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CHAPTER 17: PLATE TECTONICS

Section 17.1 Drifting Continents

1. Analyze the growth of the continental drift theory by summarizing contributions by

each person in the table below.

Name

Alfred Wegener

Nationality

Austrian

Date Late 1500s

Profession

Observation

Built on matching

coastline

observations by

other people

Built upon

observations by

other people

Proposed

Explanation

2. Create three diagrams to show how it is thought that the continents drifted. Use

figure 17.2 to help you draw what Earth looked like 200 million years ago, 135

million years ago, and in the present.

200 million years ago 135 million years ago present

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3. Analyze the evidence Wegener had supporting his hypothesis of continental drift.

Evidence Concept/Idea Examples of Evidence

Rock Evidence

Fossil Evidence

Climate Evidence

4. Identify 2 reasons why scientists rejected Wegener’s hypothesis of continental drift.

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Section 17.2 Seafloor Spreading

1. Organize information about ocean floor topography by completing the following flow

chart.

2. Predict where the oldest rocks in the Atlantic Ocean are. Predict where the youngest

rocks are. Use maps in your text as a resource.

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3. Imagine you lived 1 million years ago. Predict how you would use a compass for

navigation.

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4. Illustrate magnetic symmetry around an ocean ridge. Use Figures 17.12 and 17.13 to

help you. Show the following features:

-ocean ridge -areas of normal polarity

-areas of reversed polarity -relative ages of rocks

Topographic features on the ocean floor.

Earthquakes

and

volcanoes are

common

Deepest spot

in the ocean

is 11 km

deep.

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5. Organize information about seafloor spreading by completing the following cycle

diagram.

6. Synthesize. Suppose you could measure the distance between New York and London

and between Los Angeles and Singapore over several thousand years. Describe how

those distances would change compared to their distances today.

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Plate moves outward from

the ridge.

Magma pushed into ocean ridge

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Section 17.3 Theory of Plate Tectonics

Plate Boundary

Type

Illustration Plate Movement Associated Geologic

Phenomena

New Features

Formed

Divergent

Convergent

(oceanic-oceanic)

Convergent

(oceanic-continental)

Convergent

(continental-

continental)

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17.4 Causes of Plate Motion

1. Identify the factors that cause convection, describe the movement of a convection

current, and sketch a current.

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2. Compare the processes of ridge push and slab pull by filling in the table below.

Type of plate

boundary

Description of

movement

Impact on plate

tectonics

Ridge Push

Slab Pull

3. Create a diagram to illustrate ridge push and slab pull. Use Figure 17.22 to help you.

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