continental drift
TRANSCRIPT
Drifting Continents
http://www.youtube.com/watch?v=TzzGPfVx32M
A. The Theory of Continental Drift1. Alfred Wagener2. All the continents were once
joined together in a single landmass and have since drifted apart
3. Super continent was named Pangaea
4. Continental Drift – Pangaea broke apart and slowly moved toward their present day location
I. The Theory of Continental Drift
Wegener1880-1930
earthobservatory.nasa.gov
Alfred Wegener first proposed the theory of
continental drift.
Did You Know?Wegener’s theory was rejected by
scientists because he could not
explain what force pushes or pulls
continents.
B. Evidence to support the theory
1. Evidence of Landforms – Mountain ranges in South
Africa line up with mountain ranges in
Argentina
Fit of Continents Across the
Atlantic
Mountain ranges in South America line up exactly with those in
Africa!
2. Evidence from Fossils – fossils are any trace of an ancient organism that has been preserved in rock (Example – Glossopteris which is a fernlike plant that lived over 250 million years ago and was found in Africa, South America, Australia, India, and Antarctica)
Notice how fossils lined up across continents!
http://evolution.berkeley.edu/evolibrary/images/history/fossils3.gif
3. Evidence from Climate – Tropical plant fossils found in polar climate and deep scratches in rocks that where formed from glaciers in tropical areas
Did you know... 1. that India was once in the Southern Hemisphere connected to Antarctica? 2. that North America was once surrounded by warm, tropical seas? 3. that Africa was once covered by glaciers, which were kilometers in thickness? 4. that the Sahara desert was once a tropical rain forest?
As North America has drifted to different latitudes, changing climates were
experienced. This shows the changes in the state of New Mexico.
Proof for Changing Climate
At one time, the area that
is New Mexico
(and the rest of
the USA was
below the equator!
• He could not find the force that was causing the continents to drift.
• Because of this, he could not convince anyone that continents could move.
• He died in Greenland on an expedition.
• At the time of his death, no one believed his hypothesis!
Technology developed during the 1940’s changed all that!
Alfred WegenerPangaea
GlossopterisSea floor Spreading
Magnetic pole reversalsProof: Climate, Fossils, Geological
Features
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