Transcript Restless Continents for Websitex

Today’s Goal:
What does Pangaea teach us about the lithosphere
and plate tectonics?
Warm-up: Read the “Using Evidence to Reconstruct
Pangaea” worksheet
Homework:
Earth’s Layers and Restless Continents Quiz Friday
Three Things Today:
1.
2.
3.
How do we know of Pangaea?
Reconstruct Pangaea using fossil, glacier and landform
evidence
DR 4.1, pp 100-102 in text, #19-24
Wrap-up:
What does Pangaea have to do with the lithosphere
and asthenosphere?
Key
Glossopteris Fossils
Mesosuarus Fossils
Lystrosaurus Fossils
Glacier Scars
Mountain Ranges
Coal Deposits
X
Recreating Pangaea Directions
• You will receive a map of the continents of the world and a blank
evidence key. Keep one copy of the “Using evidence to Recreate
Pangaea” worksheet.
• Create a key and create symbols to use for each piece of
evidence given. Colored pencils will help you further identify
each piece of evidence on your map.
• Carefully cut out all the continents and key.
• Piece together Pangaea on a piece of blue construction paper
using the evidence symbols mapped on each continent.
• Call me over to check.
• Glue the continents down in the shape of Pangaea as well as the
symbol key.
• Title the paper, “Pangaea” and place in your class drawer.
• Go back to your seats and complete DR 4.1, 19-24, pp 100-102
Today’s Goal:
Warm-up:
How do we know about Pangaea’s existence?
Get your Pangaea Map; Complete DR 4.1, pp 100-102,
#18-24
Homework:
Complete Pangaea questions for tomorrow,
Quiz Friday
Three Things Today:
1.
2.
3.
Landforms Presentations
Pangaea PowerPoint
Pangaea Questions
Wrap-up:
Wegener believed the continents drifted. Why was
he right? Why was he wrong?
Building Pangaea Gizmo
Glossopteris-Fern plant found in India, Australia,
Antarctica, South America, Madagascar, & Africa.
Lystrosaurus – Reptile found in Africa, India,
Antarctica, and Madagascar
Mesosaurus- Reptile that swam in freshwater lakes
& rivers found in South America and Africa.
Subtropical Deposits – Coal deposits found in South
America, Eurasia, and North America
Glacial Scarring- Glacier evidence in South America,
Africa, India, Antarctica, Madagascar & Australia.
Mountain Ranges –Appalachian Mountains found
in North America, Eurasia, Africa, and Greenland.
Shape of continents
Mesosaurus
Both Mesosaurus and Glossopteris were organisms that would
not have been able to travel to the different continents at the
distances that the continents are at today.
But the fossils on various
continents make sense when
you put them back together.
Wegener’s
matching of
mountain ranges
on different
continents
Some of
the oldest
mountains
on Earth
When they
formed,
they were
about 5
times as
high as
they are
today!
How can we account
for the evidence of
ancient glaciers in all
of these areas?
Meanwhile, coal deposits
are found in areas that are
no longer tropical
Pangaea
(all Earth)
Tethys
Sea
TECTONIC PLATES
1. What are tectonic plates?
•
Pieces of lithosphere that move around on top of the asthenosphere.
2. Why are tectonic plates like pieces of a jigsaw puzzle?
•
Each tectonic plate fits together with the tectonic plates that surround it. The lithosphere is
like a jigsaw puzzle, and the tectonic plates are like the pieces of a jigsaw puzzle.
3. What are the two kinds of crust that a tectonic plate may contain?
• Oceanic crust AND continental crust
4. List three ways in which tectonic plates floating on the asthenosphere are similar to ice cubes filling a
punch bowl.
• Tectonic plates “float” on the asthenosphere, cover the surface, and touch one another as they
move around.
5. What do scientists use to study the earth’s interior?
•
Seismic Waves
6. What are seismic waves?
•
Vibrations caused by earthquakes.
7. Will a seismic wave traveling through a solid go faster or slower than a seismic wave traveling through
liquid? WHY OR WHY NOT?
• A seismic wave traveling through a solid will go faster than through a liquid because the solid is
more dense and the particles are not moving as fast.
 Alfred Wegener
• 1915
• Proposed idea of Continental Drift
 Continental drift hypothesis
• Supercontinent called Pangaea began
breaking apart about 200 million years
ago
• Continents "drifted" to present
positions
approximately
200 million
years ago
Pangaea Analysis Questions
1. Why was the discovery of mesosaurus fossil in modern-day South America and Africa
significant to Alfred Wegner?
2. How did the position of the mountain ranges on the continents help you piece together
the representation of Pangaea?
3. Explain how subtropical plants were once able to grow in regions of present-day North
America and Eurasia in which they cannot grow today?
4. Which continent drifted south upon the breakup of Pangaea? What evidence from
Wegner’s data leads you to this conclusion?
5. Which continent moved the greatest distance from its position within Pangaea to its
present-day location? Give an example from Wegener’s data to describe how climate
changed on this continent as a result of the new location?
6. In the space below make a bulleted list of ALL the pieces of evidence Alfred Wegener used
to support his idea of Continental Drift.
Your Turn
• Pangaea Activity Analysis Questions
• You need to complete your own questions
• If you finish early, please work on DR 4.2 #1-7
So was
Wegener’s
theory totally
right?
Wegener’s
Pangaea
Almost…
200
million
years ago
His layout of Pangaea was a little
off, but more importantly, he
thought that it was just the
continents themselves that
moved. He didn’t realize that the
continents are just part of much
bigger plates.
Today’s Goal:
Warm-up:
What is the mechanism for Continental Drift?
DR 4.2, pp 104-107, #1-8
Homework:
Pangaea questions—extra day if needed for
questions, quiz Friday! Restless Continents
Three Things Today:
1.
2.
3.
Landform Presentations
Seafloor Spreading Activity Part 1
Seafloor Spreading PP
Wrap-up: Label your Seafloor Diagrams
Pangaea Analysis Questions
1. Why was the discovery of mesosaurus fossil in modern-day South America and Africa
significant to Alfred Wegner?
2. How did the position of the mountain ranges on the continents help you piece together
the representation of Pangaea?
3. Explain how subtropical plants were once able to grow in regions of present-day North
America and Eurasia in which they cannot grow today?
4. Which continent drifted south upon the breakup of Pangaea? What evidence from
Wegner’s data leads you to this conclusion?
5. Which continent moved the greatest distance from its position within Pangaea to its
present-day location? Give an example from Wegener’s data to describe how climate
changed on this continent as a result of the new location?
6. In the space below make a bulleted list of ALL the pieces of evidence Alfred Wegener used
to support his idea of Continental Drift.
Plate Tectonic Activity
• Take 2 pieces of lined paper and tape short ends ( 8 inch
sides) to one another
• Place taped ends through the middle of where your desks
meet until you have 2.54 cm (1 inch) remaining on your
desk held by your fingers
• Take a pencil and draw a straight line across your paper
following the edge of the desk. Do this on both paper
sides. Label each side 1st.
• Pull out the paper from the desk slowly counting to 5.
Stop and draw a line across your paper following the edge
of the desk. Do this on both paper sides. Label each side
further in succession(2nd, 3rd, 4th). Repeat until complete.
Sooo..Who is Alfred Wegener?
 Alfred Wegener
• 1915
• Proposed idea of Continental Drift
 Continental drift hypothesis
• Supercontinent called Pangaea began
breaking apart about 200 million years
ago
• Continents "drifted" to present
positions
But remember,
Pangaea wasn’t
the very
beginning.
Present
day
Earth’s
formation
(4.6 BYA)
What scale are we working with?
4 Billion Years Ago
3 BYA
2 BYA
Pangaea
1 BYA
0 BYA
•
•
People couldn’t observe the plates moving
The main objection to Wegener's proposal was
its inability to provide a correct mechanism
• In other words, he couldn’t
explain HOW and WHY the
continents drift.
• Wegener didn’t know the
driving force.
• He claimed it was the same
forces that influence tides
(gravity).
Please open to p. 106 in your textbook:
A-HA!
I knew it!
What feature can be found in the
middle of the Atlantic Ocean, which
showed that Wegener was right after
all? What does this feature look like?
Describe what’s happening there.
• Creation of new _____________
lithosphere (new oceanic crust)
asthenosphere
 Hot magma pushes up from the _______________
Where is this
currently
happening?
Mid-ocean
ridge
Seafloor Spreading Activity
• Label where you think the oldest rocks are.
• Label where you think the youngest rocks are.
• What should you label the middle, taped section?
Today’s Goal:
How is the idea of Magnetic Reversal the final proof
of Continental Drift?
Warm-up:
Journal Entry—Write question and then answer—Explain
why the Appalachian Mountains are so much older than the
Himalayan Mountains
Homework: Earth’s Layers and Continental Drift Quiz now
Monday
Bring headphones tomorrow and Monday
Three Things Today:
1.
2.
3.
Landform Presentations
Magnetic Reversal PP
Seafloor Spreading Activity Part 2
Wrap-up: Review DR 4.2
1. Why was the discovery of Mesosaurus fossil in
modern-day South America and Africa significant
to Alfred Wegner?
The fossils found in South America and Africa were
separated by vast expanses of ocean, yet appeared to
be the same species. This indicated to Wegener that
the organisms evolved together on one
supercontinent before the landmass broke apart and
drifted to its present day location.
2. How did the position of the mountain ranges
on the continents help you piece together the
representation of Pangaea?
The mountain ranges in North America, Greenland,
and Eurasia connected to form a continuous belt
when these continents were brought together and the
mountain range symbols were aligned. The mountain
ranges formed a continuous chain within Pangaea but
became separated when the continents split apart.
3. Explain how subtropical plants were once able
to grow in regions of present-day North America
and Eurasia in which they cannot grow today?
North America and Eurasia were once positioned to the
south of their present locations much nearer the equator.
As such, they had a warmer climate that supported the
growth of tropical plants. When Pangaea broke apart,
these continents drifted further north where their
climates became more temperate. As a result of this
positional shift, the subsequent climate change no longer
supports the growth of subtropical plants.
4. Which continent drifted south upon the breakup of
Pangaea? What evidence from Wegner’s data leads you to
this conclusion?
Antarctica drifted south towards the southern pole
while the continents drifted north. Fossils of
Glossopteris plants and Lystrosaurus reptiles were
found on Antarctica. However, the present-day
climate of this continent is too cold to support such
plant and animal life. Antarctica’s move south to a
more frigid climate upon the breakup of Pangaea
explains this discrepancy.
5. Which continent moved the greatest distance from its
position within Pangaea to its present-day location? Give an
example from Wegener’s data to describe how climate
changed on this continent as a result of the new location?
India has moved to the farthest distance from
Pangaea to its current location against Eurasia. India
was originally located far to the south where the
formation of glaciers was possible. Its current climate
is too warm to support the formation of glaciers.
6. In the space below make a bulleted list of ALL the
1. of
Glossopteris-Fern
plant Alfred
found in India,
Australia, Antarctica,
Southto
America,
pieces
evidence
Wegener
used
support
his
Madagascar, & Africa.
ideafound
ofinContinental
Drift.
2. Lystrosaurus – Reptile
Africa, India, Antarctica,
and Madagascar
3.
4.
5.
6.
7.
Mesosaurus- Reptile that swam in freshwater lakes & rivers found in South America
and Africa
Subtropical Deposits – Coal deposits found in South America, Eurasia, and North
America
Glacial Scarring- Glacier evidence in South America, Africa, India, Antarctica,
Madagascar & Australia.
Mountain Ranges –Appalachian Mountains found in North America, Eurasia, Africa,
and Greenland.
Shape of the continents
Seafloor Spreading—Driving Force of
Plate Tectonics
O l
d e s
Y o u n g e s
t R o c k
i
c R
t R o c k
- O c e a n
t R o c k
d
Y o u n g e s
t R o c k
M i
d e s
O l
i
d g e
Mid-ocean
ridge
What is the final piece of evidence that
essentially proves seafloor spreading
really occurred and caused continental
drift?
• Magnetic Reversals  Magnetic poles of Earth have
changed throughout time (North and South switch)
• Basalt is mafic, which means it contains tiny grains
of ________
iron (WHICH IS MAGNETIC). When the
rock cools, the minerals align with the Earth’s
magnetic poles at the time of cooling.
• So… sea-floor spreading records magnetic reversals
Where did the reversal actually take place?
SN
SN
What layer creates Earth’s Magnetic Field?
•Outer Core
Albert Einstein called the generation of
Earth’s magnetic field one of the
GREATEST MYSTERIES in physics.
Scientists are still NOT SURE how the
field is generated, though it is clearly related
to the movement of molten iron in the
liquid outer core.
THE FIELD
SWITCHES BACK AND FORTH
Satellites have detected two
areas in the mantle that appear
to have reversed polarity.
Even more puzzling is WHY
between normal and reversed polarity
.
This data has led some to
speculate that a magnetic
reversal may be soon (in
geologic time).
Seafloor Spreading and Magnetization
1) Which stripes of
rock formed first?
2) What polarity would
you expect to find
there?
3) Which stripe of rock
is currently
forming?
4) What polarity would
you find there?

Reversed polarity

Normal polarity
Mid-ocean
ridge
Alternating
magnetic fields
Seafloor Spreading Activity
• Take your seafloor labeled diagram and 2 different colors
of crayons, colored pencils
• On both sides, where you labeled 1st,draw an arrow
pointing north -Assign this polarity one of your colors and
shade it in.
• Where you labeled 2nd, draw your arrow and label north
in the opposite direction—Assign this reversed polarity a
different color and shade it in
• Continue drawing arrows, labeling north and south in
alternating positions, and coloring each band alternating
colors for every section you have on your papers.
• Make sure the sections are labeled the same on each side
of your model
Seafloor Spreading—Driving Force of
Plate Tectonics
O l
d e s
Y o u n g e s
t R o c k
i
c R
t R o c k
- O c e a n
t R o c k
d
Y o u n g e s
t R o c k
O l
d e s
M i
Normal Polarity
i
d g e
Reversed Polarity
Chapter 4, Section 2: Restless Continents Pages
1. In the early 1900s Alfred Wegener wrote about his hypothesis of continental
drift. According to Wegener, how were the continents arranged 245 million
years ago?
One supercontinent called Pangaea
2. What did Wegener hypothesize happened to these continents?
They broke up and drifted to their current locations.
3.
How does fossil evidence support Wegener’s theory? Explain.
Yes, because fossils of the same plant and animal species are found on
continents that are on different sides of the Atlantic Ocean.
4. List three kinds of evidence found on both sides of the ocean that support
Wegener’s theory.
Fossils, rock evidence, and same ancient climatic conditions.
5. Wegener thought that all the present continents were once joined 245 million
years ago in a landmass he called Pangaea.
6. 180 million years ago Pangaea split into two huge land masses called Laurasia
AND Godwana.
6. When those two continents split 65 million years ago, what were formed?
The continents that we know today.
7. Why did so many scientists reject Wegener’s hypothesis? From the calculated strength of
the rocks, it did not seem possible for crust to move in this way. Additionally, there was no
way to explain what caused the crust to move.
8. In the process of sea-floor spreading, what happens when magma rises to the Earth’s
surface and solidifies?
It forms new oceanic lithosphere and pushes the older crust away from the mid-ocean ridge.
Match the correct definition with the correct term. Write the letter in the space provided
9. Process of forming new oceanic lithosphere as magma rises to the surface
c
10. Areas where sea-floor spreading takes places
b
11. Process that happens when Earth’s magnetic poles change place
d
12. Theory that explains how continents reached their current locations.
a
a. continental
drift
b. mid-ocean
ridges
c. sea-floor
spreading
d. magnetic
reversal