Download MS Unit 2 Part 2 Plate Tectonics

Opening Assignment
NO PHONES or DEMERITS!
1. What are the three things that we think
have contributed to the formation of our
oceans?
2. What is located at 0° latitude?
3. What is located at 0° longitude?
4. Which continent would you find at
A. 80° S, 20° E
B. 40° N, 80° E
Marianas Trench Video
questions – Copy and complete
1. What caused the formation of the
Marianas trench?
2. Where is it located?
3. What are some limitations scientists
faced when trying to explore the Marianas
Trench?
4. Is there life down there? How?
Marianas Trench – the Deepest
Place on Earth
• https://www.youtube.com/watch?v=iMEmP
SnjZDI
Marianas Trench Video questions
– Pull your copy out to review
your homework
1. What caused the formation of the
Marianas trench?
2. Where is it located?
3. What are some limitations scientists
faced when trying to explore the Marianas
Trench?
4. Is there life down there? How?
Our Dynamic Earth:
The Earth’s Crust in Motion
Learning Goals for Unit 2
Part 2 Plate Tectonics
• Students will be able to
– Explain how the Theory of Plate Tectonics
was derived on evidence
– Describe how the plates move and
continuously change the shape of the Earth
and it’s oceans
The World as We Know It …
But, have the continents always been in the
places that they are now?
Theory of Continental Drift
Continental Drift Theory
• Proposed by Alfred Wegener in 1912
• Super-continent called
“Pangaea”
• The continents
gradually drifted apart
to where they are today
Evidence to Support the Theory
1. “Puzzle Pieces”
• Continents look like
they could be part of
a giant jigsaw puzzle
2. Distribution of Fossils
• Plant and animal
fossils found on the
coastlines of different
continents
3. Sequence of Rocks
• Same rock patterns
found in South
America, India,
Africa, Antarctica
and Australia
4. Ancient Climates
• Tropical plant remains
(coal deposits) found
in Antarctica
• Glaciation in Africa,
South America, India,
and Australia during
the same time
Problems With The Theory
• No mechanism for movement of
continents
• Theory was not accepted by scientists
Theory of Plate Tectonics
Plate Tectonics
Plate Boundaries
Causes of Plate Tectonics
Structure of The Earth
• The Earth is made
up of 3 main layers:
Mantle
Outer core
Inner core
– Core
– Mantle
– Crust
Crust
The Earth’s Crust
• This is where we live!
• The Earth’s crust is
made up of:
Continental Crust
Oceanic Crust
- thick (20-30 mi)
- thin (3-4 mi)
- dense (sinks under
continental crust)
- young
- buoyant (less dense
than oceanic crust)
- mostly old
Plate Tectonics
What is Plate Tectonics
• The Earth’s crust is divided into 12 major plates
which are moved in various directions.
• This plate motion causes them to collide, pull
apart, or scrape against each other.
• Each type of interaction causes a characteristic
set of Earth structures or “tectonic” features.
• The word, tectonic, refers to the deformation of
the crust as a consequence of plate interaction.
World Plates
What are tectonic plates made of ?
• Plates are made up of rigid lithosphere
• The lithosphere is made up of the crust
and part of the upper mantle.
What lies beneath the tectonic
plates ?
• The plastic (able to be molded) layer
below the lithosphere = asthenosphere
• The plates of the lithosphere float on the
asthenosphere
Plate Movement
• “Plates” of lithosphere are moved around by
the underlying hot mantle convection cells.
Plate Movement
• Plate tectonics intro movie
Let’s Review
Write the question and the answer in your notebook
• What is the evidence to support the theory of
Continental Drift?
• What was the problem with the theory?
• What are the two types of plates?
• What is the connection between the
asthenosphere and the lithosphere?
• How do tectonic plates move?
Plate Boundaries
What happens at plate boundaries?
3 types of boundaries:
1. Divergent
2. Convergent
3. Transform
It all started in the ocean…
• Much of what we know
about plate tectonics was
learned by marine
geologists studying the
deep ocean floor after
WW2.
• They noticed an undersea
mountain range in the
middle of the ocean
(named it the mid-ocean
ridge).
• They began to study the ridge and learned
that the rocks along the ridge are VERY
young (geologically speaking). As you
move out from the ridge, the rocks get
older.
• Also, there is very little sediment along the
ridge but as you get further away, the
sediment gets deeper and deeper. Why?
What formed the mid-ocean ridge?
• The hot semi-solid molten mantle pushes
up between the plates. What happens?
Sea-Floor Spreading. The plates push
apart and new sea floor is formed when
the hot semi-solid molten mantle cools.
1. Divergent Boundaries
Two Types:
A. Oceanic
B. Continental
A. Divergent Oceanic Boundary
Click to play animation
Effects include: a submarine mountain range such as the Mid-Atlantic Ridge,
shallow earthquake activity, creation of new seafloor and a widening ocean
basin.
Age of Oceanic Crust
Effects of Oceanic Divergent Boundary:
Sea floor spreading
- Creates new sea floor
Iceland: Where the Mid-Atlantic Ridge
emerges on land.
• Iceland has a divergent
plate boundary running
through its middle
B. Divergent Continental
Boundary
Effects of divergent continental boundary include: creation
of rift valley (may become a new sea or gulf), earthquakes
Great African Rift Valley
2. Convergent Boundaries
• Boundaries between two plates that are
colliding
• Three types of convergent plate boundaries
A. Oceanic-Continental
B. Oceanic-Oceanic
C. Continental-Continental
A. Oceanic-Continental Convergent
Boundary
• Subduction Zone
• Oceanic-Continental Cont’d:
– Oceanic plate slides (subducts) under the
continental plate (because the continental
plate is lighter)
– Begins to melt
– Melting produces magma chambers which
slowly rise through the continental crust
– This movement of magma may cause
earthquakes
– If the magma chamber rises to the surface it
will break through as a volcanic eruption.
Oceanic-Continental Convergent Plate Movement:
Click to play animation
Effects of oceanic-continental boundary include:
Deep ocean trenches, earthquakes from rising
magma, volcanoes on land
Subduction
• Oceanic plate subducts underneath
continental plate
• The melting crust rises forming
volcanoes
• E.g. The Andes, Cascades of WA
B. Oceanic-Oceanic Convergent
Boundary
• When two oceanic plates collide, one (the older, more
dense one) subducts under the other..
• The subducting plate is forced downward to form a very
deep depression in the ocean floor called a trench.
• The worlds deepest parts of the ocean are found along
trenches. (Mariana Trench is 35,840 ft!)
Oceanic-Oceanic Convergent Plate
Movement:
Click to play animation
Effects include: earthquakes, an oceanic trench, a chain of volcanic
islands, and destruction of oceanic crust.
Aleutian Islands
C. Continental-Continental
Convergent Boundary
– Very powerful collision
– Both plates are light so neither subducts
– Cause broad folded mountain ranges (ex.
Himalayan Mountains where Indian and
Eurasian plates are colliding)
– Both plates may get thicker where the
collision occurs
Continental Convergent Plate
Movement:
Click to play animation
Effects include: intense folding and faulting, a broad folded mountain range,
shallow earthquake activity, compressing and thickening of the plates within
the collision zone.
Himalayas
3. Transform Boundaries
• Where plates slide past each other
• Earthquakes occur along faults
Above: View of the San Andreas
transform fault
San Andreas Fault, CA
Opening Assignment
• What formations happen at the following
boundaries?
• A. Convergent Continental to Continental
• B. Divergent Oceanic to Oceanic
• C. Convergent Oceanic to Continental
Plate Tectonics Edible Lab
• Today you will complete the Plate
Tectonics Edible Lab.
• You will work in groups of 2-3 to complete
1 work packet. You CANNOT eat your
tectonic plates until you have completed
the work packet or you will get a ZERO for
the assignment.
Study Guide
• Don’t forget to c0omplete the study guide
located under Unit 2 on my website.
Volcanoes and Plate Tectonics…
• What’s the connection?
Volcanoes are formed by:
• Subduction at a convergent boundary
(oceanic/oceanic OR oceanic/continental)
• Oceanic divergent boundaries
• Hotspots
Pacific Ring of Fire
Hotspot
volcanoes
What are Hotspot Volcanoes?
• Hot mantle plumes breaching the surface
in the middle of a tectonic plate
The Hawaiian island chain is an
examples of hotspot volcanoes.
Photo: Tom Pfeiffer / www.volcanodiscovery.com
Volcanic Island Chains
The tectonic plate moves over a fixed hotspot
forming a chain of volcanoes.
The volcanoes get younger from one end to the other.
Hawaiian Island Chain
• Some island chains are formed when the
oceanic plate moves over a “hot spot” in
the Earth’s mantle
• The Hawaiian Archipelago
Earthquakes and Plate Tectonics
What’s the connection?
Where do earthquakes form?
Figure showing the tectonic setting of earthquakes
• How do tsunamis relate to earthquakes?
Volcano-Earthquake Connection
• Correlation between plate boundaries and
volcanoes and earthquakes
Plate Tectonics Summary
• The Earth is made up of 3 main layers (core,
mantle, crust)
• On the surface of the Earth are tectonic plates
that slowly move around the globe
• Plates are made of rigid crust and upper mantle
(lithosphere) and move around on plastic
asthenosphere
• There are 2 types of plates
• There are 3 types of plate boundaries
• Volcanoes and Earthquakes are closely linked to
the margins of the tectonic plates
Plate Tectonics Review
Mountain Maker...Earth Shaker
Opening Assignment
Plot the following locations on your map and label
them with the corresponding letter.
•
•
•
•
•
Location E
Location F
Location G
Location H
Location I
27°N, 110°W
15°S, 15°W
25°N, 80°E
45°S, 135°E
68°N, 20°W
Opening Assignment 2
1. What is the name of the super continent
that occurred 225 million years ago?
2. Which layer of the earth is semi-solid and
beneath the crust?
3. Compare and contrast the two types of
plates.
Opening Assignment 3
1. Sea floor spreading occurs at what type
of boundary?
2. At which boundary would you expect to
find a deep ocean trench?
3. Which type of plate is thin and heavy?
4. Describe the layers of the earth.
Opening Assignment
• Write a paragraph explaining the process
of plate tectonics.
Opening Assignment
Write each question and answer in your notebook.
• What are the three types of boundaries?
• What direction do plates go for each?
• Which boundaries have a subduction zone…what occurs
at a subduction zone?
• What causes plates to move? Be Specific!
• Which two types of tectonic activity are associated with
the movement of Earth’s plates?