Download Student Book Activity, p. 89 Student Book Question, p. 92

• There is evidence that ice sheets (glaciation) once
covered southern Africa, India, Australia, and South
America (paleoglaciation). Wegener believed this
was proof that these continents were once located
close to Antarctica.
Wegener did not hypothesize that the earth's crust
consists of moving plates. This theory, sparked by
Canadian J. Tuzo Wilson and known as Plate
Tectonics, was not developed until 1968.
c) Why did most scientists of his day disagree with
his theory?
ANSWER: (p. 90) Wegener could not explain what
mechanism was powerful enough to move huge
continents.
Student Book Activity, p. 89
1. On the world map provided by your teacher, colour
and label the continents. Lightly shade in the
world's oceans.
ANSWER: Distribute a copy of TSP blackline master
p. D5 to each student. You may wish to refer students to
an atlas.
2. Each dot on the map in Fig. 10-1 represents the location
of an earthquake. Which statement best describes the
pattern of earthquake distribution?
a) evenly spaced
b) scattered
c) in lines and arcs
d) in separate groupings
ANSWER: The pattern of earthquake distribution is c) in
lines and arcs. Greater concentrations of earthquakes
occur along wider lines and arcs in the Andes, New
Zealand, Japan, and the Philippines.
3. On the world map provided by your teacher in question
1, use the pattern of earthquakes to draw lines
indicating where you think the boundaries between
the plates are located. Most of the earth-quakes
should take place at the edges of the plates. Since
some plate boundaries are not very active, you may
find it difficult to find the location of some boundaries,
but do your best. (Hint:You should end up with a
jigsaw pattern—irregularly-shaped pieces that fit
together.)
ANSWER: Answers will vary according to how students
interpret the distribution of earthquakes in Fig 10-1.
4. a) How many plates did you find?
ANSWER. Using the solid red lines, students should
be able to identify clearly five lithospheric plates: the
American, the African, the Eurasian, the Antarctic, and
the Australian-Indian. By referring to Figure 10-4,
students may be able to see the Nazca, the Cocos,
and the Philippine plates. Geologists have been able to
identify even smaller, more complex plate divisions that
denote the Arabian, the Somali and the Scotia plates
as well as the Great African Rift Valley. There are
about 20 plates, but not all are visible on a map of this
scale.
b) Compare your results with the results of three of
your classmates. Did they put their plate
boundaries in the same places? Why or why not?
ANSWER: Students' maps may show as few as five
or as many as eight plates. Boundaries of the major
lithospheric plates will be similar, but variations will
occur for the smaller, less obvious plates.
Student Book Question, p. 92
Where will Canada be located in the next few hundred million years?
ANSWER: Canada is located on the North American Plate.
It is moving in a westerly direction from the Eurasian plate.
The plate boundary that indicates this divergence is the
Mid-Atlantic Ridge. The Eurasian plate continues to pull
away at this oceanic rift valley. The Eurasian plate is
moving in an easterly direction; it will eventually collide
with the North American plate. For this to occur, the Pacific
plate, which is moving in a northwesterly direction, must be
destroyed under the Eurasian plate. Subduction is already
occurring along the boundary as demonstrated by the
earthquakes and volcanoes in the Aleutian, Kuril, and
Japanese Islands. Subduction of the Pacific plate under
the North American plate is occurring off Canada's west
coast. When Canada collides with Russia, a new chain of
mountains will likely occur. The plates will merge in the
.
same manner as the Europe and Asian plates merged to
form the Eurasian plate of today.
Student Book Questions, p. 93
CHECK YOUR UNDERSTANDING
1. What was probably the first evidence that led people
to think that the continents were once connected?
ANSWER: (p. 90) The apparent jigsaw fit of the continents
was likely the starting point for the theory of continental
drift. For example, the shapes of South America and Africa
seem to fit together.
2. a) What did Alfred Wegener mean by "continental
drift"?
ANSWER: (p. 90) Wegener suggested that all the
earth's land masses, which were in constant motion,
collided about 300 million years ago to form one supercontinent which he called Pangaea. About 200 million
years ago, Pangaea started to break up. The pieces
drifted in different directions to their present positions.
b) What proof did he have to support this theory?
ANSWER: (p. 91) Wegener believed he could prove
his theory for the following reasons:
• He saw the jigsaw fit between South America and
Africa (coastline fit).
• He found fossils of the same plants and animals on
both continents (fossil correlation).
• The Appalachian Mountains in North America are of
similar age and structure as mountains in Scotland
and Scandanavia (geologic similarities).
Chapter 10: Geologic History Answers/Resource List
123
3 . Explain the theory of plate tectonics.
ANSWER: (p. 90) The crust of the earth consists of about
20 (lithospheric) plates. Most plates comprise an ocean
and a continental land mass. The plates are moving over a
weak layer of hot rock several hundred kilometres below
the earth's surface (the asthenosphere). No one fully understands the forces that cause the plates to move over the
layer of hot rock. It is possible that the unequal distribution
of heat within the earth creates convection currents in the
upper mantle that cause the plates to move. This may be
the "mechanism" that eluded Wegener, and that makes the
theory of plate tectonics plausible.
ANALYZE AND APPLY
4 . Why are most earthquakes and volcanoes located
near plate boundaries?
ANSWER. (p. 88) Earthquakes and volcanoes occur near
plate boundaries because it is here that the plates move
in relation to each other.
The plates that make up the earth's crust are moving
at different speeds and in different directions. For example, the North American plate and the Pacific plate are
sliding past each other along the San Andreas Fault in
California. This causes many earthquakes in the area. The
South American plate and the Nazca plate are colliding;
the Nazca plate is subducting below the South American
plate. This creates volcanoes and earthquakes in the
Andes Mountains. The volcanoes that surround the
Pacific Ocean (Pacific Rim of Fire) are a result of the
collision of the Pacific Plate with several other plates
5 . "The movement of the earth's plates has been important to Canada." Explain.
ANSWER: (p. 92) The movement of the earth's plates has
shaped Canada in many ways. It has contributed to the
formation of a number of Canada's geological features. For
example, the Appalachian Mountains in the east and the
Western Cordillera in the west were formed by plates
bumping together. Plate movement also contributed to the
development of fossil fuels. Oil, gas, and coal deposits were
formed as a res ult of events that took place when
Canada's land mass was located in a tropical climate.
THINK AND COMMUNICATE
6. a) Write a newspaper article describing continental
drift that could have appeared when Wegener first
published his theory.
ANSWER:Your studen ts should be able to provide
several different approaches to this question. Here is
124 a sample of what you might expect:
124
Chapter 10: Geologic History Answers/Resource List
German Scientist Says Continents Drifting
GODHAVEN, GREENLAND—Scientist Alfred Wegener
yesterday announced his revolutionary theory of continental drift as he boarded ship to return to Germany.
He hypothesizes that about 300 million years ago, the
earth's continents were one supercontinent, which Dr.
Wegener calls Pangaea. He believes that about 200 million
years ago, the supercontinent of Pangaea started to break up,
and the pieces, or continents, drifted in different directions
to their present positions. Wegener declared that his con tinental drift theory accounts for the similarity of fossils
found on different continents. His new hypothesis, however, explains why the shapes of the continents on both
sides of the Atlantic Ocean appear to fit together like
pieces in a jigsaw puzzle.
Wegener said, "I feel confident that the correspon dence in the coastlines of the continents on both sides of
the Atlantic is proof that all the continents were once
joined together as one large land mass. The existence of
fossils and mountain ranges of the same age and structure
on opposite land masses is further proof. We know that ice
sheets once covered southern Africa, India,Australia, and
South America. How could this ice develop in places that
are so warm today? I am sure that at one time these land
masses were located very close to the South Pole. This
evidence will convince my colleagues of the truth of my
continental drift theory."
—August 12, 1913.
b) Write an editorial that either supports or rejects
his theory. Fully explain your reasons.
ANSWER: Students may write editorials that either
support or reject Wegener's theory. Here is an example
of one rejecting his theory.
Revolutionary Thinker or Raving Lunatic?
The theory that the continents were once pieces of one
large land mass that "drifted" apart was presented yesterday
by German scientist Alfred Wegener. Wegener says that
proof of this theory is that the coastlines on both sides of
the Atlantic Ocean look as if they once fitted together like
pieces of a jigsaw puzzle. He also stated that similar fossils
and mountain ranges found on both sides of the Atlantic
are also proof of his "continental drift" theory. Wegener
believes that the signs of glaciation in South America,
Africa, India, and Australia are further evidence that these
land masses were once close to Antarc tica.
We do not believe that Dr.Wegener's evidence is overwhelmingly convincing. His "jigsaw fit" of the continents
is far-fetched. Granted, there is a possible fit between South
America and Africa, but where else on the globe is this fit
obvious? A few similar rock samples from mountains on
both sides of the Atlantic and a selection of similar fossils
cannot support his theory that the earth's continents were
once one supercontinent. We suggest that it is entirely Student Book Questions, p.100
possible that two separate mountain ranges were formed of
the same rock at the same time on two different continents.
We also suggest that it is scientifically possible that the exact CHECK YOUR UNDERSTANDING
same animals and plants lived on each side of the Atlantic at 1. "The earth's physical landscape is the result of conflict
the same time.Wegener's theory of ice sheets in South
between forces .... " Explain what this means.
ANSWER: (pp. 93, 95) The earth's physical landscape is
America, Africa. India. and Australia is nonsense! Glaciers
partly the result of conflict between the forces that build
could simply have formed over these land masses during the
the land higher, and those that wear it down. Volcanoes,
last Ice Age. Lastly, but most importantly, can Dr. Wegener
folding, and faulting are the major forces that push the
tell us exactly how and why the continents drifted away from
land up to form mountains. Mountains, in turn, are slowly
and continuously worn down by wind, rain, running water,
one another over such huge distances% Can he explain the
ice, temperature changes, and chemical reactions. This
mechanism that caused such an incredible journey%We think
wearing down is called erosion. At different times and in
not.We urge Dr.Wegener to stick to the much more plausible
different places, one force has been stronger than the
land-bridge theory put forward by his respected scientific
other. Over millions of years, mountain ranges, plains, and
colleagues.
oceans developed and disappeared many times. This
conflict forms the story of the earth's geologic history.
The Editors.
Student Book Question, p. 93
How many times would the length of your life (a fifteenyear -old) fit into the earth's lifespan of 4 600 000 000
years?
ANSWER: 4 600 000 000 divided by 15 = 306 666 666.67
times
Student Book Activity, p. 94
1. Using the information from Fig. 10-6, answer the
questions below.
a ) How old is the earth?
ANSWER: (p. 96) The earth is 4 600 000 000 years old,
or four billion, 600 million years old (46 billion years old).
b)
c)
What percentage of the earth's age does each
era represent?
ANSWER: (Fig. 10-6, p. 94)
Cenozoic ((66 - 0)/4600) x 100 = 1.4%
Mesozoic (1245 -66)/4600) x 100 = 3.9%
Paleozoic ((570 - 245)/4600) x 100 = 71%
Precambrian (14600 - 570)/4600) x 100 = 876%
What is the name of the era in which we live?
ANSWER: (p. 94) We live in the Cenozoic era. York
University Professor Skid Crease says that we should
be entering a new era of caring for the environmental health of the planet He calls this era the
"Ecozoic".
2. a) Draw a line 25 cm long on a piece of paper. Divide it
into eras based on the percentages calculated in
question l b .
ANSWER: The completed time line should have
divisions at these intervals (from left to right): 0 cm to
21.9 cm (Precambrian); 21.9 cm to 23.7 cm (Paleozoic);
23.7 cm to 24.7 cm (Mesozoic); 24.7 cm to 25 cm
(Cenozoic).
b) Using the chart from Fig. 10 -6, label the main
geological events which occurred in each era
along the line.
ANSWER: (p. 94) Refer your students to Fig. 10 -6 for
major ge ological events corresponding to each era.
2. a) What part of Canada was created during the
Precambrian era?
ANSWER: (p. 95) The Canadian Shield was created
during the Precambrian era.
b ) What types of rock make up this landform?
ANSWER: (p. 95) The Canadian Shield is made of
igneous, metamorphic, and some sedimentary rock.
c) How did it differ in appearance from today?
ANSWER: (p. 95) The Canadian Shield was an enor mous mountain range taller than any that exists today.
At times, the peaks were as high as 12 000 m above
sea level. Now, most parts of the Canadian Shield are
less than 500 m high and form a peneplain.
3. Where was the eroded material from the Shield
deposited and what did this material become?
ANSWER: (p. 97) The eroded material or "sediments" from
the Shield (see Fig. 10-8) was moved by rivers and
deposited in shallow seas surrounding the Shield. Over
millions of years, these sediments were compressed into
layers of sed imentary rock to form the bedrock that today
underlies part of every province.
4. What was the most important geological event of the
Paleozoic era?
ANSWER: (p. 97) The most important geologic event of the
Paleozoic era was the creation of vast layers of sedimentary
rock that contained deposits of oil, gas, and coal. These
lay ers of sedimentary rock were made of sediments laid
down under shallow seas.
(p. 98) Students may also answer the question by
stating that the most important event was the formation of
Pangaea 300 million years ago and the formation of the
Appalachian Mountains.
5. Geologists believe that Canada was located closer to the
equator during the early part of the Paleozoic era. Why
has this tropical location been important to Canada?
ANSWER: (p. 97) Organisms (marine plants and animals)
that eventually produced the great oil and gas deposits of
western Canada lived in the warm shallow seas surround ing the ancient Canadian Shield. Huge swamps grew in
the warm climate of this tropical location. The vegetation
of these swamps eventually produced the coal -bearing
rock of Nova Scotia.
Warm, shallow, tropical seas were also responsible
for the formation of the coral reefs located thousands of
metres below the surface of the land in Alberta and
Saskatchewan. They contain deposits of oil and gas (see
p.106).
formed and then melted away, they dumped large
amounts of clay, silt, sand, and gravel on the lowlands
surrounding the Shield. The glaciers set the current pattern of Canada's lakes, rivers, hills, and plains.
Glaciers that moved across the face of North
America created examples of erosion and deposition:
Peggy's Cove in Nova Scotia has amazing erratics;
Labrador's coastline is characterized by deep fiords;
drumlin fields surround the cities of Peterborough and
Guelph; the Great Lakes and the lakes of the Canadian
Shield have been gouged out by glaciers; southern
Ontario's glacial till deposits are excellent for
agriculture; the Rockies are renowned for their alpine
valleys and finger lakes; Kluane, the largest non-polar
icefield in the world, is filled with alpine glaciers and
cirques; and Ellesmere, Axel Heiberg, Baffin and Devon
Islands in Nunavut are covered by the remnants of iceage glaciers.
6. Based on the fossil evidence, what life forms existed
during the Paleozoic era?
ANSWER: (p. 98) Living organisms (plants and animals) in
the seas, sea organisms with shells, simple plants, trees,
fish, insects, and amphibians existed during the Paleozoic
era. Fossils of crinoids, molluscs, and trilobites are found
in rock sam ples from this era.
7. What event marks the division between the Paleozoic
and Mesozoic eras?
ANSWER: (p. 98) The division between the Paleozoic and
Mesozoic eras is marked by the extinction of many plant
and animal species. Half the fossil group of organisms
found in the rocks of the late Paleozoic era are missing in
the rocks of the early Mesozoic era.
8. During the Mesozoic era, the North American Plate
collided with the Pacific Plate. What resulted from
this collision?
ANSWER: (p. 98) The Coast Range and Rocky Mountains
resulted from this collision in the following manner: the
collision caused huge amounts of magma to rise within a
few kilometres of the surface of the North American Plate.
It cooled and solidified into a large mass of granite. This
grani te structure was later uplifted and formed the Coast
Range Mountains. Towards the end of the Mesozoic era,
tremendous tectonic forces folded the earth's surface to
begin the formation of the Rocky Mountains. Large
amounts of volcanic material and the formation of mountains between the Coast Range and the Rockies add to
the complex geology of the Western Cordillera.
9. How were (i) coal and (ii) oil and gas deposits formed
in western Canada during the Mesozoic era?
ANSWER: (p. 98-99) The climate of the land mass that is
now Canada was still warm during much of the Mesozoic
era.
(i) When the vegetation growing in swamps died, it fell
into the water and was covered by sand and silt
(sediments). Over millions of years, layers of sediments
compressed the layers of vegetation to form coal deposits.
(ii) In the shallow seas that periodically covered the
Interior Plains, the remains of tiny sea creatures and
plants fell to the sea floor and were covered by
sediments. As the sediments piled up, they were
compressed into sedimentary rock. Bacteria, heat, and
pressure from the weight of the rock changed the plant
and animal remains into oil and gas (refer to p. 323 for
further explanation of these processes).
10. a) How many glacial periods have there been during
the last two million years?
ANSWER: (p. 99) There have been at least four periods of large-scale glacial activity during the last two
million years.
b) Describe the effects that glaciers have had on the
Canadian landscape.
ANSWER: (p. 99) The ac tions of glaciers were like giant
earth-moving machines. They scraped and gouged the
land they covered. The Appalachian Mountains and the
Canadian Shield were rounded by moving ice often
more than a kilometre in thickness. As the glaciers
ANALYZE AND APPLY
11. Most geologic events happen very slowly. What are
two geologic events that happen fast enough for
people to see?
ANSWER: Earthquakes and volcanic eruptions happen
quickly and suddenly enough for people to see.
12. What were the main geologic events that occurred in
the area of Canada where you live? In which era did
they occur? What evidence of these events can you
see?
ANSWER: Answers will vary according to where students
live. If students are not familiar with the features in their
immediate area, it may be appropriate to complete this
question after studying the next chapter on landform
regions.
Extension Activity 1: Folding and Faulting,
TSP blackline master pp. 130-131
STAGE 1
1.
In which direction is pressure being exerted? Where
does the pressure come from?
ANSWER: The stress is being exerted towards the middle
of the land area. The stress comes from slow -moving convection currents in the hot mantle beneath the earth's crust
STAGE 2
2.
What happens to the earth's crust as a result of this
pressure?
ANSWER: The earth's crust folds into a series of ridges.
The Rocky Mountains of the Western Cordillera and the
Appalachian Mountains are fold mountains.
3.
How are faults formed?
ANSWER: Faults are formed when stress causes rock to
move quickly. If the rock is brittle (like most of the rock on
the earth's surface) or the movement is too fast for the rock
to bend, a fracture (crack) will develop and move ment will
occur along it, producing a fault.
4.
Examine Stages 1 and 2. What has happened?
ANSWER: In Stage 1, stresses within the earth have caused
a fracture to occur in the rock layers (sedimentary rock is
used to demonstrate faulting because the layers
make displacement easy to see) One block is displaced
vertically in relation to the other block.
5.
6.
Imagine that you are a geologist examining the rocks
in the diagram. How could you prove that faulting has
occurred?
ANSWER: A geologist could prove that faulting has
occurred by examining the rock. The sedimentary rock
layers on either side of the fault-line have been displaced
vertically with respect to one another.
Using your own words, explain how a rift valley is
formed.
ANSWER: Tensional stress may cause two faults to develop
in the earth's crust. Under continued stress the middle portion may drop downward in relation to the land on either
side of the two faults producing a rift valley.
contain any crystals because the cooling process is so fast.
Any crystals that do form are very small. The resulting rock
has a fine texture.
Basalt is an extrusive igneous rock.
4.
Where in Canada are igneous rocks commonly found?
ANSWER: The Canadian Shield and the Coast Mountains
in British Columbia contain large amounts of igneous rock.
5.
Describe the process that forms sedimentary rock.
ANSWER: Sediments are carried into oceans where they
are deposited in horizontal layers. Over millions of years
the weight of the overlying layers compresses the sediments into sedimentary rock.
6.
What parts of Canada largely contain sedimentary
rocks and what minerals are found in them?
ANSWER: The Interior Plains, the Great Lakes St. Lawrence Lowlands, the Hudson Bay-Arctic Lowlands,
and the Rocky Mountains are composed primarily of
sedimentary rocks. These rocks also form portions of the
Apalachians and Innuitian Mountains. Sedimentary rocks
may contain coal, oil, natural gas, salt and potash.
7.
Describe how metamorphic rocks are formed.
ANSWER: Metamorphic rocks are formed when igneous or
sedimentary rocks are subjected to heat, pressure, and
certain fluids.
• Heat allows the chemical components of the rock to
recombine more easily.
• Pressure, created at great depths (such as 10 or more
kilometres) also allows the chemical components to
recombine easily.
• Fluids containing hot gases and chemical solutions
promote the recrystallization of rocks.
Extension Activity 2: The Rock Cycle, TSP
blackline master pp. 132-134
0.
In your notebook, complete the following chart.
Igneous/Sedimentary Rock
1. Why is the geologist's knowledge of rocks important
to some companies?
ANSWER: Mining companies and oil companies seek the
advice of geologists so they know where to search for the
mineral resources they require. Only certain types of rocks
may contain the minerals they are looking for and the
geologist can identify these types of rocks and the rock
structures that may contain the minerals. Without this
guidance, companies could waste time and money
searching for minerals in the wrong place.
2. Explain how intrusive igneous roc ks are formed,
describe their characteristics, and give an example.
ANSWER: When magma slowly cools deep within the
earth, large crystals develop. If it cools closer to the
surface, the cooling process is faster and the crystals are
smaller. The larger the crystals, the more coarse the
texture of the rock.
Granite is an example of an intrusive igneous rock.
3. Explain how extrusive igneous rocks are formed, describe their characteristics, and give an example.
ANSWER: Lava that cools very quickly on the earth's
surface forms extrusive igneous rock. The rock may not
1.
Metamorphic Rock
Limestone
becomes
Marble
Shale
becomes
Slate
Quartz sandstone
becomes
Quartzite
Granite
becomes
Gneiss
Without looking back at your notes, draw the rock
cycle. Begin with five boxes. Label each box. Draw
and label arrows between boxes to represent the
processes involved in the rock cycle.
English as a Second Language Activity, TSP
blackline master p. 135
A. 1. continental (adj.), 2. erosion (n.); 3. deposition (n.);
4. extinctions (n.); 5. volcanic (adj.); 6. sedimentary (add.);
7 metamorphic (adj.); 8. collision In.); 9. solidified (v); 10.
glaciation (n); glacial (adj.)
B. 1 continental; 2. erode; 3. deposit; 4. extinct;
5. Volcanic; 6. sediment; 7 Metamorphic; 8. collision; 9.
solidify; 10. glacial