what features of the earth do you see in this picture??
TRANSCRIPT
What features of the earth do you see in this
picture??
What is the burning rock called? Where does it come
from?
What causes such an eruption of lava from the earth??
From this image showing lava flowing from dry land into the ocean, what do you think
this chapter might be about??
Plate TectonicsChapter 5
Section 1 Drifting Continents
Objectives:› Describe how the continents moved
over the past 250 million years› Explain the evidence supporting
continental drift› Make a model of the supercontinent
Pangaea
Skills Warm-up
A puzzling World› Look at the map on the next slide and
study the shapes of the continents closely.
› What do you notice about the shapes of the continents on the opposite sides of the Atlantic Ocean?
Drifting Continents
Hundreds of years ago, the 1st _________ ________ were made
People noticed that some of the continents could ___________ like ________ _________
But if the continents were once joined, how could they have moved??
Theory of Continental Drift
During the 1800’s, scientists studying ______ ____ ______ found evidence that seemed to support the idea of ________ ____________
What evidence do you think this was?
Alfred Wegener (1880-1930)
German _____________ Gathered evidence
and proposed the ___ ______ ___ _________ __________
Claimed that all landmasses were once joined as a supercontinent – _____________
Theory not accepted until the 1950’s
Activity
Pangaea Worksheet Page 20 of Integrated Resource Book
The Breakup of Pangaea
Scientists have collected large amounts of _______ on how the continents _______
They have pieced together a ________ of the continents
The Breakup of Pangaea
______ ________ ____ ___________________
All of the continents were part of one ___________________ called Pangaea
The Breakup of Pangaea
Step 1 ______ ________years
ago (Mesozoic Era) Pangaea began to
_______ ___________ across its __________
2 major continents formed› __________________
(south)› __________________
(north)
The Breakup of Pangaea
Step 2 _____ _________
years ago _________________
began to break up into _________ pieces that would become› _______________› _______________› _______________› _______________› _______________
The Breakup of Pangaea
Step 3 ____ _________ years ago _________ breaks apart
forming landmasses that would become› ________________› ________________› ________________
_________, which has been drifting north for 100 million years, collides with ________
The Breakup of Pangaea
Step 4
Continents as they _________ _______
Do you think the continents will keep moving around??
Activity
Watch movie “Plate Tectonics – Our Restless Planet” from Discovery Education
Write down 10 things you learned from movie and hand in at end of class
Activity
Continental Drift Lab Page 29 of Laboratory Manual
Evidence for Continental Drift
Scientists have collected a lot of evidence supporting 2 related conclusions› 1.____________________
_______________________________________________________________
› 2. ____________________________________________________________________________________
Fossil Evidence
A _________ kind of organism or species appears on earth only in ______ _______and then _________ _____
Animals that swim and plants with windblown seeds can spread _________ ___ _________
But, _______ _________ can only spread out across land
Fossil Evidence ___________________
found fossils of an ancient fernlike plant called _____________ in› _________________› _________________› _________________› _________________› _________________
What can they infer from this??
Fossil Evidence
That all of these continents were ________________ at one time!!
Fossil Evidence
Fossils of several other species have a similar pattern
None of these organisms could have __________ ___ _____________
How could they end up on different continents??
Fossil Evidence Fossils of _____________,
a Triassic land reptile, were found in Africa, Antarctica, and India
Fossils of _____________, a freshwater reptile, were found in Africa and South America
Fossils of _____________, a Triassic land reptile, were found in South America and Africa
Fossil Evidence
Fossil evidence also shows that the continents have ___________ over the earth’s surface
Fossils found in _____________ show it once was home to vast ______ _________ and _________ full of plant and animal life
How could this be??
Rock Evidence There are many
___________ between the rocks and landforms of _______ and ______ _________
If the 2 continents are fitted together, their __________ _______ ______ ____
Also, the mountain’s rocks are similar in _____ _____ _______
Were the 2 mountain ranges once one??
Activity
Watch movie “Fossils – Windows into the Past” from Discovery education”
Write down 10 fossil facts from movie and hand in at the end of class.
Skills Warm-up
Is it True??› Recall a time when someone told
you that something you believed to be true, really wasn’t.
› How did you react?› Was your reaction similar to the way
scientists reacted to Wegener’s ideas?
Evidence from Ancient Glaciers
______ are huge masses of ______ that move ________ over land
During the ice ages, glaciers spread _________ _____ _____ _________
Glaciers always move __________ _____________
Evidence from Ancient Glaciers Rocks that show
evidence of glaciers at the end of the _________ ______ were found in› _________________› _________________› _________________› _________________
How could this be if it is usually hot in these places??
Evidence from Ancient Glaciers
Rocks can also show the ________________ in which glaciers ________________
Ice age glaciers seemed to travel __________ from present day ________
This doesn’t make sense!!
Evidence from Ancient Glaciers
Can only be explained if the following continents were once part of the _______ _________› _________________› _________________› _________________› _________________› _________________
Activity - Answer the following questions on a sheet of paper and turn in by the end of class
1. Which present day continents were once part of Gondwanaland?
2. List 2 types of evidence that support the idea of continental drift.
3. What will happen to the size of the Atlantic Ocean in the next 50 million years?
4. If you found evidence of glaciers in areas with warm climates, what would you conclude?
5. How does evidence of glacier movement support the idea of a single landmass?
Section 2 Theory of PlateTectonics
Objectives:› Describe the process of sea-floor
spreading› Identify different types of plate boundaries› Explain what happens when plates come
together› Infer from observation of a large surface
feature what kind of plate boundary produced it
Skills Warm-up
Moving Plates› The word plate means “a smooth,
flat, thin piece of material”› The word tectonic means “having a
strong and widespread impact”› Does this give you enough
information to get a good idea of what plate tectonics is all about?
Ocean-Floor Discoveries
1950’s – Scientists finally got the tool they needed to study the ocean floor
_______ __________ – could bounce ________ waves off the ocean bottom › if a sound wave bounced
back _________, the ocean floor was ___________
› if a sound wave took longer to bounce back, the ocean floor was __________
This allowed them to make a map of the ______________ of the ocean floor
Ocean-Floor Discoveries Scientists discovered
long, underwater ____________________
The ranges formed one long __________ snaking through all of the oceans (baseball seams)
This ________________ had a deep valley running the length of its crest
Ocean-Floor Discoveries
Scientists found rocks from the ocean bottom were _________ than the rocks in the ____________
Also the rocks _________ to the mid-ocean ridge were the ______________
Why do you think this is??
Sea-Floor Spreading 1960 – American
geologist ______________ proposed the __________ ________________________
› 1. Mid-ocean ridge is a huge ___________ in the earth’s crust where the hot _________ pushes up
› 2. The pieces of crust on either side of the crack are slowly moving _______ from each other
› 3. As they move, _______ _______ from the mantle wells up between them, forming ______ _________ ___________
Sea-Floor Spreading
New ocean crust is constantly being _______ during sea-floor spreading.
So why doesn’t the earth keep growing bigger??
Because at the same time, ________ ocean crust is being _________ ____ in deep _______ ___________!
The ______ _________ of oceanic crust stays the _______ and it is totally remade every ______ __________years or so.
Sea-Floor Spreading
Other scientists sampled rocks on ______ _______of the mid-ocean ridge
They found a pattern of _________ ________ _________ that was _________ on each side
Sea-Floor Spreading The stripes were
formed when the earth’s magnetic field caused ___________ to line up in the rocks
The stripes were different because earth’s magnetic field ___________ itself many times in the past
Shows that new ocean crust is added to ______ ________ of the mid-ocean ridge at the _________ _________
Activity
Watch movie “The Endless Voyage – Making the Pieces Fit” from Discovery Education
Write down 10 new facts that you learned and hand in at end of class
Lab Activity
Magnetic Patterns on the Ocean Floor
Page 98 in Textbook
Plate Tectonics Earth’s lithosphere
is divided into pieces called __________
The plates are _______ ___________, each at a different rate and direction
A lithospheric plate moves as a _______, floating on top of the ______________ (like a flat rock on wet cement)
Structure of Earth’s Plates Each lithospheric
plate is made up of both ______ _______________
________ ________ is dense and made up of ______ _____ ___________
_________ _______ is less dense and made up of _______ _____ ___________
Continental Plates
6 of the earth’s 7 major plates are ______________ plates
They carry mostly continental crust material
They consist of _____ continent and a large section of __________ ________
Oceanic Plates
One major plate and several smaller plates are oceanic plates
They are made up entirely of ___________ __________
Plate Boundaries
If plates are moving, what kinds of interactions are possible??
Demonstration with 2 students
Divergent Boundaries
Plates moving ________ from each other
Places where ________ _______ __ ____ _______
______ _____ ______are divergent boundaries
Can also occur in continents and signal the beginning of the continent’s ___________
Convergent Boundaries
Two plates _______ ________ ___ ________
Usually one plate moves _________ another and crust material is _________
Produce many different kinds of features on earth’s surface
Transform Boundaries
Two plates ______ ____ ________ ___________ beside each other
Crust material is ______ created or destroyed
The break or crack along which movement occurs is called a _____________ ____________
Activity
Watch first part of movie “Endless Voyage – World in Motion” from Discovery Education
Define the following and hand in at end of class:
Divergent BoundaryConvergent BoundaryTransform Boundary
Convergent Boundaries
__________ of 2 plates release huge amounts of _________
Energy causes important _________ __________ – volcanic activity or mountain building
What happens depends on the ______ ___ _______that meet or converge
Oceanic Plate –Oceanic Plate
The more dense plate is pushed down under the other – ______________
Lower plate goes into _____________, melts, and is absorbed into ___________
Causes ______ ________to rise up through other plate› Volcanoes form on ocean
bottom and build a chain or _______ ___ ____________
› It also creates a ________ _________ ______ – deepest parts of the ocean
Oceanic Plate – Continental Plate
____________ plate is always _________ so it will be pushed down under the ____________
Oceanic plate melts into ________________, causing molten rock to rise up through ______________ plate
___________ __________ forms, usually containing ___________
Continental Plate – Continental Plate
Both plates are the same __________ and _____________
Neither can move ___________ the other
They __________ and _________ each other, forming _____ ________
Plates become joined as a _______ _________
Plate Geography
Certain instruments measure the slow movements of earth’s plates, so the _______ and ______________ of most have been determined – can _______ future movement
The movement and location of plates explains many of earth’s features:› _______________________› _______________________› _______________________› _______________________› _______________________› _______________________
Well-Known Features of Earth
___________________
One of the few transform boundaries on land
Its movement causes severe _______________ (California)
Well-Known Features of Earth
________ ___________
Nazca plate ____________ under the South American plate caused this mountain range
Well-Known Features of Earth
______ _____ _____
New ____________ boundary beginning to split Africa in two
Well-Known Features of Earth
_________________ __________
mountains on earth Resulted from
____________ of two continental plates
Well-Known Features of Earth
_________________ Ocean trench
more than _______ _________________
Created by _____________ of Pacific plate under the Philippine plate
Measuring Plate Movement
_____ ______ ________ _____________(VLBI) Uses ________ signals from distant _______
(stars) to measure plate movement Two stations far apart on earth receive
signals from the same quasar Get a precise measurement of _________
between the 2 stations Make same measurement at a later date
– find out how fast the earth’s plates are ______________
Hawaii and Japan are moving closer to each other at a rate of __________________________
The North American and Eurasian plates are moving apart at a rate of ______________________
Activity - Answer the following questions on a sheet of paper and turn in by the end of class
1. What happens during sea-floor spreading? 2. Describe 3 types of plate boundaries, and
give an example of each. 3. Explain how mid-ocean ridges and
subduction zones are similar. How are they different?
4. Japan is made up of a long chain of islands formed from volcanoes. What kind of plate boundary do you think is nearby?
5. What happens at a continental-continental plate boundary?
Section 3 Physics of PlateMovement
Objectives:› Describe two models of how convection
occurs in the earth’s mantle.› Explain how a tectonic plate may move as
part of a convection cell.› Evaluate models explaining plate
movement by convection.› Compare and contrast two models for how
convection results in the movement of plates
Skills Warm-up
Convey the Concept› Describe how a conveyor belt works.› Make a list of where conveyor belts
are used.› What happens to objects on a
conveyor belt?
What Moves the Plates??
Scientists know:› ___________________
___________________› ___________________
___________________› ___________________
___________________ Still don’t know for
sure what the driving force of plate movement is!
Convection in the Mantle
Driving force for plate movement has something to do with ____________________________________
_____________ cells occur in the mantle, which are circular units of movement
But how exactly does convection occur??
Two Models for Convection
How Does Convection Move the Plates?
First Model - Passive Plates are _______________
_________ with the movement of convection
Plates are like ___________ on a giant conveyor belt
________ _____________ form where convection pushes material up
_______ ______________ form where convection goes back down into the mantle
How Does Convection Move the Plates?
Second Model - Active Plates themselves have
an _______ ______ in convection
A plate is ________ and ______ _______ than the asthenosphere
It will sink into a _________ ________and pull the rest of the plate down
This helps _________ the circular movement of convection
Activity - Answer the following questions on a sheet of paper and turn in by the end of class
1. What are two models for convection in the mantle?
2. If convection cells in the mantle are like conveyor belts, what are plates like?
3. Which model do you think best explains how convection moves the plates? Explain the reason for your choice.
4. What are the similarities and differences between the two major models explaining how convection causes plate movement?