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CRCT Question . A break in Earth’s crust where rocks have slipped past each is a ______. a. fault b. plate c. boundary d. crack. Corny Joke of the Day. Why did the bird go to the doctor? For Medical Tweet- ment. Tier 1 CD= End of Class. Drifting Continents.
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CRCT Question A break in Earth’s crust where rocks have slipped past each is a ______. a. fault b. plate c. boundary d. crack
Corny Joke of the Day Why did the bird go to the doctor? For Medical Tweet-ment
Tier 1 CD= End of Class
Drifting Continents http://www.youtube.com/watch?v=TzzGPfVx32M
I. The Theory of Continental Drift A. The Theory of Continental Drift • Alfred Wagener • All the continents were once joined together in a single landmass and have since drifted apart • Super continent was named Pangaea • Continental Drift – Pangaea broke apart and slowly moved toward their present day location
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.
Wegener searched and found three main pieces of evidence. Geologic - evidence in the layers of rocks across continents Fossil - evidence in the places certain fossils are found Climate - evidence in the changing climates during the past
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 AtlanticMountain ranges in South America line up exactly with those in Africa! Geologic Evidence
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)
Fossil Evidence http://evolution.berkeley.edu/evolibrary/images/history/fossils3.gif Notice how fossils lined up across continents!
3. Evidence from Climate – Tropical plant fossils found in polar climate and deep scratches in rocks that where formed from glaciers in tropical areas
Climate change 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?
Proof for Changing Climate At one time, the area that is New Mexico (and the rest of the USA was below the equator! As North America has drifted to different latitudes, changing climates were experienced. This shows the changes in the state of New Mexico.
Wegener's problem • He could not find theforcethat 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!
Tier 1 Must have Alfred Wegener Pangaea Glossopteris Sea floor Spreading Magnetic pole reversals Proof: Climate, Fossils, Geological Features