ES 9.1 Continental Drift

PrenticeHall
EARTH SCIENCE

TarbuckLutgens
◆

Chapter
9

Plate Tectonics

1. Read section 9.1: Continental Drift on pages 248-253 in the text.

2. Taken notes over section 9.1, writing all key concepts and defining all key terms.

​Be sure you have...

An Idea Before Its Time

9.1 Continental Drift

◆Wegener’s continental drift hypothesis stated that the continents had once been joined to form a single supercontinent.

• Wegener proposed that the supercontinent, Pangaea, began to break apart 200 million years ago and form the present landmasses.

​Key Terms: continental drift, Pangaea

Breakup of Pangaea

An Idea Before Its Time

9.1 Continental Drift

◆Evidence

1. The Continental Puzzle

   1. The "jigsaw fit" of the continents

2. Matching Fossils

   1. several fossil organisms found on different landmasses.

   2. example: Mesosaurus fossils found in South America and Africa.

An Idea Before Its Time

9.1 Continental Drift

3. Rock Types

   1. Rock evidence for continental drift exists in the form of several mountain belts that end at one coastline, only to reappear on a landmass across the ocean.

Matching Mountain Ranges

An Idea Before Its Time

9.1 Continental Drift

4. Ancient Climates

   1. Wegener found glacial deposits showing that large ice sheets covered large areas of the Southern Hemisphere.

   2. Evidence of glacial till in southern Africa, South America, India, and Australia.

Glacier Evidence

Multiple Choice

Which of the following was NOT an evidence Wegener used to support his theory of continental drift?

• Rock Types

• Ancient Climates

• Fossil Evidence

• Similar Climates

Rejecting the Hypothesis

9.1 Continental Drift

◆A New Theory Emerges

• Wegener's Theory of Continental Drift was rejected.

• The main objection to Wegener's hypothesis was that he could not describe a mechanism capable of moving the continents.

Years later, a new theory called plate tectonics was proposed and accepted.

Review Key Concepts

9.1 Continental Drift

• What is the theory of continental drift?

• List the evidence that supported the theory of continental drift.

• Why was Wegener's continental drift hypothesis rejected?

• What was Pangaea?

Key Terms

9.1 Continental Drift

• Pangaea

• continental drift