Lab 11A - 1
Name:
Stamps
Section:
Due Date:
Plate Tectonics Lab
Group Member’s Names:
1.
2.
3.
Activity #1:
Familiarize Yourself with the Data
The maps on the right illustrate the major
features on the ocean floor (the mid-ocean ridge
and trenches), and the global distributions of
earthquakes and volcanoes.
1. In the top picture, highlight the ocean
“spreading centers” (the mid-ocean ridge)
with a red pencil and the trenches with
a green pencil.
2. Are earthquakes common or rare
near ocean “spreading centers”
(the mid-ocean ridge)?
________________________
3. Are earthquakes common or rare
near ocean trenches?
________________________
4. Are active volcanoes common or rare
near ocean trenches?
________________________
5. Highlight the chain of active volcanoes around the edge of the Pacific Ocean in red.
What do we call the chain of volcanic mountains
and islands around the edge of Pacific Ocean?
______________________________
Activity #2: Density of Continental
and Oceanic “Crust”
Lab 11A - 2
If another group is doing the experiment,
begin on Activity #3, and do Activity #2
when they are finished.
In this experiment, you will measure the density of the rock making up the continental crust and
oceanic crust (the “crust” is the top part of the lithosphere, the solid outer layer of the Earth).
6. What kind of rock is continental crust made of?
________________________
7. What kind of rock is oceanic crust made of?
________________________
8. Identify the two rock samples. In other words, which one is basalt? Which is granite?
How can you tell them apart?
9. Measure the mass (weight) of each rock sample in grams
and record them in the table below.
10. Measure the volume (size) of each rock sample in cubic centimeters (cm3)
and record them in the table below.
Procedure:
 Fill the beaker up to the 300-ml line.
 Put the rock in the beaker.
1 milliliter (ml) is equal to
1 cubic centimeter (cm3)
 Read off the level of the water in the beaker. The volume of the rock is the level of
the water in the beaker minus 300 ml. (You might pour the water above the 300-ml
line into the graduated cylinder – the tall, thin container – to make a more precise
estimate of the volume of the rock.)
 Remove the rock from the beaker and dry it off.
Mass
(grams)
Volume
(cm3)
Density
(g/cm3)
Basalt
Granite
11. Using your measurements, calculate the density of each rock.
Show your work in the space provided in the table above. Circle your answers.
12. Which kind of crust has a higher density,
continental crust or oceanic crust?
________________________
Lab 11A - 3
Activity #3: Case Studies in Plate Tectonics
Hint: A variety of figures in your textbook and notes may be useful for answering these
questions. I recommend figure 2.10 on p. 44 in particular. Figure 2.22 on p. 58 is useful
for the first question, and figure 2.20 on p. 55 and figure 2.23 on p. 59 are also useful.
13. At the mid-ocean ridge,
are the plates moving apart
or towards one another?
Mt. Everest, the
world’s tallest
mountain, is
found in the
Himalayas, the
tall mountains
north of India.
_________________________
14. Outline the mid-ocean ridge in red in the
figure below. Put red arrows on the map
near the mid-ocean ridge showing the
directions in which the Earth’s crust
is moving.
15. Draw a green line through the mountains
representing the place where the Indian
plate is meeting the Eurasian plate.
India
16. Why are Mt. Everest and the Himalayas
so tall? Explain how and why the
motion of the plates creates them.
At the location of Mt. Everest, the plates
are moving Away From / Towards
one another. Neither plate subducts under the other plate and down into the mantle
because both plates are made of _____________________ which has a density that
is much ___________________ than the density of Basalt / Granite / the Mantle,
so neither plate can sink down into it. Since the plates cannot go Up / Down
when they smash together, the only direction the plates can go is Up / Down,
which creates _________________________________________________.
17. Label the figure on the right showing the
plates near Mt. Everest and the Himalayas.
● Put an arrow on each plate
showing its direction.
● Write “basalt” or “granite” on each plate.
● Label the mantle, and draw arrows
in it showing the direction in which
the magma is flowing.
● Label Mt. Everest and the Himalayas.
Lab 11A - 4
18. Outline the trench in green in the figure below. Put green arrows on the map on both
sides of the trench showing the directions in which the Earth’s crust is moving.
19. At the location of the Mariana Trench,
are the plates moving apart
or towards one another?
__________________________
20. Why is the plate on the right
(the eastern plate), subducting
at the trench?
The Mariana Trench,
the deepest place in
the world, is found
next to a chain of
volcanic islands called
the Mariana Islands.
Both plates are made of
___________________________,
but the plate on the right is
Younger / Older than the
plate on the left, so it has a
___________________________
density than the plate on the left,
because______________________________________________________________
____________________________________________________________________
21. What is a trench? _____________________________________________________
How or why does the collision of these two plates create a trench?
22. Why are there islands next to the Mariana Trench?
Explain how and why the motion of the plates creates them.
23. Label the figure on the right showing
the plates near the Mariana Trench.
● Put an arrow on each plate showing its direction.
● Write “basalt” or “granite” on each plate.
● Label the mantle, and draw arrows in it showing
the direction in which the magma is flowing.
● Write “melting” in red where a plate is melting,
and show the lava rising up through the other plate.
● Label the Mariana Trench and the Mariana Islands.
Lab 11A - 5
24. Outline the mid-ocean ridge in red, the trench in green, and the (transform) faults in blue
in the figure below. Put red arrows on the map near mid-ocean ridge showing the
directions in which the Earth’s crust is moving, and put green arrows near the trench
showing the directions in which the Earth’s crust is moving.
25. At the trench off the coast of Northern
California, Oregon, and Washington,
are the plates moving apart
or towards one another?
__________________________
26. Why is the plate on the left
(the western plate) subducting
at the trench?
Mount St. Helens
The plate on the left is made of
___________________________,
and the plate on the right is made of
San Francisco
___________________________,
Los Angeles
When they meet, the plate on the left
dives below the plate on the right
because:
27. Why
W are there so many volcanoes (e.g., Mount St. Helens) in the Pacific
Northwest near the coast and the trench? Explain how and why the motion
of the plates creates them.
28. Label the figure on the right showing the plates
near the trench in the Pacific Northwest and
Mount St. Helens.
● Put an arrow on each plate showing its direction.
● Write “basalt” or “granite” on each plate.
● Label the mantle, and draw arrows in it showing
the direction in which the magma is flowing.
● Write “melting” in red where a plate is melting,
and show the lava rising up through the other plate.
● Label the trench and Mount St. Helens.
Lab 11A - 6
29. Outline the mid-ocean ridge in red and transform faults in blue in the figure below.
Put red arrows on the map by the mid-ocean ridge showing the directions in which the
Earth’s crust is moving.
30. At the mid-ocean ridge,
are the plates moving apart
or towards one another?
__________________________
Mexico
(mainland)
A
31. Why are the plates moving apart
or towards one another?
Baja
California
B
32. Label the figure on the right
showing the plates along the
dotted line A-B.
● Put an arrow on each plate
showing its direction.
● Write “basalt” or “granite”
in appropriate places
on each plate.
● Label the mantle, and draw arrows
in it showing the direction in which
the magma is flowing.
● Label the mid-ocean ridge, Baja
California, and the mainland of Mexico.
33. Is the distance between the mainland of Mexico
and Baja California getting larger, smaller,
or staying the same?
__________________________
34. It is sometimes said that after a big earthquake, California will “fall into the ocean.”
When Southern California and Baja California finally break away from
North America, will they (the land) sink below sea level? Why or why not?
(Hint: Discuss the layers of the Earth: lithosphere/crust, mantle.)
Lab 11A - 7
Activity #4: Sediment Cores and Plate Tectonics
A sediment core was obtained from 15oN, 150oW. The location labeled “1st” along the midocean ridge is the place where the basalt cooled from lava into solid ocean crust and the 1st layer
of sediments began piling up on the new ocean floor. The location labeled “3rd” is the current
location of the sediments. The arrow shows the motion of the Pacific plate over time.
3rd
Ridge
2nd
1st
Sediment
Core
Today
Sediment
Core
Equator
20 mya
Ridge
MOR
Siliceous
Ooze
100
1st
2nd
200
28 mya
300
400
Calcareous
Ooze
depth below seafloor (meters)
0
Red Clay
3rd
Ocean Crust
42 mya
Basalt
35. Which kind of sediment piled up first? second? third? Label the
core accordingly. (In other words, write 1st, 2nd, & 3rd next to the
sediments of the core.)
Don’t forget to answer
this question!
The basalt is not a
layer of sediments.
What is it?
Lab 11A - 8
All 3 kinds of sediments (calcareous ooze, red clay, and siliceous ooze) fall to the ocean bottom
everywhere in the ocean, so ocean sediments are mixtures of different sediments. However,
often one kind of sediment dominates. In other words, more of one kind of sediment reaches the
bottom than either of the other two kinds of sediments in different places on the ocean floor.
36. Where did the calcareous ooze layer build up?
The Equator / The Mid-Ocean Ridge / Near Hawaii
Under what conditions did the calcareous ooze layer build up?
Beneath (A)_____________ surface water
Possible Answers
A: Warm, Cold
B: Not Too Deep,
Somewhat Deep,
Very Deep
where the ocean was (B)________________________________.
Why is a lot of calcareous ooze able to reach the ocean floor
at this location and under these conditions?
Discuss BOTH
water temperature
AND depth.
Why does very little of siliceous ooze reach the ocean floor at this location
and under these conditions?
Why does very little red clay reach the ocean floor at this location
and under these conditions?
37. Where did the siliceous ooze layer build up?
The Equator / The Mid-Ocean Ridge / Near Hawaii
Under what conditions did the siliceous ooze layer build up?
Beneath (A)_____________ surface water
where the ocean was (B)________________________________.
Why is a lot of siliceous ooze able to reach the ocean floor
at this location and under these conditions?
Discuss BOTH
water temperature
AND depth.
Why does very little of calcaerous ooze reach the ocean floor at this location
and under these conditions?
Why does very little red clay reach the ocean floor at this location
and under these conditions?
Lab 11A - 9
38. Where did the red clay layer build up?
The Equator / Mid-Ocean Ridge / Near Hawaii
Under what conditions did the red clay layer build up?
Where the ocean was (B)____________________________.
Why is red clay the only kind of sediment that can build up at this location
and under these conditions?
39. Why is the layer of siliceous ooze so much thicker than the layer of calcareous ooze?
In other words, why are more silica shells sinking to and reaching the ocean bottom at
location #2 than the number of calcium-carbonate shells that are sinking to and reaching
the ocean bottom at location #1?
40. Why is the layer of red clay so much thinner than the other two layers? In other words,
why does very little red clay sink to and reach the ocean bottom in location #3?
41. The sediments found in this sediment core are evidence that supports the theory of plate
tectonics. To see why, suppose that the ocean floor did not move away from the midocean ridge. (In other words, suppose that the theory of plate tectonics was incorrect.)
In this case, what would the sediment core dug up from location #3 look like?
In other words, what kind of sediments would we have found there?
Explain your reasoning.
The fact that the sediments at location #3 do not match those you described in your answer to the
previous question demonstrates that the ocean floor has not remained in one spot; they
demonstrate that the ocean floor has moved. More than that, the sequence of the sediments in
the core actual verifies that the sea floor is moving away from the mid-ocean ridge.
Lab 11A - 10