Chapter 18 Glaciers and Glaciation

Earth: An Introduction to Physical Geology 18.1

Multiple-Choice Questions1)

The ________ is not the name of a Pleistocene glacial episode in North America. A)

Dakotan B)

Kansan C)

Illinoian D)

Nebraskan Answer :

A

2)

The ________ was the most recent Pleistocene glacial episode in North America. A)

Dakotan B)

Kansan C)

Indianan D)

Wisconsinan Answer :

D

3)

________ is one of the two, major flow mechanism in a glacier. A)

Basal slip B)

Crevassal slip C)

Frost heaving D)

Morainal sliding Answer :

A

4)

Where is the world's largest ice sheet located today? A)

Greenland B)

Russia, Siberia C)

Iceland D)

Antarctica Answer :

D

5)

Approximately how long ago did the last of the great North American ice sheets melt? A)

1500 yrs B)

1.5 million yrs C)

15,000 yrs D)

150,000 yrs Answer :

C

6)

________ has/have speeds comparable to those of a flowing alpine glacier. A)

Soil creep B)

Streams C)

Mudflows D)

Basaltic lava flows Answer :

A

7)

The bottom or downward tip of a crevasse marks the ________. A)

boundary between parts of the glacier moving by basal sliding and crevassal slip B)

boundary between the basal sliding and external flowage zones C)

bottom of the basal sliding zone D)

top of the internal deformation and flowage zone Answer :

D

8)

Which one of the following applies to a valley glacier that lengthens (extends its terminus downslope) over a period of many years?

A)

Wastage exceeds accumulation. B)

Accumulation exceeds wastage. C)

Accumulation and wastage are about equal. D)

none of the above Answer :

B

9)

Abrasion and plucking generally involve what part of a glacier? A)

the internal, flowage zone B)

the snout zone C)

the surface, brittle zone D)

the basal, sliding zone Answer :

D

10)

A ________ cross-valley profile is typical of canyons and valleys eroded and deepened by alpine or valley glaciers.

A)

U B)

Y C)

V D)

S Answer :

A

11)

________ are erosional features produced by valley/alpine glaciers. A)

Moraines B)

Cirques C)

Eskers D)

Drumlins Answer :

B

12)

A(n) ________ is a depositional feature composed of till and only associated with continental glaciation, not with alpine glaciers.

A)

till B)

outwash C)

solid rock D)

outwash deposit Answer :

C

Match the feature with the appropriate material.

A. till B. outwash C. solid rock

13)

________ moraine Answer :

A

14)

________ erratic Answer :

C

15)

________ cirque Answer :

C

16)

________ esker Answer :

B

17)

________ horn Answer :

C

18)

________ drumlin Answer :

A

19)

________ first developed the theory that small variations in the Earth-Sun distance were responsible for short term, climatic oscillations (1000 to 100,000 years).

A)

H. Goering B)

H. Marcee C)

G. Zukhov D)

M. Milankovitch Answer :

D

20)

The great, Southern Hemisphere glaciation that affected parts of Africa, South America, India, Australia, and Antarctica occurred ________.

A)

in late Paleozoic time B)

in late Proterozoic time C)

in early Cenozoic time D)

in middle Mesozoic time Answer :

A

21)

Which of the following glacial features would typically be found in close proximity? A)

cirque and terminal moraine B)

outwash plain and horn C)

hanging valley and truncated spur D)

drumlin and fiord Answer :

C

22)

A(n) ________ represents a former meltwater channel or tunnel in glacial ice that was filled with sand and gravel.

A)

esker B)

yazoo ridge C)

valley plain D)

kettle Answer :

A

23)

What type of moraine would be most useful for tracing diamond-bearing kimberlite fragments directly to their bedrock source area?

A)

terminal, valley or alpine glacier B)

terminal, continental ice sheet C)

recessional, continental ice sheet D)

lateral, valley or alpine glacier Answer :

D

24)

Which one of the following samples and experimental measurements would provide the most information about the Earth's climate over the last 100,000 years or so?

A)

cores from sea ice in the Arctic Ocean; NaCl content B)

sediment cores from a terminal moraine in Ohio; sand-to-clay ratio C)

sediment cores from a Pleistocene loess deposit in the state of Mississippi; Si content D)

cores from the Greenland ice sheet; ratios of the oxygen isotopes (0-18/0-16) Answer :

D

25)

________ is the best explanation for a glacial surge. A)

The climate cools suddenly and a retreating glacier begins to advance B)

Heavy snowfalls resulting in avalanches in the zone of accumulation C)

Melting at the base of the glacier resulting in increased rates of basal slip D)

Crevasses opening suddenly near the snout of a glacier Answer :

C

26)

All of the following descriptions apply to stratified drift (not glacial till) except for ________. A)

deposited directly from melting ice B)

sand and gravel beds C)

deposits are often layered and well-sorted D)

deposited by glacial meltwater streams Answer :

B

27)

A(n) ________ is similar in appearance to a sinkhole of a karst area. A)

moraine B)

esker C)

cirque D)

kettle Answer :

D

28)

Which one of the following prominent landforms, located from the Wasatch Range, UT, westward to the Sierra Nevada, CA, formed during the Pleistocene glacial episodes?

A)

terminal moraines of continental ice sheets that moved south from Canada B)

old shorelines of large, pluvial lakes C)

erosional features produced by continental glaciation D)

subaerial deltas submerged by the post-glacial rise in sea level Answer :

B

29)

A fiord is ________. A)

a stream valley, deepened by glacial erosion, that floods as sea level rises B)

a glacier-cut valley that is dammed by an end moraine and a large lake is formed C)

a glacier-cut valley which sinks below sea level due to glacial rebound after the ice melts D)

a large, kettle-pocked moraine left as an island when sea level rises following melting of the ice

Answer :

A

30)

Which process occurs where a glacier enters the sea? A)

kaming B)

calving C)

surging D)

drowning Answer :

B

31)

The ________ of the geologic time scale represents the time of the most recent "Ice Age." A)

Pleistocene era B)

Pliocene epoch C)

Pleistocene epoch D)

Pliocene era Answer :

C

32)

Which of the following is the correct listing of the North American glacial stages from older to younger?

A)

Indianan, Kansan, Nebraskan, Ohioan B)

Kansan, Illinoian, Iowan, Dakotan C)

Nebraskan, Indianan, Illinoian, Wisconsinan D)

Nebraskan, Kansan, Illinoian, Wisconsinan Answer :

D

33)

Which one of the following statements concerning glaciers is not true? A)

Ice sheets are larger than ice caps. B)

Piedmont glaciers form on lowlands at the base of mountainous terrain. C)

The volume of water tied up in the Antarctic ice sheet is about the same as the total discharge of the Amazon River in one year.

D)

Long, extended, alpine glaciers occupied valleys in most high, mountainous areas in the United States, Canada, and Europe at one or more times during the past two million years.

Answer :

D

34)

A ________ is an erosional feature specifically produced by alpine glaciation. A)

lateral moraine B)

drumlin C)

crevasse spur D)

U-shaped valley Answer :

D

35)

A(n) ________ is likely to host a waterfall or steep rapids today. A)

outwash plain B)

hanging valley C)

striated drumlin D)

horn peak Answer :

B

36)

A ________ is a glacier-cut valley that partly flooded as sea level rose. A)

till crevasse B)

fiord C)

hanging cirque D)

kettle trough Answer :

B

37)

A drumlin is a ________. A)

smooth, tapering ridge of till; formed and shaped beneath a continental ice sheet B)

bowl-shaped depression eroded largely by frost action and glacial plucking C)

till mound of outwash deposited by meltwater streams at the snout of a glacier D)

smooth, striated, bedrock ridge shaped and polished by a glacier Answer :

A

38)

________ are both deposited by meltwater streams. A)

Terminal moraines and cirques B)

Outwash plains and valley trains C)

Valley moraines and ice sheet trains D)

Recessional kettles and erratics Answer :

B

39)

Where is the world's second largest continental ice sheet? A)

Iceland B)

Greenland C)

Antarctica D)

Siberian Russia Answer :

B

40)

How do icebergs in the North Atlantic Ocean originate? A)

by calving of large piedmont glaciers in Greenland B)

as large masses of sea ice that float northward from Antarctica C)

as masses of sea ice that float southward from the Arctic Ocean D)

as calved blocks of glacial ice that float northward from Antarctica Answer :

A

41)

Which of the following best describes the term glacial drift? A)

floating of icebergs southward from the north polar seas B)

slow, plastic flow movement in the brittle zone of a glacier C)

the sedimentary materials outwash and till D)

the slow, southward advance of the continental ice sheets over Canada and North America during the Pleistocene

Answer :

C

42)

Which one of the following statements concerning glacial deposits is not true? A)

Till is deposited directly from the ice; outwash is deposited by meltwater streams. B)

Glacial erratics are blocks of rock that are too large for the glacier to move. C)

Tills are poorly sorted and the fragments are mostly angular. D)

Outwash is mainly stratified sand and gravel. Answer :

B

43)

What type of moraine is formed by the merging of two lateral moraines at a junction of two valley glaciers?

A)

medial B)

recessional C)

ground D)

kettle Answer :

A

44)

A ________ forms when stagnant, glacial ice melts after being buried by drift. A)

tarn B)

kettle C)

drumlin D)

pluvial delta Answer :

B

45)

Which one of the following could not have significantly affected climatic variations and advances and retreats of ice sheets during the Pleistocene epoch?

A)

movements of Earth's tectonic plates B)

variations in the Sun's energy output C)

precession of Earth's orbit D)

wobbling of Earth's rotational axis Answer :

A

46)

________ was a very large, pluvial lake in Utah during the Pleistocene Epoch. A)

Lake Caspian B)

Lake Aral C)

Lake Mead D)

Lake Bonneville Answer :

D

47)

A ________ would logically be situated next to a large end moraine or terminal moraine. A)

cirque B)

fiord C)

pluvial lake D)

outwash plain Answer :

D

48)

Which of the following is often associated with a cirque basin in high, mountainous terrain? A)

loon lake B)

kettle pond C)

tarn lake D)

arête pond Answer :

C

49)

________ is an irregular, usually thin till layer laid down by a retreating glacier. A)

Terminal moraine B)

Outwash blanket C)

Kame sheet D)

Ground moraine Answer :

D

50)

All of the following are thought to possibly contribute to the formation of glaciers except for ________.

A)

eccentricity B)

precession C)

comets D)

plate tectonics Answer :

C

18.2

Word Analysis QuestionsExamine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.

1)

A) drumlin B) cirque C) esker D) moraine Answer :

cirque

2)

A) horn B) arête C) lateral moraine D) drumlin Answer :

drumlin

3)

A) calving B) zone of accumulation C) melting D) zone of wastage Answer :

zone of accumulation

4)

A) truncated spur B) glacial trough C) hanging valley D) pater noster lake Answer :

pater noster lake

5)

A) drumlin B) kame C) kettle D) esker Answer :

drumlin

18.3

True/False Questions1)

When a glacier is retreating, the upstream ice is still moving forward toward the downstream terminus of the glacier.

Answer :

TRUE

2)

Crevasses are short, narrow cracks in the plastic flow zone of a glacier that alternately open and close as the ice flows along.

Answer :

FALSE

3)

The downstream end or snout of a glacier advances over periods of time during which ablation exceeds accumulation.

Answer :

FALSE

4)

Till is an unsorted sediment deposited directly from the melting glacial ice; stream action is not involved.

Answer :

TRUE

5)

The recessional moraine is the largest of many terminal moraines laid down by a retreating glacier.

Answer :

FALSE

6)

Melting and evaporation are two forms of ablative calving. Answer :

FALSE

7)

Fiords are glacier-cut valleys that flooded as sea level rose in post-glacial times. Answer :

TRUE

8)

A cirque represents an erosional feature formed in what was an important accumulation zone for snow and ice at the upstream head of a glacier.

Answer :

TRUE

9)

The volume of the Antarctic ice sheet is about equal to the total volume of ice in all alpine glaciers of the world.

Answer :

FALSE

10)

The Pleistocene epoch of geological time began about 6 million years ago. Answer :

FALSE

11)

Because ice floats on seawater, coastal piedmont glaciers seldom erode much below the elevation of sea level at the times the glaciers are active.

Answer :

TRUE

12)

The great, Southern Hemisphere glaciation left Jurassic tills on parts of South America, India, and South Africa.

Answer :

FALSE

13)

Rapid surge movements of the Earth's tectonic plates offer a convincing explanation for the advances and retreats of the Pleistocene ice sheets.

Answer :

FALSE

14)

Great Salt Lake in Utah is the shrunken, salty remnant of a much larger, Pleistocene, pluvial lake called Lake Bonneville.

Answer :

TRUE

15)

Arête, horns, and U-shaped valleys are erosional features carved from bedrock by glaciers. Answer :

TRUE

16)

Sand and gravel deposited by glacial meltwater streams are known as outwash till or stratified till.

Answer :

FALSE

17)

In the north-central United States, much of the land north of the Ohio and Missouri Rivers was covered by one or more of the Pleistocene ice sheets.

Answer :

TRUE

18)

Surges in glacial movement are probably related to unusually fast rates of basal sliding. Answer :

TRUE

19)

Rock flour consists of silt-sized, rock and mineral particles produced by glacial abrasion. Answer :

TRUE

20)

Eskers and kames are deposited by meltwater streams; they are composed of stratified sand and gravel.

Answer :

TRUE

21)

Drumlins are believed to represent deltas built into pluvial lakes by meltwater streams. Answer :

FALSE

22)

Eccentricity, obliquity, and precession are three factors involved in the Milankovitch astronomical explanation of why the Pleistocene continental ice sheets alternately grew and shrank in size.

Answer :

TRUE

18.4

Short Answer Questions1)

The upper 40 meters or so of a glacier is known as the zone of ________. Answer :

fracture

2)

Unusually rapid, forward movements of glaciers are called ________. Answer :

surges

3)

List the two, major mechanisms of glacial flow. Answer :

plastic flow; basal slip

4)

What term describes open fissures in the brittle, surface ice of a glacier? Answer :

crevasse

5)

What general term denotes wastage of a glacier? Answer :

ablation

6)

Bridal Veil Falls in Yosemite National Park is an example of a ________. Answer :

hanging valley

7)

Bowl-shaped depressions in bedrock at upstream ends of alpine glacial valleys are called ________.

Answer :

cirque

8)

The wobbling motion of a spinning object is known as ________. Answer :

precession

9)

During the Pleistocene glacial epoch, pluvial lakes were common in valley regions of what part of the United States?

Answer :

Basin & Range

10)

What is the name for the very large, pluvial lake that once existed in northwestern Utah? Answer :

Lake Bonneville

11)

________ are smoothly tapered, elongated hills of till shaped by an overriding, continental ice sheet.

Answer :

Drumlins

12)

What is the oldest, Pleistocene, glacial stage in North America? Answer :

Nebraskan

13)

A(n) ________ is a closed depression formed by melting of an ice block buried in a moraine or outwash plain.

Answer :

kettle

14)

A(n) ________ is a narrow, winding ridge composed of outwash deposited in a tunnel or channel cut into stagnant, glacial ice.

Answer :

esker

15)

Valleys deeply eroded by alpine glaciers have what characteristic, cross-valley profile? Answer :

U-shaped

16)

What term denotes a glacial valley that was partly flooded as sea level rose? Answer :

fiord

18.5

Critical Thinking QuestionsUse complete sentences, correct spelling, and the information presented in Chapter 18 to answer the questions below

1)

Would most features of alpine glaciation be preserved in the geologic record? Why or why not? What about continental glaciation?

2)

Glacial ice is very effective as an agent of erosion. How would you identify glacial sediments from alluvial (stream) sediments? Also, could certain glacial sediments be mistaken for alluvium?

3)

Briefly discuss the indirect effects of glaciation. Indicate whether such changes would occur in conjunction with glaciation or at some time later?

18.6

Visualization Questions1)

Label the zones of ice movement on the glacier in the diagram below.

Answer :

See figure 18.8 in chapter 18 of Earth, 9e

2)

Label the zone of accumulation and the zone of wastage on the diagram below.

Answer :

See figure 18.11 in chapter 18 of Earth, 9e

3)

On the blanks provided below, fill in the name of the labeled features that formed as a product of alpine glaciation.

Answer :

a) hanging valley b) arête c) horn d) tarn e) pater noster lake f) cirques

4)

Match the features on the illustration below to the correct answer for each one.

Answer :

a) C b) E c) D d) A e) F f) B