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S.M.S. TOTI DAL MONTE
MOGLIANO VENETO
A.S. 2007/2008
PROGETTO COMENIUS – LINK
“CONTINENTAL DRIFT”
Classe 3^ L
Insegnanti: Sandra Zanoni (Scienze M.C.F.N.)
Lilia Biscuola (Inglese)
INTRODUCTION
This is a physical map of the world.
 How many continents are there? Name them.
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ACTIVITY 1
Put the correct name of the continent in each blank.
Word bank: Australia, South America, Europe, Asia, Africa, North America
QUESTIONS:
 Do you think the continents always looked as they do on the map?
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 Do you think they have changed shape or location throughout Earth’s
history?
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Now look at the animations:
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 Were you right or wrong?
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 What do you think it is about?
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 Can you describe what you have just seen?
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Read the following text:
CONTINENTAL DRIFT
In 1915, the German geologist and meteorologist Alfred Wegener first proposed the
theory of continental drift, which states that parts of the Earth’s crust slowly drift. He
hypothesized that there was a gigantic supercontinent 225 million years ago, which
he named Pangaea, meaning “All earth/land”. This huge supercontinent was
surrounded by one gigantic ocean called Panthalassa.
About 200 million years ago the supercontinent Pangaea began to break up. About
180 million years ago Pangaea broke into two new continents Laurasia and
Gondwanaland. The huge ocean of Panthalassa remained but the Atlantic Ocean
was going to be born soon with the splitting of North America from the Eurasian
Plate.
The fit of the continents and the distribution of fossils and rocks supported Wegener’s
theory. For example, rock sequences in South America, Africa, India, Antarctica and
Australia show remarkable similarities in age and mineral composition. Wegener
proposed that rock sequences were made when all the continents were part of
Pangaea. Thus, they formed in a smaller contiguous area that was later broken and
drifted apart. (see Activity 2)
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Fossils of the same species (Mesosaurus, Cynognathus, Lystrosaurus –reptiles- and
Glossopteris -a fern) were found on several different continents, too. Wegener
proposed that the species dispersed when the continents were connected. For example
Glossopteris, a fern, was found on the continent of South America, Africa, India and
Australia. (see Activity 3)
About 135 million years ago Laurasia was still moving, and as it moved it broke up
into the continents of North America, Europe and Asia (Eurasian plate).
Gondwanaland also continued to spread apart and it broke up into the continents of
Africa, Antarctica, Australia, South America, and the subcontinent of India. Arabia
started to separate from Africa as the Red Sea opened up. The Atlantic, Indian,
Arctic, and Pacific Oceans were all beginning to take shape as the continents moved
toward their present positions.
Notice the position of the Indian Subcontinent today. It moved hundreds of miles in
135 million years at a great speed. India crashed into the Eurasian continent with such
a speed and force that it created the tallest mountain range on Earth, the Himalayas!
The continents are still moving today making the Atlantic Ocean larger and the
Pacific Ocean smaller.
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GLOSSARY
a. Contiguous = next in order = contiguo, vicino
a.+ n. Continental drift = deriva dei continenti
v. To drift = to move passively = spostarsi lentamente
n. Fern = a plant = felce
n. Fit = matching = adattamento
a. Huge = enormous = enorme
n. Splitting = separation = separazione
v. To spread (apart) = to cover larger surface = espandersi
v. To state = to express = affermare
v. To surround = to be all round = circondare
prep. Toward/Towards = in the direction of = verso
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EXERCISES
1) Write if these sentences are true (T) or false (F). Correct the false ones.
o
o
o
o
o
Laurasia and Gondwanaland were giant continents
Pangaea began to break up 180 million years ago
The Atlantic Ocean was born by the break of America and Europe
Fossils did not support Wegener’s theory
Glossopteris was found in South Africa, India and Australia
2) Choose the right answer.
1. Wegener hypothesized that 200 million years ago:
o There were two gigantic supercontinents
o The continents were just like today
o There was a gigantic supercontinent
2. What did Laurasia break up into?
o The Eurasian continent
o Europe and Asia
o North America and the Eurasian continent
3. What did Gondwanaland break up into?
o Africa and Antarctica
o India and Asia
o Australia, Africa, India, Antarctica and South America
4. How were the Himalayas created?
o The Eurasian continent crashed into India
o India crashed into the Eurasian continent
o India moved towards Australia
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ACTIVITY 2
Materials:
- shapes of the continents
- glue
- cardboard
Procedure:
Here are the shapes of the continents
of the Southern hemisphere. Try to
piece
them
together
as
Gondwanaland. When you are sure
each piece is where you want, glue
them on the cardboard. Compare
your version of Gondwanaland with
the picture of what the scientists
believe Gondwanaland looked like.
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ACTIVITY 3
Materials:
- your version of Gondwanaland
- pictures of fossil organisms
- glue
- data chart
Procedure:
Using the data chart below, place a picture of each representative fossil on the
appropriate continent.
Data chart
Mesosaurus: freshwater swimming reptile found in Brazil and in Africa.
Cynognathus: large land reptile (9 feet long) found in Argentina,
Southern Africa, India and China.
Glossopteris: a seed fern found in South America, Africa, Madagascar,
India, Antarctica and Australia.
Lystrosaurus: a herbivorous reptile with a very distinctive skull shape,
found in Africa, India, Antarctica, Indochina, Western and Central
China.
Remember: China and Indochina are not included in Gondwanaland map!
GLOSSARY
n. Freshwater = water that is not salty = acqua dolce
n. Skull = part of skeleton corresponding to head = cranio
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Now compare your reconstruction with the map of fossil distribution made by
Wegener.
QUESTIONS
 Could these plants/animals have crossed the ocean?
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 Scientists have evidenced that Glossopteris was found in what is now
India, Antarctica, Australia, and Madagascar. What does this tell you
about Glossopteris? What does it tell you about the climate and
environment of Gondwanaland?
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 Mesosaurus is a freshwater swimming reptile found in Brazil and in
Africa. Do you think it could have crossed the Atlantic Ocean?
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Read the following text:
Wegener’s model was not accepted by all geologists, because he could not find
an adequate mechanism for moving the continents; in fact he could not explain what
kind of forces could be strong enough to move such large masses of solid rock over
such great distances.
A mechanism to move continents was proposed by Arthur Holmes in 1928;
later, during 1940s and 1950s, great advances were made in the knowledge of sea
floor and in the properties of rocks. These studies provided new evidences to support
continental drift.
In order to understand how continents can move, we need to know what is the
inner structure of the Earth.
LAYERS OF THE EARTH
The Earth is divided into three chemical
layers: the core, the mantle and the crust.
The core is composed of mostly iron and
nickel and remains very hot. The core is
divided into two layers: a solid inner core
and a liquid outer core. The middle layer
of the Earth, the mantle, is made of
minerals rich in the elements iron,
magnesium, silicon, and oxygen. The
crust is rich in the elements oxygen and
silicon with lesser amounts of
aluminium, iron, magnesium, calcium,
potassium, and sodium. There are two
types of crust.
Oceanic crust is made of relatively dense
rock called basalt. Continental crust is
made of lower density rocks, such as granite.
The outermost layers of the Earth can be divided by their physical properties
into lithosphere and asthenosphere. The lithosphere (from the Greek, lithos, stone) is
the rigid outermost layer made of crust and uppermost mantle. The asthenosphere
(from the Greek, asthenos, devoid of force) is part of the mantle that flows, a
characteristic called plastic behaviour. It might seem strange that a solid material can
flow. A good example of a solid that flows, or of plastic behaviour, is the movement
of toothpaste in a tube.
GLOSSARY
a. Devoid (of) = privo (di)
n. Evidence = proof = prova
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v. To flow = to move continuously = scorrere
n. Iron = silver-white metal = ferro
It might seem = potrebbe sembrare
a. Outermost = external = più esterno
a. + n. Plastic behaviour = comportamento plastico
n. + n. Sea floor = bottom of the sea = fondale
a. Uppermost = at the top = superiore
ACTIVITY 4
Match the name of each layer with the proper location. Specify if each layer is solid
or liquid.
Word bank: mantle, inner core, outer core, crust, lithosphere
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ACTIVITY 5
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Read the following text:
HOW CAN CONTINENTS MOVE?
The inner part of the Earth is very hot; this explains why the rocks of
asthenosphere have a plastic behaviour, i.e. they can flow. Many geologists think that
in the mantle there are very slow convection currents (only few cm per year): the
deepest material, that is very hot, rises, becomes cool, flows laterally and then falls.
(see Activity 6).
The rigid lithosphere seems to float over these convection currents.
Geologists have known for over a century that there is a ridge in the middle of
the Atlantic Ocean (Mid-Atlantic Ridge); it is an area of earthquakes and the rocks
near it are younger than the other rocks of the ocean floor. Moreover, they are much
younger than the rocks of the continents. Thus, in 1962 the geologist Harry Hass
proposed that new ocean floor is formed at the top of Mid-Ocean ridges. The ocean
floor, and the rocks beneath it, are produced by magma that rises from deeper levels.
(see Activity 7)
But, if new oceanic lithosphere is created at Mid-Ocean ridges, where does it
go?
Convection cells in the mantle help carry the lithosphere away from the ridge.
The lithosphere arrives at the edge of a continent, where it is subducted, that is it
sinks into the asthenosphere. Thus, oceanic lithosphere is created at Mid-Oceanic
ridges and consumed at subduction zones, areas where the lithosphere sinks into the
asthenosphere. (see Activity 8)
GLOSSARY
p. Beneath = under = sotto
v. To float = galleggiare
n. Ridge = dorsale
v. To sink = to disappear below the surface of a mass of water = affondare
v. To be subducted = essere subdotto (affondare sotto il mantello)
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ACTIVITY 6
Materials:
- a big beaker
- alcohol burner
- tripod and wire gauze
- cold water
- flour
- a tablespoon
Procedure:
- Half fill the beaker with cold water.
- Spread half tablespoon of flour over the water surface.
- Put the beaker over the tripod.
- Light the alcohol burner.
- Look at the water surface for some minutes: what can you see?
You can see circular motions inside the water. In fact the flame heats the water
at the bottom of the beaker; hot water is lighter than cold water, so it rises and moves
on the surface; cold water, that is heavier, falls, then moves on the bottom, heats and
rises again. In this way circular motions, called convection cells, are formed.
The material of asthenosphere acts just like water.
GLOSSARY
n. Tripod and wire gauze = treppiede e reticella spargifiamma
n. Flour = farina
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ACTIVITY 7
Materials:
- a wax candle
- a small beaker
- alcohol burner
- tripod and wire gauze
Procedure:
- Break the candle into small pieces.
- Put the pieces in the beaker.
- Light the alcohol burner.
- When the wax is melted, turn off the alcohol burner.
- Pour some cold water over the melted wax.
- Light the burner again: what can you see?
- When the wax is melted again, turn off the burner.
When the wax is very hot, it changes into gas and produces bubbles. They
quickly go up, cross the wax crust and create “volcanoes”.
The lithosphere acts like wax: when the hot material of the asthenosphere
rises, it swells and breaks creating new volcanoes. The highest volcanoes are at the
bottom of the oceans, where there are the Mid-Ocean ridges.
GLOSSARY
n. Wax = cera
v. To melt = become liquefied by heat = sciogliere
v. To pour = versare
v. To swell = gonfiarsi
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ACTIVITY 8
Materials:
- two beakers
- a bowl
- mashed potatoes
- flour
- red food dye
- polystyrene tray
- two square cardboards
- scissors
Procedure:
- Put three tablespoons of mashed potatoes in each beaker.
- Add some red food dye to one mixture and a tablespoon of flour to the other
one; mix.
- Cut a fissure in the middle of the polystyrene tray.
- Pour some mixture of mashed potatoes and flour on a sector of the tray and
some coloured mashed potatoes on the other sector.
- With the cardboard, push the mixtures one against the other. What can you
observe?
The mashed potatoes with flour fall into the fissure and the coloured mixture
slides over it and creates a “mountain chain”. In fact the mixture with the flour is
heavier than the other, and sinks into the coloured one, which is lighter.
The same happens in the ocean floor: new ocean floor is formed at the mid –ocean
ridge, it becomes cold and heavier and sinks into the mantle, creating the oceanic
trench.
GLOSSARY
n. Bowl = round container = scodella
a. + n. Mashed potatoes = purè
n. +n. (Food) dye = substance used to change the colour of food = colorante per
alimenti
n.+ n. Polystyrene tray = vassoio di polistirolo
n. Trench = fossa
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SCUOLA MEDIA STATALE “TOTI DAL MONTE”
31021 MOGLIANO VENETO (TV)
PROGETTO COMENIUS LINK
A.S. 2007/2008
Name:__________________________________
Class: ____ Date: ________________________
Theme: “Continental drift”
FINAL TEST
1) Match each definition with the correct term:
a. mantle
b. Pangaea
c. subduction
d. convection current
e. fossil
f. asthenosphere
g. mid-ocean ridge
h. crust
i. Panthalassa
j. continental drift
k. lithosphere
l. earthquake
1. trace of an ancient organism that has
been preserved in rock
2. hypothesis that the continents slowly
move across Earth’s surface
3. movement of a fluid, caused by
differences in temperature, that transfers
heat from one part of the fluid to another
4. layer of rock that forms Earth’s
surface
5. process by which oceanic crust sinks
into the mantle
6. undersea mountain chain where new
ocean floor is producted
7. a trembling of the Earth
8. a portion of the upper mantle in which
the rocks have a plastic behaviour
9. name of the single landmass that broke
apart 200 million years ago
10. the rigid outer shell of the Earth
which includes the crust and a portion of
the upper mantle
11. the ancient ocean that surrounded a
gigantic supercontinent
12. layer of Earth located between the
base of the crust and overlying the core
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2) Word search: find the most used words that you learnt (there are 12 words):
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3) Fill in the gaps. Choose the correct word in the Word Bank:
In 1915 ............................................. first proposed the theory of
.................................................. . He hypothesized that there was a gigantic
supercontinent 200 million years ago (...........................) surrounded by a gigantic
ocean (............................................). The fit of the continents and the distribution of
...................................... and rocks supported his theory. The continents are still
moving today.
Wegener’s model was not accepted by all geologists, because he could not
explain what kind of ............................... could be strong enough to move such large
masses of solid rock over such great ................................... .
Some years later, geologists hypothesized that in the ............................ of the
Earth there are very slow ...................................................... : the deepest material,
that is very hot, ........................... , becomes cool, flows laterally and then
.................... . The lithosphere seems to float over these convection currents.
In 1962 .......................................... proposed that new ocean floor is formed at
the top of ......................................................... . Convection cells in the mantle help
carry the ............................................. away from the ridge: the lithosphere arrives at
the edge of the continents where it is ................................ , that is it sinks into the
................................................ .
Word bank: Harry Hass, subducted, mid-ocean ridges, Panthalassa, Pangaea,
distances, forces, convection currents, Wegener, falls, rises, mantle, continental drift,
fossils, asthenosphere, lithosphere.
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