformity
B) faceted faces and edges
C) striations
D) poorly sorted

Question 39

The U-shape of a glacial valley is explained by

A) variation in glacier velocity.
B) the weight of overlying snow.
C) the action of meltwater.
D) the action of transported pebbles and boulders.

Question 40

Evaluate the statement. "Lateral moraines may form at any glacier."

A) This statement is true.
B) This statement is true, but only under certain favorable conditions.
C) This statement is false. Lateral moraines form only at ice caps.
D) This statement is false. Lateral moraines form only at valley glaciers.

Question 41

Which climatic factor is described as the angle between the vertical and rotational axis?

A) the obliquity
B) the eccentricity
C) the precession
D) the Milankovitch cycle

Question 42

A narrow, knife-edge ridge separating glacially eroded valleys or cirques is called a(n)

A) esker.
B) arete.
C) drumlin.
D) horn.

Question 43

Why does the ratio of oxygen 18 to oxygen 16 in the oceans increase during an ice age?

A) More precipitated water remains on land instead of running back to the sea.
B) There is a different kind of radioactivity occurring in the ocean at the colder world temperatures.
C) There is a different kind of radioactivity occurring on land at the colder world temperatures.
D) Sea water freezes into glaciers.

Question 44

A very steep pointy mountain peak sculpted between three or more cirques is called a(n)

A) horn.
B) arete.
C) roche moutonee.
D) esker.

Question 45

Why didn't ice gather in central and northern Alaska in the last ice age?

A) Proximity to the sea kept it too warm.
B) The climate at that time was tropical.
C) There was too little precipitation.
D) There was too much geothermal heating from volcanic action.

Question 46

A glacially formed lake within a cirque is called a

A) roche moutonee.
B) cirque.
C) tarn.
D) horn.

Question 47

What fraction of North America was covered by ice at the peak of the last ice age?

A) 1/4
B) 1/3
C) 2/3
D) 5/6

Question 48

The isotopic record have peaks and troughs with a wavelength of all of the following except

A) 12,000 years.
B) 23,000 years.
C) 41,000 years.
D) 100,000 years.

Question 49

Small (< 50,000 square kilometers) broad unconfined glaciers are called

A) ice caps.
B) ice sheets.
C) crevasse glaciers.
D) valley glaciers.

Question 50

Oxygen-isotope data has a pattern that led scientists to examine which other type of data in a search for the cause of ice ages?

A) rock-isotope data
B) planetary-movement data
C) continental-movement data
D) sun-activity data

Question 51

An elongate bedrock ridge eroded by a glacier parallel to the direction of glacier movement is called a(n)

A) horn.
B) arete.
C) cirque.
D) roche moutonee.

Question 52

Which cause and effect statement concerning the last ice age is incorrect?

A) Cooler climate affected vegetation distribution.
B) The Bering land bridge, which allowed human migration, existed due to changed coastlines.
C) Continent outlines were different because of lower sea levels.
D) Large lakes existed in the Northeast United States because of diminished evaporation.

Question 53

Evaluate the following statement. "Human activities contributing to global warming could cause the oceans to switch to ice-age mode."

A) This statement is true.
B) This statement is false. Changes in human behavior will alleviate any global warming trends.
C) This statement is false. Ice ages only begin when Earth is a certain distance from the Sun.
D) This statement is partially true. Global warming may cause a change in the oceans, but it is a natural process that is unrelated to human activity.

Question 54

When is the earliest time that scientists believe that people may have migrated to the west coast of North America from Asia?

A) 100,000 years ago
B) 41,000 years ago
C) 22,000 years ago
D) 12,000 years ago

Question 55

Which two factors act together to cause changes in the Earth-Sun distance at the seasonal solstices and equinoxes?

A) the obliquity and the eccentricity
B) the precession and the Milankovitch cycle
C) the eccentricity and the precession
D) the Milankovitch cycle and the obliquity

Question 56

Judge the following sentence according to the criteria given below. It is usually very easy to piece together a complete history of a regions older glaciations because the latest glacial advance typically preserves the older deposits.

A) The assertion and the reason are both correct, and the reason is valid.
B) The assertion and the reason are both correct, but the reason is invalid.
C) The assertion is correct but the reason is incorrect.
D) The assertion is incorrect but the reason is correct.
E) Both the assertion and the reason are incorrect.

Question 57

What was the effect of glaciation on soil fertility?

A) It increased fertility all over Canada.
B) It decreased fertility all over Canada.
C) It increased fertility in northern Canada, but decreased it in the Ohio River basin.
D) It decreased fertility in northern Canada, but increased it in the Ohio River basin.

Question 58

The elevation above which snow persists throughout the year is called the

A) snowline.
B) glacier.
C) zone of wastage.
D) zone of accumulation.

Question 59

Judge the following sentence according to the criteria given below. Oxygen 18 and Oxygen 16 are called stable isotopes because they are the stable products of radioactive decay.

A) The assertion and the reason are both correct, and the reason is valid.
B) The assertion and the reason are both correct, but the reason is invalid.
C) The assertion is correct but the reason is incorrect.
D) The assertion is incorrect but the reason is correct.
E) Both the assertion and the reason are incorrect.

Question 60

A steep-sided amphitheater at the head of a glacially eroded valley is called a

A) roche moutonee.
B) horn.
C) tarn.
D) cirque.

Question 61

How do glacial lakes form?

Question 62

Ice moves ________ in the zone of accumulation and ________ in the zone of wastage.

A) downward, upward
B) downward, downward
C) upward, downward
D) upward, upward

Question 63

How was Great Salt Lake formed?

Question 64

Glacial striations form by

A) melting.
B) plucking.
C) abrasion.
D) flow.

Question 65

A crevasse stops in a glacier at a depth

A) equal to the crustal boundary.
B) where plastic deformation occurs.
C) of 50 meters.
D) located at the rock or regolith below the glacier.

Question 66

The formation of glacial ice forms at

A) the same depth everywhere because the pressure of metamorphism cannot vary.
B) different depths depending on the how it forms.
C) different depths because the pressure of metamorphism can vary.
D) the same depths as long as the snowfall is constant in different regions.

Question 67

The boundary between the zone of accumulation and the zone of wastage is called the

A) wastage line.
B) accumulation line.
C) glacial line.
D) snowline.

Question 68

What were the desert valleys of the Great Basin like 17,000 years ago? What does the distribution of the ice-age lakes in the Great Basin reveal about the climate 20,000 years ago? How do we reconstruct ancient climate in this region? Where was the southerly track of northern winter storms during this time period?

Question 69

Most glacial ice originates as

A) fluffy snow.
B) sea water.
C) hard ice.
D) soft ice.

Question 70

What is the definition of a glacier?

Question 71

What are some ways that ice sheets modify the landscape?

Question 72

Crevasses in glaciers form by ________ deformation.

A) plastic
B) elastic
C) brittle
D) glacial

Question 73

Name three features of North America during the Last Ice Age.

Question 74

Ice moves ________ in the zone of accumulation and ________ in the zone of wastage.

A) downslope, upslope
B) downslope, downslope
C) upslope, downslope
D) upslope. upslope

Question 75

The snowline is ________ at high latitudes where year-round temperatures are ________.

A) lowest, cooler
B) lowest, warmer
C) highest, cooler
D) highest, warmer

Question 76

The wobble in Earth's rotational axis undergoes a periodic variation every

A) 12,000 years.
B) 23,000 years.
C) 41,000 years.
D) 100,000 years.

Question 77

Judge the following sentence according to the criteria given below. Glacial ice flows because if forms by metamorphism.

A) The assertion and the reason are both correct, and the reason is valid.
B) The assertion and the reason are both correct, but the reason is invalid.
C) The assertion is correct but the reason is incorrect.
D) The assertion is incorrect but the reason is correct.
E) Both the assertion and the reason are incorrect.

Question 78

Name the five landforms particularly distinctive of the current or former action of valley glaciers. Which one is depositional?

Question 79

A glacier undergoes ________ deformation in its upper part and ________ in its lower part.

A) plastic, brittle
B) plastic, plastic
C) brittle, plastic
D) brittle, brittle

Question 80

The interiors of glaciers are made up of ice that is

A) soft and compact.
B) hard and compact.
C) soft and porous.
D) hard and porous.