Continental Drift Lesson

CONTINENTAL

DRIFT

PowerPoint Presentation

Puzzling Coastlines

More than 300 years ago, mapmakers produced the first
world maps. While viewing the maps, the noticed some
continents appeared to fit together like pieces of a jigsaw
puzzle. What do you see?

Pangaea Animation

Click to watch video!

Alfred Wegener

A German scientist and
meteorologist, Alfred
Wegener, noticed
that the coastlines of
particularly South
America and Africa fit
very closely.

1880-1930

Continental Drift

• All continents were once joined

together to form a supercontinent

• He named the supercontinent

Pangaea, meaning all land

• Pangaea began breaking up into

smaller continents and drifted
apart about 200 million years ago

In 1915, Wegener proposed his radical theory
of continental drift:

Multiple Choice

When did Alfred Wegener propose his radical theory about continental drift?

• 1821

• 1915

• 1928

• 1965

Multiple Select

What 2 continents did Wegener notice seemed to fit very closely together?

• Africa

• South America

• North America

• Euprope

The

Breaking

Up of

Pangaea

Multiple Choice

When did Pangea start breaking up?

• Around 400 million years ago

• Around 350 million years ago

• Around 225 million years ago

• Around 150 milion years ago

Evidence for Continental Drift

Alfred Wegener presented
a variety of evidence to
support his hypothesis of
continental drift.
• Similar plant and

animal fossils

• Matching rock types

and mountain chains

• Glacial evidence

Matching Fossils

Fossil evidence for continental drift
includes several of the same organism’s
fossils were found on different landmasses.
• Wegener reasoned that these organisms

could not have crossed the vast ocean
presently separating the continents

• At this time many scientists believed

there were land bridges connecting the
continents, but no signs of land bridges
have ever been found

Matching Fossils

cynognathus

lystrosaurus

mesosaurus

Matching Fossils

Multiple Select

Check all the true statements about fossil evidence.

• Fossil evidence for continental drift includes several of the same organism’s fossils were found on different landmasses.

• Wegener reasoned that these organisms could not have crossed the vast ocean presently separating the continents

• Fossils of the fern Glossopteris indicate all the southern continents were once joined

• There is evidence that there were once land bridges between these continents

Matching Rock Types

Matching rock types in
several mountain belts that
today are separated by
oceans provided evidence
for continental drift.
• Ex. The Appalachian

mountains in coastal North
America are similar in age
and structure as those
found in the British Isles
and Scandinavia.

Multiple Select

Check all that are true about rock evidence.

• Matching rock types are found in several mountain belts that are not connected today.

• The Appalachian mountains in on the east coast of north america are similar in age and structure to those found in the British Isles and Scandinavia.

• The composition of the mountain ranges that seem to match up are actually very different.

Glacial Evidence

Wegener found glacial deposits showing that
between 220 million and 300 million years ago,
ice sheets covered large areas of the Southern
Hemisphere.
• Deposits of glacial till (sediment) occurred at

latitudes that today have temperate and
tropical climates:
• Southern Africa
• South America
• India
• Australia

Glacial Evidence
Glaciers cause grooves in the
Earth’s bedrock as they move
outward.

Grooves and rock deposits left by ancient glaciers are found today on different continents very close to the equator.

Wegener thought that the glaciers were centered over the South Pole and the continents moved to their present positions
later on.

Multiple Select

Check all the statements that are true regarding glacial evidence.

• Wegener found glacial deposits showing that between 220 million and 300 million years ago, ice sheets covered large areas of the Southern Hemisphere.

• Deposits of glacial till (sediment) occurred at latitudes that today have temperate and tropical climates:

• Grooves and rock deposits left by ancient glaciers are found today on different continents very close to the equator.

• Wegener thought that the glaciers were centered over the South Pole and the continents moved to their present positions later on.

Rejection of Wegener’s Hypothesis

Wegener’s hypothesis was rejected by
most other scientists.
• He could explain and provide

evidence that Pangaea once
existed, however he could not
describe a mechanism capable of
moving the continents.
• He could not explain how or why

continents move.

• Scientists who rejected Wegener and

refused to believe that the continents
drifted were referred to as Fixists.

Multiple Choice

True or False - Alfred Wegener's hypothesis about Continental Drift had so much evidence to support it and made so much sense that it was immediately accepted by most other scientists.

• True

• False

Plate Tectonics

Many years later, with new sonar technology, Harry
Hess was able to map the ocean floor using SONAR.
• Earthquake and magnetic field data were also now

available.

• By 1967, these findings led to a new theory called

Plate Tectonics which proved that Wegner was
correct that the continents move.

• Sea-floor spreading was causing

the plates to move.

• Sadly, Wegener was not alive long

enough to see his contributions
come to fruition

Drag and Drop

Once ​

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technology was developed, a scientist named ​

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was able to map the ocean floor. Earthquake and ​

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field data also became available. These new finding supported the original hypothesis by​

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. By 1967 this led to the theory of ​

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Drag these tiles and drop them in the correct blank above

sonar

Harry Hess

magnetic

Alfred Wegener

Plate tectonics