Let’s Review! a. transfer of heat through liquids and gases = convection b. transfer of heat by physical contact = conduction c. transfer of heat through.

I. Heat flow & Continental drift= convection
= conduction
= radiation
2
A. Continental drift theory
. Alfred Wegener- German Scientist, Wegener purposed that all continents were once joined together in a single landmass & then have slowly drifted apart.
He called his super continent …Pangea
3
4
He first noticed that the continents seem to fit together.
Look at the fit of South America’s east coast and South Africa's west coast.
More Evidence.
Similar landforms
b. coal fields of N. America & Europe line up
6
8
.Another piece of evidence
Continent’s climates have change when the land drifted. What are some clues one might find of past climate?
Lots of evidence that supports CD but did people believe him?
= Convection currents caused by our core.
Convection box demo
Science Exercise: Answer the following questions….
Is there other evidences?
Mid-ocean ridges (MOR)- sea floor spreads & new ocean floor creates underwater mountain chains
East Pacific Rise & Others
Sonar, gravity and magnetics
Appeared to be striped
Polarity reversal were identical on each side of oceanic ridge
1960, Harry Hess proposes sea-floor spreading
Confirmed by mini-Submarine Alvin in 1960’s
Reversed magnetism seen in Rocks.
Final Proof… The age of the ocean bottom.
1968 United State Geologic Survey (USGS)
Deep sea drilling w/ Glomar Challenger
Drilling showed the age correlation in ocean floor rocks.
Where do you think the oldest rocks are located on the sea floor? Youngest?
What's happening at the other end of the sea floor spreading centers????
3. Subduction- process of the ocean floor sinking back into mantle
a. Deep-ocean trenches- deep water canyons in ocean
24