CLASS COPY – Please do NOT write on this paper. Return this sheet at the end of the class period.
READING 5: Digging Deeper: Development of the Plate Tectonics Theory
[ EarthComm Book pages G110-68-G72 ]
Directions:
Read the tasks presented below for each section of the article. This will give you a reason for
your reading. Then read the corresponding section of the article in your textbook. Record your responses in your
science notebook, being sure to include a title, date, and any other information you need to make a helpful
entry. Remember – you will be allowed to use your science notebook on the unit test.
Development of the Plate Tectonics Theory
1. Edward Suess explained the Earth’s origins in the 1800s. According to him . . .
a. . . . how were the mountains formed?
b. . . . how can you explain the same fossils on separate continents?
c. . . . how were land bridges supposedly formed and lost?
2. Alfred Wegener challenged the ideas of the contraction theory in his hypothesis of continental
drift.
a. What was the observation of the Alps he used as evidence?
b. What effect did the discovery of radioactive heat have on supporting or disproving his
theory?
3. What was Wegener’s evidence for the supercontinent of Pangea?
4. As scientists first mapped the ocean floor they originally found evidence to support continental
drift, but eventually the evidence led to the theory of plate tectonics. What was the big
difference between the two?
5. To identify continents before Pangea we have to look at old continental crust.
a. What do the Urals and Appalachians show?
b. What do rocks and fossils show?
c. What is the Wilson cycle?
Paleomagnetism
6. What is believed to cause the Earth’s magnetic field?
7. Why are there no longitude lines on the map of Pangea?
CLASS COPY – Please do NOT write on this paper. Return this sheet at the end of the class period.
Summary Chart of: READING 5: Digging Deeper: Development of the Plate Tectonics Theory
Who proposed it?
Describe continental
movement
Explain the same fossils
on different continents
Explain Mountain folds
Contraction
Continental Drift
Plate Tectonics
Copy the chart into your notebook. Use the following terms or phrases to fill in the empty blocks. If a phrase is listed twice
below, then it is used twice in the chart.
Continents collide and bend the rock
layers
Contraction of the cooling surface
like an apple drying
Sea floor spreading and subduction,
propelled by convection
Continents collide and bend the rock
layers
Land bridges allowed migration but
have long since sunk to the ocean
floor
Edward Seuss
Continents plow through ocean
basins
Continents were together in Pangea
Continents were together in Pangea
None horizontally, but they rise and
fall vertically as the Earth cools
Alfred Wegener
J.T. Wilson
CLASS COPY – Please do NOT write on this paper. Return this sheet at the end of the class period.
Development of the Plate Tectonics Theory
1. Edward Suess explained the Earth’s origins in the 1800s.
a. According to him, how were the mountains formed? As the Earth cooled and shriveled ridges formed like a dried apple
b. According to him, how can you explain the same fossils on separate continents? Land bridges allowed migration, but they have
since sunk.
c. How were land bridges supposedly formed and lost? They rise and fall as the Earth cools and shrinks
2. Alfred Wegener challenged the ideas of the contraction theory in his hypothesis of continental drift.
a. What was the observation of the Alps he used as evidence? The layers of rock are folded like in a collision.
b. What effect did the discovery of radioactive heat have on supporting or disproving his theory? The radioactive heat shows the
Earth isn’t really cooling, but rather the surface is subject to convection from below.
3. What was Wegener’s evidence for the supercontinent of Pangea? Fossils, matching rocks and minerals, cuts in mountain ranges such as the
Appalachians.
4. After World War II as scientists mapped the ocean floor they originally found evidence to support continental drift, but eventually it led to
the theory of plate tectonics. What was the big difference between the two?
In PT the sea floor spreads and subducts, where in the drift theory the continents randomly plow their way through the crust.
5. To identify continents before Pangea we have to look at old continental crust.
a. What do the Urals and Appalachians show? Old compression line
b. What do rocks and fossils show? Old matchups
c. What is the Wilson cycle? Cycle of forming and reforming super-continents
CLASS COPY – Please do NOT write on this paper. Return this sheet at the end of the class period.
Paleomagnetism
6. What is believed to cause the Earth’s magnetic field? Outer core flowing over the inner core
7. Why are there no longitude lines on the map of Pangea?
Evidence shows latitude of past fossils but not their longitude
Contraction
Who proposed it?
Describe continental
movement
Explain the same fossils
on different continents
Explain Mountain folds
Seuss
None horizontally
Land bridges allowed
migration but have long
since sunk to the ocean
floor
Contraction of the cooling
surface like an apple
drying
Rise and fall vertically as
the Earth cools
Continental Drift
Wegener
Continents plow through
ocean basins
Continents were together
in Pangea
Continents collide and
bend the rock layers
Plate Tectonics
Everyone
Sea floor spreading and
subduction, propelled by
convection
Continents were together
in Pangea
Continents collide and
bend the rock layers