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Lecture 2

EESA06H3 Lecture Notes - Lecture 2: Smog, North American Plate, Paradigm Shift


Department
Environmental Science
Course Code
EESA06H3
Professor
Nick Eyles
Lecture
2

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Lecture 2: How Earth Evolves: Continental Drift vs. Plate Tectonics
Key Points:
Formation of planet Earth: 4,500 million years before present
Cotietal drift ad Pangea: 1912 (Alfred Wegener)
o Important to know the difference between continental drift and plate tectonics
“ea floor spreadig: 9 Harold Hess
Mageti stripes o the oea floor ad ader paths for otiets: 9 Fred Vie
Mid-oea ridges ad hot spots: 9 Tuzo Wilso
Computer reconstruction of Pangea 1965 (Edward Bullard)
Plate tetois ad the Wilso le of superotiets: 9 Tuzo Wilso; alled a reolutio
i Earth siees
Continental drift and Pangea:
Continental drift was first discovered in 1912 by Alfred Wegener (meteorologist)
It is original statement that continents drifted away from one big supercontinent into the
continents we have today.
o In the 1960s appliatio of geophsis: e ale to reotel ap uder sea floor ad
underground to map Earth.
o Tuzo Wilson used this data to find out that the plates moved, not continental drift
Wegener proposed that continents moved by plowing through the sea floor Cotietal
Drift
o This hypothesis was rejected by most geologists
Francis Bacon saw how craters were formed and concluded that they were due to impact (e.g.,
craters on the Moon)
Pagea osists of:
o Laurasia (North America and Asia)
o Gondwana (Southern continents)
Laurentia: refers to North America in ancient past
o Laurasia (ancestral North America and Asia)
Wegener set big expedition in Greenland in 1912 he froze.
o His idea of continental drift later died down
Evidence that Wegener used:
Matching rock types of same age from one continent to another to reconstruct supercontinents
o Fossil record of now separated land masses
It is not the change in climate, but the change in position of continents
Continental Ice Sheets:
Natural state for Toronto ~1km deep in ice for 90% of millions of years
The ice from (20,000 years ago) move sediment and debris as it flows and scratching subsurface
(striations)
1960s Ocean Floor Gets Mapped:
find more resources at oneclass.com
find more resources at oneclass.com
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