Desultory notes on the government and people of China, and on the ...
Lecture 23 The earth was made so various, That the mind of desultory man, studious of change And...
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Transcript of Lecture 23 The earth was made so various, That the mind of desultory man, studious of change And...
Lecture 23
The earth was made so various,That the mind of desultory man, studious of change
And pleased with novelty, might be indulged
- Wm. Cowper (The Task, 1785)
Plate Tectonics
Webpage for course (daytime)
Webpage for course (nighttime)
Alfred WegnerMeteorologist “Doesn't the east coast of South America fit exactly against the west coast of Africa, as if they had once been joined?” (1910, letter to his fiancee)
http://www.jazclass.aust.com/blog/files/drift.htm
http://geology.com/pangea.htm
Why was Wegner’s ideas not accepted?
Acceptance of Wegner’s theory
Early 1960s
Sea Floor spreading
Subduction
Tests for Wegner’s theorySea Floor spreading
Age of igneous bedrock
Subduction
Benioff zones
Glomar Challenger Deep Sea Drilling Project, 1968-83
JOIDES ResolutionOcean Drilling Program, 1985-2006 refurbished and back at sea, early 2009
Deep Sea Drilling
“continental drift” vs. “plate tectonics
PlatesContinental crust
thicker (~50 km)
older
less dense
Oceanic crust
thinner (~10 km)
younger than 200 myr
more dense
Mix (ex. North American Plate)
MarginsDivergent
Convergent
Transverse
Divergent boundary, Atlantic Oc.
Kevin-drawing, Convergent, Pac.
Convergent, continent-continent
transverse
California