Download Chapter 21 The Geology of the Paleozoic Era

180
Chapter
21
The Geology of the Paleozoic Era
GUIDED STUDY
The text chapter should be studied one section at a time.
Before you read, preview each section by skimming it,
noting headings and boldface items. Then read the
appropriate section objectives from the following
outline. Keep these objectives in mind and, as you read
the chapter section, search for the information that will
enable you to meet each objective. Once you have
finished a section, write out answers for its objectives.
The Divisions of the Paleozoic (pp. 425-427)
1. Explain how the base of the Cambrian System has
changed from its original definition.
2. Explain how the Carboniferous System relates to
the Mississippian and Pennsylvanian systems of the
United States.
A Global Perspective (pp. 427-432)
5. Explain the reasons for extreme aridity on the
supercontinent of Pangaea during the Late Permian
Period.
North America in the Paleozoic (pp. 432-447)
6. Discus the events that built the Taconic Mountains
during the early Paleozoic, and the landforms that
resulted from their erosion.
7. What landmasses were involved in the Caledonian
orogeny?
8. Discuss the origin and significance of the Catskill
clastic wedge.
3. Describe the formation of the massive continent of
Gondwana.
4. Discuss the events that led to the assembly of the
supercontinent of Pangaea.
9. List the provinces of the Appalachian mountain belt,
and the deformation experienced by each.
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181
10. Describe the tectonic events associated with the
Antler orogeny.
The Divisions of the Paleozoic (pp. 425-427)
4. The time of “ancient life” has been named
the_______________ Era, which is the firt era of
the Phanerozoic Eon.
5. The first (lowest) appearance of easily visible
fossils marked the beginning of the _____________
11. List the four transgressive-regressive sequences that
migrated across the craton during the Paleozoic.
What type of boundary exists at the top of each?
Period. Its boundary has subsequently been lowered
to include both small shelly fossils and the
occurrence of complex, branching _____ ________.
6. The overlying _______________ System was
named for a tribe of ancient Welsh inhabitants.
7. The next time interval is the __________ Period,
also named for ancient Welsh peoples.
8. The geologic time period named for Devon County
12. Discuss the origin, sedimentary sequences, and
economic products associated with cyclic
sedimentation of the Pennsylvanian Period.
in southern England is the __________ Period.
9. The world outside the United States recognizes the
_________________ System, named for the coalbearing strata of England.
10. In the United States, strata that are roughly time
equivalent to the lower part of this sequence are
assigned to the _______________ Period, whereas
strata in the upper part belong to the
CHAPTER REVIEW
When you have finished reading the chapter, work
through the material that follows to review it. Complete
the sentences. As you proceed, evaluate your
performance for each section by consulting the answers
on pages 188. Do not continue with the next section
until you understand each answer. If you need to, review
or reread the appropriate section in the textbook before
continuing.
Introduction (p. 425)
1. The Paleozoic Era began with a continuation of the
breakup of the supercontinent________________.
2. Quart-rich sands began the _______________ that
eventually covered most of the North American
craton in the Ordovician Period.
3. A series of continental collisions during the
Paleozoic culminated in the formation of the
supercontinent called _____________.
Copyright © Houghton Mifflin Company. All rights reserved.
_________________ Period.
11. The _______________ Period is named for a city in
central Russia. Its end marks a time of the greatest
extinction in all of Earth history.
A Global Perspective (pp. 427-432)
12. During the early Cambrian, landmasses containing
present-day South America, Africa, India Australia,
and Antarctica collided together to form the
massive continent of _______________.
13. North America, Greenland, and northern Great
Britain formed the continent of ____________.
14. _________, _________, and _________________
were the other major Cambrian landmasses.
15. The_________ ________ separated Laurentia from
Baltica.
16. The third step in the Wilson cycle is ___________.
182
17. The merging of Laurentia and Baltica formed the
larger continent of __________.
18. The northern margin of Gondwana merged with the
southern margin of Laurentia during the
____________ ________.
19. The continents of Siberia and Kazakhstania
29. The large size, interruption of equatorial oceanic
circulation, numerous mountain ranges, and cold
coastal currents produced a(n)_____ __________
on Pangaea.
30. Warm temperatures contribute to the dryness of a
region by inhibiting both coal formation and
collided during the Pennsylvanian to form the
______________. Both processes conserve carbon
________ _______________ of central Asia.
dioxide, which as a greenhouse gas heats up the
20. The collision of Baltica with Kazakhstania during
atmosphere even more.
the Permian caused the __________ ___________
North America in the Paleozoic (pp. 432-447)
and the suturing of these two continents.
31. Deposition of sediment over much of the North
21. Pangaea was formed by the collision of Laurasia
with Gondwana. The single ocean surrounding this
continent from pole to pole was called
_____________.
22. At the beginning of the Paleozoic, most major
continents were located near the__________, which
promoted warm climates.
23. Unrestricted circulation of oceanic waters between
the poles and the tropics produces polar regions that
are _________.
24. The warm, epeiric seas of the early Paleozoic were
ideal for the formation of ______________
25. During the Ordovician Period, Gondwana drifted
over the ______ ______, resulting in the formation
of large glaciers and a worldwide drop in ____
______.
26. Gondwanan glaciation is indicated by deposits of
__________ , and bedrock with glacial
_____________.
27. Periods of late Paleozoic glaciation involve the
balance of ________ ___________ in the
atmosphere.
28. Both limestone deposition and periods of ______
_________ remove carbon dioxide from the
American craton built the ________________
___________.
32. Deformation of the eastern margin of North
America throughout the Paleozoic built the
_____________ ____________.
33. Small microcontinents or displaced terranes collide
or accrete to the continental margin in a process
called _________.
34. Mountains resulting from continental collisions
were quickly eroded, forming thick _________
___________.
35. The collision of North America with the Avalonia
terrane occurred during the _______ ________ of
Middle Ordovician age.
36. Erosion of the Taconic Mountains during the Late
Ordovician and Early Silurian periods produced a
thick sediment deposit called the______________
______ _________.
37. The collision of Laurentia and Baltica occurred
during the ____________ ________of Late Silurian
to Early Devonian age.
38. The suturing of Laurentia with ________ formed
the continent of Laurasia.
39. Erosion of the Caledonian Mountains produced a
atmosphere, possibly triggering episodes of
thick clastic wedge known in England as the _____
glaciation. Volcanic activity from rifting and
____ ____________.
subduction, returns carbon dioxide to the
atmosphere.
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183
40. In the Early to Middle Devonian, the remainder of
Avalonia docked with Laurasia during the________
_________.
41. The erosion of the Acadian Mountains formed a
massive sedimentary deposit known as
the________ ________ _________.
42. The Catskill Mountains of New York were formed
by sediments eroded from the Acadian mountains,
and stand as a prominent tableland because of their
resistant sandstones and ________________.
43. The Late Paleozoic collision between Laurasia and
Gondwana is called the ______________
__________.
44. Allegeheny deformation was different in each of
three distinct structural provinces. In the
__________ province, rocks were metamorphosed
and intruded because of their proximity to the
collision.
54. The top of such a sequence is defined by the
occurrence of a widespread, erosional
______________.
55. The first cratonic sequence is called the _____
___________. It covered most of North America
with shallow seas.
56. The basal rock formation of the _____________
__________ is the St. Peter Sandstone.
57. Deposits of the __________ ___________ consist
mainly of widespread, platform carbonates.
58. Erosion of tectonic highlands during the _________
__________ produced mainly terrestrial and
marginal marine deposits.
59. Final regression at the end of the Permian left
continental conditions across the entire _______.
60. Sedimentary sequences that contain an orderly,
repetitive alternation of depositional environments
are called _____________.
61. The pattern of deposition in an individual cyclothem
results from _____________ and ____________.
62. Burial of vegetation on marshy coastal plains by
marine sediments resulted in the production of
Pennsylvanian _______.
63. The frequency of cyclothems suggests an individual
cycle represents about ________years.
64. The cause of these cycles appears to be the growing
and shrinking of____ ________ in Gondwana.
45. In the ______ _______ province, Late Proterozoic
rocks were thrust cratonward along huge faults.
46. In the _________ ____ _______ province, strong
folding and faulting occurred at the surface, while
little deformation occurred at depth.
47. Late Paleozoic suturing of Gondwana and Laurasia
along the southern margin of North America and
PRACTICE TESTS
After you thoroughly understand the correct answers of
the Chapter Review, answer the following questions and
check them with the answers on pages 188-189. If your
answer is incorrect, consult the appropriate pages of the
text (in parentheses following the correct answer).
Multiple Choice Questions
the northern margin of South America occurred in
the _________ _________.
48. For most of the Paleozoic, the western portion of
North America was a _______ ______.
49. Subduction between the Klamath arc and the
western margin of North America resulted in their
collision by Late Devonian times, an event called
the _______ ________.
50. Deep-ocean sediments between the arc and the
continent were _______ eastward over the
continental shelf as much as 100 miles.
51. Uplift of crustal blocks along high-angle faults in
the cratonic interior formed the _______ ________
52. The stratigraphic record of North America contains
a series of transgressive-regressive cycles that are
called ________ ___________.
53. The base of each transgressive sequence is
indicated by the deposition of ________ _______.
Copyright © Houghton Mifflin Company. All rights reserved.
Circle your answers to the following questions.
1. During the early Paleozoic, tropical lands include:
a. Greenland.
b. India.
c. Africa.
d. South America.
2. The appearance of easily visible fossils defines the
beginning of the:
a. Precambrian interval.
b. Paleozoic Era.
c. Mesozoic Era.
d. Cenozoic Era.
3. The system that was described from southern
England was the:
a. Cambrian System.
b. Ordovician System.
c. Silurian System.
184
d. Devonian System.
4. The system described from central Russia was the:
a. Carboniferous System.
b. Permian System.
c. Pennsylvanian System.
d. Mississippian System.
5. The largest early Paleozoic continent was called:
a. Siberia.
b. Laurentia.
c. Gondwana.
d. Baltica.
6. Laurentia and Baltica were separated by the:
a. Atlantic Ocean.
b. Iapetus Ocean.
c. Pacific Ocean.
d. Panthalassa Ocean.
7. Laurentia and Baltica were soon joined to form:
a. Asia.
b. Gondwana.
c. Pangaea.
d. Lauraisa.
8. The Late Paleozoic collision between Baltica and
Gondwana occurred in the:
a. Hercynian orogeny.
b. Uralian orogeny.
c. Altai orogeny.
d. None of the above.
9. At the end of the Permian Period, the single ocean
surrounding Pangaea was called the:
a. Iapetus Ocean.
b. Pacific Ocean.
c. Panthalassa Ocean.
d. Atlantic Ocean.
10. Paleozoic ice ages resulted from:
a. large landmasses located in the southern polar
region.
b. removal of carbon dioxide from limestone
formation.
c. removal of carbon dioxide from coal formation.
d. All of the above.
11. Extreme aridity in the late Permian Period resulted
from:
a. a single large, wide landmass extending from
pole to pole.
b. removal of carbon dioxide from limestone
formation.
c. removal of carbon dioxide from coal formation.
d. All of the above.
12. The Appalachian and Ouachita mountains were
formed during the Paleozoic as a result of:
a. continental rifting.
b. continental collisions.
c. continental drifting.
d. passive margin deposition.
13. In the Taconic orogeny, Laurentia collided with:
a. Baltica.
b. Siberia.
c. Avalonia.
d. Gondwana.
14. The Queenston clastic wedge was derived from
erosion of which mountains?
a. Taconic
c. Caledonian
b. Acadian d. Rockies
15. The collision and suturing of Baltica and Laurentia
occurred during this orogeny:
a. Taconic orogeny.
b. Caledinian orogeny.
c. Acadian orogeny.
d. Hercynian orogeny.
16. The Catskill clastic wedge was derived from the
erosion of which mountains?
a. Taconic
b. Rockies
c. Catskill
d. Acadian
17. The environment of deposition represented by the
much of the Catskill clastic wedge was:
a. deep marine turbidites.
b. shallow marine shelf.
c. broad alluvial plain and floodplain.
d. volcanic highlands.
18. Deformation during the Allegeheny orogeny was
most severe in which tectonic province?
a. Piedmont province
b. Blue Ridge province
c. Valley and Ridge province
d. Plateau province
19. The Ouachita orogeny of Late Paleozoic age
resulted from collision of the southern margin of
North America with the northern margin of:
a. Africa.
b. South America.
c. Siberia.
d. Asia.
20. Western North America during the early Paleozoic
experienced:
a. continental collision.
b. continental rifting.
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185
c. subduction.
d. sedimentation on a passive margin.
True or False Items
Write true or false on the line in front of each statement.
21. Accretion of the Klamath arc onto the western
margin of North America was a result of the:
a. Acadian orogeny.
b. Antler orogeny.
c. Klamath orogeny.
d. Taconic orogeny.
22. The Ancestral Rockies were formed from highangle faults that relieved stress caused by the:
a. Allegeheny orogeny.
b. Antler orogeny.
c. Ouachita orogeny.
d. Acadian orogeny.
23. Erosion of the Ancestral Rockies produced
deposition of great thicknesses of feldspar-rich
sands and gravels, indicating that these mountains
were composed of:
a. basaltic lavas.
b. plutonic granites.
c. shallow-water limestones.
d. glacial tillites.
24. In the four trangressive-regressive sequences that
can be traced across the North American initial
sedimentary layer of each sequence is composed
craton, the of:
a. quartz-rich sands.
b. lime muds.
c. organic-rich clays.
d. glacial tills.
25. The top of each transgressive-regressive sequence is
represented by:
a. a volcanic ash layer.
b. quartz-rich sands.
c. a flow of basaltic lava.
d. an erosional surface or unconformity.
26. The transgressive phase of each cratonic sequence
covered most of North America except for a part of
the Canadian Shield and the:
a. Rocky Mountains.
b. Appalachian Mountains.
c. Transcontinental Arch.
d. Sierra Nevada.
27. The major energy resource produced from
Pennsylvanian cyclothem deposition is:
a. natural gas
b. coal.
c. oil.
d. tar sands.
Copyright © Houghton Mifflin Company. All rights reserved.
_____ 1. The world of the very early Paleozoic Era
was already well populated with plants and
animals similar to those of today.
_____ 2. The Cambrian System includes all of the
rocks deposited during the Cambrian Period.
_____ 3. The last Paleozoic system is the
Pennsylvanian System.
_____ 4. The massive continent of Gondwana was
already assembled before the beginning of
the Paleozoic Era.
_____ 5. The most important step in the assembly of
Pangaea was the suturing of Laurasia with
Gondwana.
_____ 6. Siberia and Kazakhstania were the first
continents to be joined together to eventually
form Pangaea.
_____ 7. Paleozoic ice ages were restricted to the
northern parts of Pangaea.
_____ 8. The Late Permian warmth resulted from the
natural burning of coal deposits formed
earlier in the Pennsylvanian Period.
_____ 9. The collisions that built Pangaea were
responsible for building the Appalachian and
Ouachita mountains of North America.
_____ 10. The closure of the Iapetus Ocean came about
by the suturing of several terranes to the
eastern margin of North America.
_____ 11. Sediments eroded from the Taconic
Mountains filled the Appalachian forelandbasin as the Catskill clastic wedge.
_____ 12. The Blue Ridge structural province is famous
for enormous thrust faults.
_____ 13. Tectonic activity in Western North America
was already present in the Cambrian Period.
_____ 14. Cratonic sequences end with an erosional
surface.
_____ 15. The Sauk sequence begins with Cambrian
sandstones.
_____ 16. The Tapeats Sandstone is oldest in the
eastern part of the Grand Canyon.
_____ 17. The base of the Tippecanoe sequence in the
midwestern United States begins with the
St. Peter Sandstone.
_____ 18. Evaporite deposition occurred in the
interior of the Michigan basin during
the Kaskaskia sequence.
_____ 19. Final transgression in the Late Permian
resulted in widespread deposition of
continental redbeds in the
southwestern United States.
_____ 20. Coal formation occurs during the regressive
phase of cyclothem deposition.
186
Essay Questions
Write a brief essay on a separate sheet of paper
answering each of the following questions.
1. List and describe the tectonic events responsible for
the assembly of Pangaea.
2. List the structural provinces of the Appalachian
Mountains, and describe the tectonic events that
occurred in each.
3. Explain the concept of a cratonic sequence, and list
the succession of sediments encountered.
4. What is a cyclothem, and what events were
responsible for their formation?
CHALLENGE TEST
8. During the Hercynian orogeny, the northern portion
of Gondwana converged with _________ _______.
9. The Uralian orogeny brought together ________
and ________________ as the final event in the
assembly of Pangaea.
10. The warm ______ seas of the early Paleozoic were
ideal for limestone deposition.
11. Burial of organic matter as coal removes carbon
dioxide from the atmosphere, triggering ______
____________.
12. Aridity in the Late Permian served increase
temperatures, because a lack of weathering and coal
Answer these questions the day before an exam as a
final check on your understanding of the chapter’s terms
and concepts. Check your responses with the answers on
pages 189-190. If your answer is incorrect, consult the
appropriate pages of the text.
formation on land left excess ________ _______ to
buildup in the atmosphere and raise global
temperatures.
13. As the continental collisions of North America with
Completion
Fill in the correct answers.
1. During the very early Paleozoic, ______________,
Avalonia and Baltica occurred, the building of the
________________ _____________ began.
14. Sediments shed from both the Taconic and Acadian
_______________, and ____________________,
mountains were deposited westward as clastic
were located in the tropical latitudes.
wedges in the Appalachian ______________.
2. The Paleozoic Era began with the ___________ of
Rodinia, and ended with the ___________ of
Pangaea.
3. The Paleozoic Era was originally defined by the
first appearance of easily visible _____________.
4. The Mississippian System was defined from
exposures in the______________ ______ _____
15. The Allegeheny orogeny was the climactic event in
the mountain-building of the Appalachians, when
_____________ collided with Gondwana.
16. The Ancestral Rockies formed as a byproduct of
stresses from the __________ orogeny.
17. Pennsylvanian coal formation occurred primarily
on the __________ half of the North American
craton.
Multiple-Choice Questions
and the Pennsylvanian System from exposures in
_______________.
5. East Gondwana contained the modern continents
of__________ and _______ ____________.
6. The Iapetus Ocean separated __________ from
______________.
7. Laurasia and Gondwana were joined together in the
Late Paleozoic by collision between the eastern
Circle the correct answer.
1. At the beginning of the Paleozoic, the Wilson cycle
in North America was:
a. continental collision. c. continental drifting.
b. continental rifting.
d. subduction.
2. The major divisions in the geologic time scale were
originally defined by:
a. major tectonic events. c. sea level change.
b. major climate events. d. fossil record change.
margin of North America and the northwestern
margin of _________.
3. The Carboniferous System of England was named
for strata that were:
a. iron-bearing.
c. fossil-bearing.
Copyright © Houghton Mifflin Company. All rights reserved.
187
b. diamond-bearing
d. coal-bearing.
4. This geologic Period experienced the greatest
episode of biologic extinction in Earth History:
a. Devonian.
c. Permian.
b. Mississippian.
d. Pennsylvanian.
5. At the beginning of the Paleozoic Era, Rodinia had
fragmented into:
a. two continents.
c. four continents.
b. three continents.
d. six continents.
6. At the end of the Paleozoic Era, tectonic activity
had assembled:
a. two continents.
c. four continents.
b. one continent.
d. six continents.
7. The Ural Mountains of Russia formed in the:
a. Ordovician Period.
c. Permian Period.
b. Silurian Period.
d. Devonian Period.
8. Sea level rise in the Cambrian was a result of:
a. accelerated activity at mid-ocean ridges.
b. melting of ice sheets.
c. building of ice sheets.
d. erosion of mountains formed by continental
collisions.
9. The position of Pangaea astride the equator in Late
Permian time drastically affected climate by:
a. controlling oceanic circulation.
b. melting southern ice sheets.
c. building northern ice sheets.
d. building equatorial ice sheets.
10. Tectonic activity on the craton of North America
involved:
a. mountain-building along the eastern margin.
b. mountain-building along the western margin.
c. sediment deposition over the central area.
d. all of the above.
11. The Taconic Mountains were formed during the
Early Paleozoic as a result of:
a. continental rifting.
b. continental collisions.
c. continental drifting.
d. microcontinent accretion.
12. In the Acadian orogeny, Laurasia collided with:
a. Baltica.
b. Siberia.
c. the remnants of Avalonia.
d. Gondwana.
13. Thickness of the Catskill clastic wedge is estimated
to be:
a. 4000 meters.
c. 1000 kilometers.
Copyright © Houghton Mifflin Company. All rights reserved.
b. 9000 meters.
d. 2000 kilometers.
14. The orogeny with the greatest extent of deformation
is:
a. Taconic.
b. Acadian.
c. Caledonian.
d. Allegeheny.
15. The Appalachian structural province that
experienced the least deformation during the
Allegheney orogeny was the:
a. Piedmont.
c. Plateau.
b. Blue Ridge.
d. Valley and Ridge.
True or False Items
Write true or false on the line in front of each statement.
_____ 1. Four major transgressions and regressions
occurred in North America during the
Paleozoic Era.
_____ 2. The Mississippian System is not recognized in
the United States.
_____ 3. The opening of the Iapetus Ocean in theEarly
Paleozoic began the formation of the
Appalachian mountain belt.
_____ 4. The Ural Mountains today form the
physiographic boundary between Europe and
Asia.
_____ 5. Pangaea was surrounded by a single ocean
called Tethys.
_____ 6. Gondwana covered the South Pole during the
Ordovician Period.
_____ 7. Widespread glaciation causes carbon dioxide
levels to drop.
_____ 8. The interior of Pangaea was dry during the
Late Permian age.
_____ 9. The Ouachita Mountains formed along the
southern margin of North America.
_____10. The Taconic orogeny involved the collision
between Laurasia and Baltica.
_____11. Erosion of the Caledonian orogen produced
the clastic wedge called the Old Red
Sandstone.
_____12. Redbeds of the Catskill clastic wedge
represent arid desert environments.
_____13. The Piedmont structural province is famous
for enormous thrust faults.
_____14. The Ancestral Rockies represent accretion of a
volcanic arc onto the western margin of
North America.
188
ANSWERS
CHAPTER REVIEW
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
Rodinia
transgression
Pangaea
Paleozoic
Cambrian; trace fossils
Ordovician
Silurian
Devonian
Carboniferous
Mississippian; Pennsylvanian
Permian
Gondwana
Laurentia
Siberia; Baltica; Kazakhstania
Iapetus Ocean
collision
Laurasia
Hercynian orogeny
Altai Mountains
Uralian orogeny
Panthalassa
equator
ice-free
limestone
South Pole; sea level
tillite; striations
carbon dioxide
coal formation
arid climate
weathering
continental platform
Appalachian Mountains
docking
clastic wedges
Taconic orogeny
Queenston clastic wedge
Caledonian orogeny
Baltica
Old Red Sandstone
Acadian orogeny
Catskill clastic wedge
conglomerates
Allegeheny orogeny
Piedmont
Blue Ridge
Valley and Ridge
Ouachita orogeny
passive margin
Antler orogeny
thrust
Ancestral Rockies
cratonic sequences
quartz-rich sands
unconformity
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
Sauk sequence
Tippecanoe sequence
Kaskaskia sequence
Absaroka sequence
craton
cyclothems
transgression;regression
coals
400,000
ice sheets
PRACTICE TESTS
Multiple-Choice Questions
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
a
b
d
b
c
b
d
a
c
d
a
b
c
a
b
d
c
a
b
d
b
c
b
a
d
c
b
True or False Items
1. False. The earliest Paleozoic landscape was entirely
barren of plants and animals.
2. True.
3. False. The last Paleozoic system is the Permian
System.
4. False. East and west Gondwana did not collide to
form Gondwana until the Middle Cambrian.
5. True.
6. False. Siberia and Kazakhstania were the last
continents to be joined to form Pangaea.
7. False. Paleozoic ice ages were most common in the
southern continent of Gondwana during the
Paleozoic Era.
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189
8. False. The late Permian warmth came from several
factors, including the positioning of Pangaea on the
equator, its great width, the loss of environments for
limestone production, and the loss of chemical
weathering due to reduced precipitation.
9. True.
10. True.
11. False. The erosion of the Taconic Mountains filled
the Appalachian foreland-basin with the Queenston
clastic wedge.
12. True.
13. False. Tectonic activity did not begin in western
North America until the Late Devonian Period.
14. True.
15. True.
16. False. Since the Cambrian craton was located far to
the east of the present-day Grand Canyon, the
Tapeats Sandstone of the western Grand Canyon
region was deposited earlier, and as the Cambrian
seas transgressed eastward, the Tapeats Sandstone
of the eastern Grand Canyon region was deposited
later, nearer to the craton.
17. True
18. False The Williston Basin was an active site of
evaporite deposition during the Kaskaskia
sequence.
19. False Final regression of the seas in Late Permian
time brought on widespread deposition of
continental redbeds throughout the southwestern
United States.
20. True
Essay Questions
1. The assembly of Pangaea involved four major
continental collision events:
a. The assembly of Gondwana in Middle Cambrian
time resulted from the collision of East and West
Gondwana.
b. The assembly of Laurasia in Late Silurian time
resulted from the collision of Laurentia and Baltica.
c. The initial assembly of Pangaea resulted from
the collision of Gondwana and Laurasia during the
Late Paleozoic.
d. The final assembly of Pangaea occurred as
Siberia collided with Kazakhstania during the
Pennsylvanian Period, and Baltica collided with
Kazakhstania during the Permian Period. The
resulting supercontinent stretched from pole to pole,
and contained virtually all land masses.
2. The Appalachian Mountains were built by four
major orogenies in the last one billion years, but the
Allegeheny orogeny has left the most dramatic
structural changes. In the Piedmont province, which
was located closest to the site of continental
collision with Africa, intense metamorphism and
numerous intrusions greatly affected the already
deformed rocks. In the Blue Ridge province, great
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sheets of Proterozoic rocks were thrust eastward
towards the craton. In the Valley and Ridge
province, the great wedges of sediments shed into
the foreland-arc basins were folded and faulted In
the plateau province, the thinning distal basin
sediments were tectonically undeformed, and
represent shallow marine environments that contain
abundant fossils.
3. Rising sea levels across the craton of North America
from the east, south, and west left similar
sedimentary sequences (that could be correlated) as
they lapped upon the continental interior.
Eventually, most of North America except for a
portion of the Canadian Shield, and the islands of
the Transcontinental Arch was underwater.The
intial sedimentary deposit of such a sequence began
with quartz-rich sands eroded from the continental
interior. As sea level rose, these sediments were
repalced with deeper-water muds, and then offshore,
platform limestones. When sea levels fell, much of
the sedimentary thickness previously deposited was
removed by erosion, resulting in a widespread
erosional surface or unconformity.
4. Cyclothems are represented by the orderly,
repetitive alternation of sediments produced in a
succession of adjacent depositional environments.
In the eastern part of North America, thin sequences
of sediments of Pennsylvanian age shift back and
forth between basal nonmarine (stream and deltaic
sandstone, siltstones, and coal) to higher marine
(shallow marine shales and limestones) strata. Rise
and fall of sea level produced these changes, but the
frequency and rapidity with which these changes
occurred precludes any tectonic causes for
cyclothem formation. The existence of ice sheets in
Gondwana during this entire time interval provides
the best explanation. Nonmarine strata would result
from buildup of the glaciers and worldwide
lowering of sea level, and marine sediments would
follow the rise of sea level following the melting of
glaciers. When the ice sheets finally retreated in the
Permian Period, cyclothems disappeared.
CHALLENGE TEST
Completion
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Canada; Greenland; Siberia
breakup; assembly;
fossils
Mississippi River Valley; Pennsylvania
Africa; South America
Baltica; Laurentia
Africa
southern Baltica
Baltica; Kazakhstania
epeiric
global cooling
190
12.
13.
14.
15.
16.
17.
carbon dioxide
Appalachian Mountains
foreland-basin
Laurasia
Ouachita
eastern
Multiple-Choice Questions
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
c
d
d
c
d
b
c
a
a
d
d
c
b
d
c
True or False Items
1. True.
2. False. The Carboniferous System is not recognized
in the United States.
3. False. The closing of the Iapetus Ocean began the
tectonic processes responsible for the building of
the Appalachian Mountains.
4. True.
5. False. The single, large ocean surrounding the
supercontinent of Pangaea was called Panthalassa.
6. True.
7. False Widespread glacial episodes may result from
drastically lowered levels of carbon dioxide in the
atmosphere, but they do not cause them. Reduction
in limestone production and coal formation during
glacial episodes cause carbon dioxide levels to rise,
eventually causing the ice sheets to melt.
8. True
9. True
10. False. The Taconic orogeny involved the collision
of Laurentia and Avalonia.
11. True.
12. False. Redbeds of the Catskill clastic wedge
represent alluvial plains and stream floodplains, as
indicated by the abundant fossil plants they
contain.
13. False. The Piedmont structural province was
characterized by intense metamorphism and
numerous intrusions.
14. False. The Ancestral Rockies rose along high-angle
faults that formed because of stress from the
Ouachita orogeny.
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