ONLINE ACTIVITY: PLATE TECTONICS Using the web links provided in the Science10 handout folder complete the following activities and answer the questions listed.

Use the web link provided in the Earth Science Folder www.pbs.org/wgbh/aso/tryit/tectonics Scroll down and click on the link to “Intro to Plate Tectonic Theory”. Read the material

provided and answer the following questions:

1. What is the theory of plate tectonics?

PLATE TECTONICS IS A THEORY THAT THE OUTER, RIGID, LAYER OF THE EARTH (THE LITHOSPHERE) IS DIVIDED INTO PLATES THAT MOVE

AROUND ACROSS THE EARTH’S SURFACE RELATIVE TO EACH OTHER.

a) Plate tectonics is the theory that EARTH’S OUTER LAYER IS MADE UP OF PLATES THAT HAVE MOVED throughout the Earth’s history.

b) 225 million years ago all of the major continents formed a SUPERCONTINENT

called PANGEA.

c) Are the continents still on the move today? YES.

d) There are two theories that attempt to describe the forces behind plate tectonic

movement. Briefly describe what they are:

i) CONVECTION WITHIN THE EARTH’S MANTLE PUSHES THE

PLATES.

ii) GRAVITY IS PULLING THE OLDER, COLDER & THUS HEAVIER

OCEAN FLOOR W/ MORE FORCE THAN THE NEWER, LIGHTER SEA FLOOR.

Explore the following video links:

1. Mantle Cells and Continental Drift http://www.youtube.com/watch?v=p0dWF_3PYh4

2. Plate Tectonics http://www.youtube.com/watch?v=ryrXAGY1dmE&feature=related

3. Plate Boundary types http://www.youtube.com/watch?v=1-HwPR_4mP4&feature=related

4. Sea Floor Spreading http://www.youtube.com/watch?v=GyMLlLxbfa4&feature=watch-vrec

The three types of plate boundaries are:

1. DIVEGENT, 2. CONVERGENT, and 3. TRANSFORM,

Now open the Phet Simulation “Plate Tectonics”. You can also find this link/simulation in the

Earth Science folder on the computer.

INVESTIGATING THE CRUST

Check the “Show Labels” box. Select the density meter and the thermometer and move them to the

to the middle crust just below the bottom of the ocean as shown:

1. Change the temperature slider and observe the affect on the middle crust. Observe carefully!

Record your observations: AS THE TEMPERATURE INCREASES, TEMPERATURE IN MIDDLE CRUST ALSO INCREASES.

2. Reset the temperature slider and change the composition slider instead and observe the

affect on the middle crust. Observe carefully! Record your observations: OCEAN CRUST HAS MORE IRON & CONTENTAL CRUST HAS MORE SILICA.

3. Reset the composition slider and change the thickness slider instead and observe the affect

on the middle crust. Observe carefully! Record your observations AS THE THICKNESS

INCREASES, DENSITY & TEMPERATURE DECREASE.

4. Turn on the temperature “View” selector. Move the density meter and thermometer to the

continental crust and then to the oceanic crust. Which has a higher density? What might be

the cause of this difference in density? CONTINENTAL CRUST HAS A LOWER DENSITY THAN THE OCEANIC CRUST. OCEANIC CRUST IS SMALLER &

HAS MORE IRON THAN CONTINENTAL CRUST.

5. Select the ruler and use it to measure the thickness of the oceanic and continental crusts.

Record:

Oceanic Crust = ~ 5 km, Continental Crust = ~ 50 km

INVESTIGATING PLATE MOTION - DIVERGING BOUNDARIES

DIVERGENING OCEANIC PLATE BOUNDARIES

Select two pieces of “Young Oceanic Crust” and drag them to the left and right side of the screen.

Activate Automatic Mode. Under the “View Window” select Both, Show Labels and Show Sea

Water. Select the “Divergent” Mode and move the “Time Elapsed slider” to a position just to the

right of slow. Press play and observe.

1. What do oceanic plates do at a divergent boundary? MOVE AWAY FROM EACH

OTHER. 2. Observe the zone where the plates are spreading apart. What is rising up at this location?

What would this rising material create? SHALLOW VALLEYS OR RIFTS. 3. What type of landform is created at the point of separation of the two plates? Observe

closely. Note a high point is called a ridge and a low point is a valley or rift. RIFT.

DIVERGING OCEANIC PLATES

Sketch the diagram shown in the simulation and label it:

Add labels to the following diagram:

DIVERGING CONTINENTAL PLATE BOUNDARIES

Select the RESET ALL button. Select two pieces of “Continental Crust” and drag them to the left

and right side of the screen. Activate Automatic Mode. Under the “View Window” select Both,

Show Labels only. Select the “Divergent” Mode and move the “Time Elapsed slider” to a position

just to the right of slow. Press play and observe.

1. What do continental plates do at a divergent boundary? MOVE AWAY FROM EACH OTHER.

2. Observe the zone where the plates are spreading apart. What is rising up at this location?

What would this rising material create? MAGMA BECOMES LAVA WHEN IT

REACHES THE EARTH’S SURFACE.

3. What do you notice about the thickness of the “new” land being created as compared to the

older continental plate? IT IS THINNER.

4. What type of landform is created in the space between the two older pieces of continental

plate? Observe closely. Note a high point is called a ridge and a low point is a rift or valley.

RIFT VALLEY.

DIVERGING CONTINTENTAL PLATES

Sketch the diagram shown in the simulation and label it:

SUMMARY DIVERGING BOUNDARIES: At a divergent plate boundary the plates are moving AWAY FROM EACH OTHER. As this

occurs MAGMA rises up in the space created between the DIVERGING plates. This MAGMA

then solidifies to create new crust. The new crust is thin and as a result is PUSHED upwards by

the HOT magma below it. This creates a high point called a RIDGE. In the center of this ridge is a

shallower valley called a RIFT. These ridges and rifts, are found mostly under the worlds oceans

and cover the earth like the seams on a baseball. VOLCANOES and earthquakes are found along

divergent boundaries. Iceland is a VOLCANIC island that is split down the middle by a rift valley.

Iceland is literally being ripped apart by the diverging movement of the North American and

Eurasian plates. The speed at which the plates move is very slow, measured in cm/year, and is

comparable to the speed at which your finger nails grow.

INVESTIGATING PLATE MOTION - CONVERGING BOUNDARIES

CONVERGENING CONTINENTAL/CONTINENTAL PLATE BOUNDARIES

Select two pieces of “Continental Crust” and drag them to the left and right side of the screen.

Activate Automatic Mode. Under the “View Window” select Both, and Show Labels. Select the

“Convergent” Mode and move the “Time Elapsed slider” to a position just to the right of slow.

Press play and observe.

1. What do the plates do at a Continental/Continental convergent boundary? PLATES MOVE

TOWARDS EACH OTHER. 2. What is being created where the two plates come together? MOUNTAINS.

3. Using the density meter check the density of both plates. How do the densities compare?

DENSITY OF BOTH CONTINENTAL PLATES IS EQUAL. 4. How long does it take for these mountains to be produced at a collision boundary. 35

MILLION YEARS.

CONVERGING CONTINTENTAL PLATES

Sketch the diagram shown in the simulation and label it:

CONVERGING CONTINENTAL/OCEANIC PLATE BOUNDARIES

Select the RESET ALL button. Select pieces of “Continental Crust” and “Old Oceanic Crust” and

drag them into place. Activate Automatic Mode. Under the “View Window” select Both, Show

Labels and Sea Water. Select the “Convergent” Mode and move the “Time Elapsed slider” to a

position just to the right of slow. Press play and observe.

1. What happens to the Oceanic plate as the plates converge? ONE PLATE IS PUSHED

BENEATH THE OTHER. 2. Using the density meter check the density of both plates. How do the densities compare?

DENSITY OF OCEANIC PLATE > DENSITY OF CONTINENTAL PLATE. 3. The process of one plate moving below another is called SUBDUCTION. Why is the

Oceanic plate subducting under the Continental plate? THE OCEANIC PLATE IS

MORE DENSE AND SUBDUCTS UNDER THE LESS DENSE, MORE BUOYANT CONTINENTAL PLATE.

4. What does the subduction process produce on the Continental Plate? VOLCANOES.

5. How are these VOLCANOES being formed? THE OCEANIC PLATE REMELTS

AS IT MOVES FURHTER UNDER THE CONTINENTAL PLATE. THIS

MAGMA THEN RISES UP AND ENTERS THE CRACKS OF THE OVERRIDING PLATE.

6. Where are these VOLCANOES located relative to the convergent boundary? Estimate a

distance using the ruler tool as a scale. 80 – 100 km 7. Deep parts of the Ocean are located at a place called a TRENCH. Locate the trench

being created by the convergence of these to plates. Where is the trench found?

WHERE THE PLATE IS PUSHED BENEATH THE OTHER.

CONVERGING CONTINENTAL/OCEANIC PLATES

Sketch the diagram shown in the simulation and label it:

CONVERGING OCEANIC/OCEANIC PLATE BOUNDARIES

Select the RESET ALL button. Select pieces of “Young Oceanic Crust ” and “Old Oceanic Crust”

and drag them into place. Activate Automatic Mode. Under the “View Window” select Both, Show

Labels and Sea Water. Select the “Convergent” Mode and move the “Time Elapsed slider” to a

position just to the right of slow. Press play and observe.

1. What happens to the Old Oceanic plate as the plates converge? IT IS PUSHED

BENEATH.

2. Using the density meter check the density of both plates. How do the densities compare?

DENSITY IN OLD OCEANIC PLATE > DENSITY IN YOUNG OCEANIC

PLATE 3. Why is the Old Oceanic plate subducting under the Young Oceanic plate? OLD

OCEANIC PLATE IS MORE DENSE THAN THE LESS DENSE, MORE BUOYANT YOUNG OCEANIC PLATE.

4. What does the subduction process produce on the Young Oceanic Plate? VOLCANIC

ISLANDS. 5. How are these VOLCANIC ISLANDS being formed? MAGMA ENTERS CRACKS

IN THE CRUST AND PUSHES THROUGH TO BECOME LAVA VOLCANIC

ISLAND. 6. Where are these VOLCANIC ISLANDS located relative to the convergent boundary?

Estimate a distance using the ruler tool as a scale. ~80 km AWAY FROM THE SUBDUCTION ZONE.

7. Locate the trench being created by the convergence of these to plates. Where is the

trench found? TRENCH IS FOUND WHERE THE PLATE CONVERGE.

CONVERGING OCEANIC/OCEANIC PLATES

Sketch the diagram shown in the simulation and label it:

SUMMARY CONVERGING BOUNDARIES

At a convergent plate boundary the plates are moving TOWARDS EACH OTHER. As this

occurs the plates either SCRAPE UP to create mountains or one plate PUSHES under the other to

produce OCEAN TRENCHES and VOLCANIC ISLANDS. When two Continental plates

converge MOUNTAINS are created because the DENSITY of the two plates are DIFFERENT.

When a Continental plate converges with an OCEANIC plate or when a NEW Oceanic plate

converges with an OLD Oceanic plate the HEAVIER, more DENSE plate subducts under the

LIGHTER less DENSE plate. Continental plates are LESS dense than OCEANIC plates and

YOUNG Oceanic plates are LESS dense than OLD Oceanic plates. Subducting convergent

boundaries produce volcanic belts/arcs and parallel mountain chains. Go to the following website

www.iris.edu/hq/files/programs/education_and_outreach/aotm/interactive/6.Volcanoes4Rollover.swf to see

the Continental Volcanic Arc present along the west coast of North America. Earthquakes are a

danger along both collision and subduction convergent boundaries. Earthquakes occurring at a

subducting convergent boundary can produce significant tsunamis.

SUBDUCTION CONVERGING BOUNDARY

TRANSFORM BOUNDARIES

Select the RESET ALL button. Select two pieces of “Continental Crust” and drag them into place.

Activate Automatic Mode. Under the “View Window” select Both, and Show Labels only. Select

the “Transform” Mode and move the “Time Elapsed slider” to a position just to the right of slow.

Press play and observe.

1. What happens to the plates at the Transform Boundary? PAST EACH OTHER IN OPPOSITE DIRECTIONS.

2. Using the density meter check the density of both plates. How do the densities compare?

DENSITY OF THE ONE THAT MOVED AWAY IS GREATER. Repeat these steps using two Young Oceanic Plates and Two Old Oceanic Plates and a Young

Oceanic Plate and an Old Oceanic Plate. Summaize your findings here: FORM TRENCHES WHERE THEY TRANSFORM.

TRANSFORM BOUNDARIES

Sketch the diagram shown in one of the simulations and label it:

SUMMARY TRANSFORM BOUNDARIES

At a transform plate boundary the plates are moving PAST EACH OTHER. These boundaries are

known as strike slip faults and are the location of significant earthquake activity. Haida Gwaii

(The Queen Charlotte Islands) are located just east of a significant transform boundary/fault called

the Queen Charlotte Fault. This fault is on the boundary between the Pacific Plate and the North

American Plate. This is the most seismically active location in British Columbia. Another

significant transform boundary in North America is the San Andreas Fault in California. This fault

is literally shearing California in two.