ES0810_final
12/05/2001
11:38
Page 4
Name
Date
ES0810
How Fast Do Plates Move?
Use another sheet of paper if you need extra space to write complete answers.
1 Which island do you think is youngest?
●
…oldest? Explain your reasoning.
6 Calculate the average rate of plate motion
●
for 0 – 40 million years ago.
Answers will vary. Active volcanoes on Hawaii and
Anxwers may vary.
inactive volcanoes on islands to the northwest indicate
3500 km / 40 million yr ≈ 9 cm/yr
Hawaii is youngest and Nihoa is oldest.
7 Calculate the average rate of plate motion
●
2 What pattern do you see between age of
●
rocks and location?
for 40 – 60 million years ago.
Anxwers may vary.
2300 km / 20 million yr ≈ 11 cm/year
Age of rocks increases with distance northwest of the
island of Hawaii.
8 What does the bend in the chain of
●
seamounts indicate?
A change in the direction of plate motion
●
3 How do you think the chain of islands might
have formed? Explain your idea.
Accept any justified answer. The islands formed as the
volcanoes form over the hotspot as old volcanoes are
responsible for changing the direction of the
Pacific plate’s motion? (What major tectonic
event occurred around 40 million years ago?)
carried northwestward by the plate.
The collision of India into Asia to form the Himalayas.
Pacific plate moved over a hotspot. The plate has moved
to the northwest over the stationary hotspot. New
●
Chapter 8
Internet Investigation
9 What global tectonic event might have been
●
4 How can you use the map information to
calculate the rate (speed) of plate motion
over the hotspot? Describe the information
you need and how you’ll use it.
Information required is the distance the plate has
moved and time over which the movement has
occurred. Distance / Time = Rate
10 What evidence is there of a hotspot currently
●
under Yellowstone National Park?
Geysers indicate a heat source below Yellowstone.
11 In what direction has the North American
●
plate moved over the hotspot under
Yellowstone? Describe your reasoning.
To the southwest. The trail of smooth topography gets
5 Calculate the average rate of the Pacific
●
plate’s motion over the past 5.1 million years.
Express your answer in cm/year.
Answers may vary.
600 km / 5.1 million years ≈ 10 cm/yr
younger to the northeast.
12 Calculate the average rate of the North
●
American plate’s motion over Yellowstone.
Answers may vary.
300 km / 10 million yr ≈ 3 cm/yr
34
Internet Investigations Guide
Earth Science