Transcript Continental Drift

The Argument for
Continental Drift
Alfred L. Wegener
 Geologist Alfred Wegener
noticed similar rocks & fossil
remains were found on
continents which seemed to
fit together
 He called this “super”
continent called Pangaea
 In 1912 Wegener
published the
first version &
died defending
his theory
PANGAEA
the large landmass that included all of Earth’s
present day continents
Permian
225 million years ago
Triassic
200 million years ago
Jurassic
135 million years ago
Cretaceous
65 million years ago
Present Day
CONTINENTAL DRIFT
http://www.tectonics.caltech.edu/movi
es/outreach/sumatra/pangaea.mov
Support for Continental Drift
1. SHAPE OF THE CONTINENTS
Continents fit together like puzzle pieces
Support for Continental Drift
2. FOSSIL EVIDENCE
SAME FOSSILS: DIFFERENT CONTINENTS
Mesosaurus was incapable of swimming across a large
ocean.
Support for Continental Drift
3. ROCK EVIDENCE – Mountain ranges
 SAME ROCK:
DIFFERENT RANGE
Existing mountain ranges
separated by vast
oceans contain rocks of
identical mineral content.
 A prime example are the
Appalachian Mountains
in the eastern U.S and
the Caledonian
Mountains in the British
Isles.
Support for Continental Drift
4. GLACIAL SCARS
SAME SCARS:
DIFFERENT CONTINENTS
Support for Continental Drift
5. LOCATION OF COAL DEPOSITS
Coal deposits have been found in temperate and polar
regions; however, coal is formed in tropical regions.
CONTINENTAL DRIFT IN DOUBT
Why didn’t people believe in continental drift?
 People couldn’t imagine how the earth could
be millions of years old
 People couldn’t imagine a force great
enough to move the continents
THE
TRUTH!
 North America moves about
1 to 2 centimeters away
from Europe every year.
The Earth’s Crust
 The Earth’s
crust consists
of a number of
Plates
 Plate: large
pieces of the
crust that
moves
 Plate
Tectonics: The
interaction of
the crustal
plates
Convergent
 Convergent = Coming together
 Over riding
plate goes over
the top
 Subducting
plate slides
underneath
 Boundry is the
area where the
two meet
Moving Plates
 Divergent = Moving apart
Moving Plates
 Transform = Moving laterally