Transcript Continental Drift PowerPoint

CONTINENTAL DRIFT
http://www.tectonics.caltech.edu/movi
es/outreach/sumatra/pangaea.mov
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
Support for Continental Drift
1. SHAPE OF THE CONTINENTS
Continents fit together like puzzle pieces
Support for Continental Drift
1. SHAPE OF THE CONTINENTS
 Wegener was not the only
one to notice the fit of the
continents.
 1858: Antonio Pelligrini
depicted Africa and South
America connected.
 He was one of the first
scientists to publish maps
depicting the apparent fit of
the continents.
Support for Continental Drift
2. EVIDENCE FROM FOSSILS
SAME FOSSILS: DIFFERENT CONTINENTS
Mesosaurus and Lystrosaurus were incapable of swimming
across a large ocean.
Fossils of the gymnosperm Glossopteris
 Found in all of the
southern continents
provide strong evidence
that the continents
were once a
supercontinent
 (seeds could not travel the great
distances and were too fragile to
survive by a trip across the
ocean)
Support for Continental Drift
3. EVIDENCE FROM LANDFORMS
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
3. LOCATION OF COAL DEPOSITS
Coal deposits have been found in temperate and polar
regions; however, coal is formed in tropical regions.
Support for Continental Drift
4. Evidence of Climate
GLACIAL SCARS- SAME
SCARS: DIFFERENT
CONTINENTS
4. Evidence of Climate (cnt’d)
 Scientists found
evidence of
TROPICAL plants on
the island of
Spitsbergen (which is
now in the Polar
Arctic region.
Spitsbergen must
have been in a
tropical climate at
one time.
CONTINENTAL DRIFT IN DOUBT
Why didn’t people believe in continental drift?
 People couldn’t image how the earth could
be millions of years old
 People couldn’t image a force great enough
to move the continents
BUT by the 1960’s evidence would prove
continental drift is TRUE and…. The story
continues (as does all good science!)