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NAME __________________________ DATE ________ CLASS __________
REINFORCEMENT
Evidence for Continental Drift
Match the items in Column I with the terms or phrases in Column II. Write the letter oj the correct term or phrase
in the blank at the left.
Column I
Column II
1. Reptile fossil found in South America and Africa
a. Alfred Wegener
2. Fern fossil found in Africa, Australia, India, South
America, and Antarctica
h. Appalachians
3. Clues that support continen tal drift
4. Mountains similar to those in Greenland and western
Europe
c. away from the mid­
ocean ridge
d. basalt
e. continental drift
5. An undeIWater mountain range
f. glacial deposi ts
6. Scientist who suggested theory of continental drift
7. Scientist who suggested theory of sea-floor spreading
8. Material that rises to surface at mid-ocean ridge
9. Direction in which ocean floor moves
.."
10. Place where the seafloor is forced down into the mantle
11. Research ship
~ Glomar Challenger
h. Glossopteris
i. Harry Hess
j. magnetic
k. alternating
1. Mesosaurus
12. Age of oldest seafloor rocks
m. mid-ocean ridge
13. Age of oldest continentalrocks
14. Location of youngest seafloor rocks
n. molten material in the
mantle
15. Rock containing iron
o. nearest to ridge
16. Poles that reverse themselves
p. rock, fossil, and climate
17. Magnetic alignment of rocks in mid-ocean ridge
q. sea-floor spreading
18. Process that forms new seafloor
r. almost 4 billion years
19. Movement of continents s. trench
___ 20. Evidence that Africa was once cold t . 160 million years
. (
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Users of Merrill Earth Science have the publisher's permission to reproduce this page.
NAME _ _ _ _ _ _ _ _ _ _ _ _ _ _ DATE _ _ _ _ _ _ CLASS _ _ _ _ _ _ __
ENRICHMENT
Evidence for Continental Drift
STUDYING SEA-FLOOR SPREADING ON LAND
Read the information and study the maps to answer the questions that follow.
You know from your textbook how sea-floor spreading changes the ocean floor. You know that
magma rises at the mid-ocean ridge and flows away from the ridge. In general, this activity is hid­
den beneath the ocean's water. But there is a place where sea-floor spreading can be seen on land.
o
100 km
Key
.'.
~ Active volcanoes; formed from today to
ILLJ 10 000 years ago
D
Formed 10 000 to 2 000 000 years ago
r~:.>\l Formed 2 000 000 to 63 000 000 years ago
FIGURE 1
• Active volcanoes
FIGURE 2
1. What is the name of the landmass through which the mid-ocean ridge in the Atlantic Ocean .
passes? __________________________________________________________________________
2. How does the land of Iceland confirm sea-floor spreading? _____________________________
3. At about what rate does magma (rock) on the eastern side of the ridge on Iceland travel per
year (1 km=lOOOOOOcm)? _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
4. Why do you think geologists might find Iceland a useful place to carry on research on seafloor
spreading? ___________________________________________________________________
56
Copyright Glencoe Division of Mocmilian/McGraw·Hili
Users of Merrill forth Science have the publisher's permission to reproduce this page.
,.
NAME ___________________________ DATE ____
~
______ CLASS ________________
STUDY GUIDE
Theory of Plate Tectonics
In the blank at the left, write the leUer of the term or phrase that best completes each statement.
1. The theory that Earth's crust and upper mantle are broken into sections is called ____ .
h. plate tectonics
a. seafloor spreading
_ _._
2. Plates are composed of the ____ .
a. crust and part of the upper mantle
h. lithosphere and asthenosphere
3. The lithosphere is composed of the __
. __ .
a. plates and seafloor
h. crust and upper mantle
4. Plates float on the
a. asthenosphere
h. lithosphere
5. Plates can
a. pull apart, collide, and move past one another
h. erupt and form precipitation
6. The boundary between two plates that are moving apart is a _. ___ boundary.
a. convergent
h. divergent
7. When ocean plates collide with continental plates, the denser ocean plate ____ .
h. rises
a. sinks
8. The area where a plate descends is a ____ .
h. subduction zone
a. convergent boundary
9. A ____ is created where one plate moves under another.
a. mantle .
h. trench
10. A subducted plate melts, forming ____ .
a. magma and volcanic mountains
h. the lithosphere
11. Two continental plates may collide and cause ____ .
a. glaciers
h. earthquakes
12. Scientists think plates are moved by ____ .
h. volcanoes
a. convection curren ts·
13. A place where plates slide past one another is a ____ .
h. transform fault
a. divergent fault
14. The San Andreas fault is a
a. volcano ·
h. transform fault
15. The Himalayas were formed at a ___ .
a. convergent boundary
h. transform fault
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.. ~~---
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NAME _ _ _ _ _ _ _ _ _ _ _ _ _ _ DATE _ _ _ _ _ _ CLASS _ _ _ _ _ _ __
REINFORCEMENT
Theory of plate Tectonics
Use the words in the box to fill in the blanh
asthenosphere
convection current
lithosphere
plates
plate tectonics
1. The theory of ______________ states that Earth's crust and upper mantle are
broken into sections.
2. These sections, called ______________ , are composed of the crust and a part of
the upper mantle.
3. The crust and upper mantle are called the ______________
4. Beneath this layer is the plasticlike _ _ _ _ _ _ _ _ _ _ _ __
5. Many scientists think hot plasticlike rock is forced upward toward the surface, cools, and sinks.
This process is called a ______________
Four diagrams are shown in the table below. Explain each diagram to complete the table.
Diagram
. Type of boundary
and motion at boundary
Diagram
6.
8.
7.
9.
II<Ar<
Type of boundary and
motion at boundary
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