Earth Science- Unit 2, Dynamic Earth
Name: ______________________
Unit 2- The
Earth Science- Unit 2, Dynamic Earth
Name: ______________________
Unit 2 VocabContinental drift
Mid-Atlantic Ridge
Mid-Ocean ridges
Seafloor spreading
Plate tectonics
Oceanic crust
Continental crust
Divergent boundary
Rift valley
Convergent boundary
Subduction zone
Ocean trench
Transform boundary
Convection current
Elastic rebound theory
Pacific Ring of Fire
P waves
S waves
Surface waves
Mercalli scale
Earth Science- Unit 2, Dynamic Earth
Name: ______________________
Hot spots
Mafic lava
Felsic lava
Shield volcanoes
Cinder cones
Composite volcanoes
Insert sea floor spreading lab from
Earth Science- Unit 2, Dynamic Earth
Name: ______________________
Sea Floor Spreading Lab- Part 2
In the last few decades, scientists have discovered both age and magnetic patterns in the seafloor, which is
further evidence for plate tectonics. This evidence shows that new seafloor has been forming for millions of
years at mid-ocean ridges throughout the oceans. Magma melted within the crust rises to the seafloor, cools
and solidifies into new rock. In some places this new seafloor is pulled apart by movement of the asthenosphere
under the plates, forming two rock masses which move slowly apart from the ridge. Geologists call this seafloor
Elsewhere, one plate slides under another, or subducts, and deep ocean trenches are formed. This is called a
subduction zone and happens at converging boundaries. Rock on the subducting plate becomes part of the
asthenosphere. Oceanic crust is denser and thinner than continental crust, so all seafloor rock is eventually
destroyed in this way. Thus, the oldest seafloor rocks are only 180 million years old, but the oldest continental
rocks, which cannot be pulled into the trenches, are as old as 4,000 million years, or 4 billion years.
Background Questions:
1. What pulls the new seafloor apart in opposite directions?___________________________________
2. Where are trenches formed?_______________________________________________________________
3. How old is the oldest seafloor?______________________________________________________________
4. How old is the the oldest continental rocks?_________________________________________________
5. Why are the continental rocks so old?______________________________________________________
1. Cut out the strips from the paper and then from each other. Tape the strips together at the label point
so that they face each other.
2. On the model base, cut the lines at A, B, and C.
3. Thread the strips up through slit B and out to slits A and C.
4. Pull the strips apart and watch what is occurring at the slits.
Analysis Questions:
1. Is the rock labeled A the oldest or youngest?
Earth Science- Unit 2, Dynamic Earth
Name: ______________________
2. Is the mid-oceanic ridge at SLIT B or SLITS A& C?
Underline one: At this boundary are plates coming together or pulling apart?
Is this called converging or diverging?
3. Is the rock layer labeled B the oldest or youngest?
4. Is the subduction zone with ocean trenches at SLIT B or SLITS A& C?
Are the plates at this boundary converging or diverging?
5. New seafloor rock is continually being formed at mid-ocean ridges and destroyed at
trenches in subduction zones. Rock is formed on the continents, but then pushed up into mountains. Which rock
will be older, continental or ocean floor?
6. Ocean plates slide under continental plates.
Which are denser, oceanic plates or continental plates?
Which are thicker (Review background material)?
7. Look at the map, which is part of the lab and look at the map key at the bottom. Pick a color for convergent
boundaries and use it on the symbol in the key. Color all convergent boundaries that color on the map.
Five of these features are formed at convergent boundaries. Remember that earthquakes can happen
wherever plates move. Circle the 5 features:
volcanic islands
volcanic mountain chain
mid-ocean ridge
rift valley
non-volcanic mountain range
8. Repeat step 7 for divergent boundaries.
Four of these features are always formed at divergent boundaries. Circle them:
Earth Science- Unit 2, Dynamic Earth
volcanic islands
Name: ______________________
volcanic mountain chain
rift valley
mid-ocean ridge
non-volcanic mountain range
9. Color the transform boundaries a third color on the map and key.
10. What kind of mountains are formed when from the magma when 2 pieces of ocean crust separate,
volcanic, or non-volcanic?
11. Circle the Mid-Atlantic Ridge, and Iceland on your map. What kind of boundary is this, divergent or
12. One of the keys to plate tectonics was the discovery that the Earth's magnetic field has reversed its polarity
170 times in the last 80 million years. As new basaltic material is squeezed up into the mid-ocean cracks and
solidifies, it is magnetized according to the polarity of the Earth's magnetic field. If the field reverses its polarity,
the strip of new material is magnetized in an opposite sense. As the oceanic floor continues to spread, the new
strips of rock are carried away on either side like a conveyer belt.
On your model, the alternating black and white bands show the reverses in polarity. Describe what it
looks like on both sides of the Mid-Ocean Ridge and why it is that way?
Earth Science- Unit 2, Dynamic Earth
Rock Layer A
Name: ______________________
Rock Layer A
Earth Science- Unit 2, Dynamic Earth
Name: ______________________
Rock Layer B
Rock Layer B
Tape Here
Tape Here
Slit A
Earth Science- Unit 2, Dynamic Earth
Name: ______________________
Slit B
Slit C
Evidence for plate tectonics lab from
Earth Science- Unit 2, Dynamic Earth
Name: ______________________
Earth Science- Unit 2, Dynamic Earth
Name: ______________________
Triangulation Virtual Lab
Directions: Navigate to
Read the introduction before moving on. Answer these Pre-lab questions:
1. What is the point of origin of an earthquake called?
2. What type of instrument measures earthquake activity?
3. What is a seismic wave?
4. Compare S and P waves.
5. The speed of an earthquake is dependent on what?
6. How is an earthquake’s epicenter located?
A) Procedure: First, choose the San Francisco area at the bottom of the page and click on ‘Submit choice’
B) Read how to measure the S-P interval and click on View Seismographs
C) Predict the S-P intervals for the 3 seismographs on the next page
o Predictions: ______ sec _______ sec ________ sec
D) Click on ‘Convert S-P Intervals’ at the bottom of the page
E) Use the S-P graph to the left and the estimates you made for the S-P time intervals for the three
S-P Interval (sec)
Epicenter Distance (Km)
F) Next, click on ‘Find Epicenter’
G) How well did you do?
H) If you get an ‘Oops!’, Re-measure the S-P intervals until you get a better measurement.
Earth Science- Unit 2, Dynamic Earth
Name: ______________________
I) When you have a close enough measurement, click on the ‘View True Epicenter’ button and fill in the
following table:
Your Data
Actual Data
Recording Station S-P Interval Epicentral Distance S-P Interval Epicentral Distance
Eureka, CA
Elko, NV
Las Vegas, NV
Next, click on the ‘Compute richter magnitude’ button at the bottom of the screen.
After you read the introduction, click on the ‘Go to next page’ button
Practice reading the seismographs to find the amplitude of the S wave.
What was your guess for the magnitude on the Richter scale? What was the actual magnitude?
Now, Go back to the main page and choose 2 more locations. Follow steps C-M with the two locations of your choice
and fill in the following information:
Location Choice #2: ___________________________
Your Data
Actual Data
Recording Station S-P Interval Epicentral Distance S-P Interval Epicentral Distance
Actual Richter Magnitude= ______
Location Choice #3: ___________________________
Your Data
Actual Data
Recording Station S-P Interval Epicentral Distance S-P Interval Epicentral Distance
Actual Richter Magnitude= ______
Earth Science- Unit 2, Dynamic Earth
Name: ______________________
Will the citizens of Uhohh, Japan Survive?
A once-dormant volcano just outside of the city of Uhohh, Japan has recently been
experiencing some volcanic activity. Experts say that the volcano just started to
erupt minutes ago. The evacuation process has already begun in Uhohh, but it will
take a full 24 hours for the city to be completely evacuated.
This volcano is a cinder cone volcano and is located 4.3 Km outside of Uhhoh. The angle of incline is roughly
25°. This volcano is known for containing felsic lava, which is a lighter color lava. This lava is a lot like silica, and
is known to have similar properties as oil when completely heated.
With the above information, it is up to your group to design an experiment to see if the citizens Uhohh, Japan
will have enough time to evacuate their city before the lava reaches its boarders. You will design your own
experiment using the possible materials below. After you have conducted your experiment and collected data,
you will put together a lab report in order to share your findings.
Need-to-know Equations:
1 Km= 100000 cm
1 second= 0.000278 hours
Speed= Distance/Time
Possible materials:
Masking tape
1. First discuss the experiment with your group. Come up with a hypothesis:
2. Next, start making an outline of your procedure. What steps will you take? What materials will you need?
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