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Events leading to the Theory of Plate Tectonics
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Alfred Wegener's Discovery
-After years of researching a subject that he uncovered in a library, Alfred Wegener made his hypothesis public in 1915.
-He claimed that at one point in the past, all the continents were joined forming a super continent or "Pangaea"
-This hypothesis was rejected by the scientific community and Wegener was ignored by his colleagues
-There was no known mechanism that was capable of moving a continent, so his hypothesis was rejected
-This man was ahead of his time, this was just the start! -
Alfred Wegeners Proof of Pangaea
-Alfred travels to west Africa and South America and discovers fossils of the same creatures.
-After this proof, the people of his time weren't exactly convinced, but it would later create interest.
-Fossils also found in North America and Europe.
-When looked at on a map, the pieces fit together with the same types of fossils next to them. -
Ocean floor ridges, but overlooked
-In 1925, Germany sent out a boat to explore the ocean to see if it could be exploited in any way.
-This expedition used echo sounders to record the ocean floor.
-They found what was later announced by American physicists to be the mid-ocean rift.
-This discovery would have backed Wegeners hypothesis but too little was known in the 1920's -
Harry Hess discovers Ocean Floor "mountains"
-During WWII Harry Hess was a submarine commander.
-Part of his assignment was to map out the ocean floor.
-He found out that the pacific ocean had hundreds of "sunken island's" , contradicting what the community knew. -
The Mid-Ocean Rift is Discovered
-American physicists Maurice Ewing and Bruce Heezen found a canyon ridge that the German boat had maped out in the 1920's.
-After a map had been put together of the whole thing, they called it the Great Global Rift.
-This discovery maped out possible locations of what would later be Tectonic plates.
-This discovery inspired Harry Hess to research more. -
Harry Hess Releases Sea Floor Spreading Hypothesis
- In the proccess described by Hess, new floor forms along the mid-ocean ridges. -The old floor sinks back down to the mantle below. -This played a major role in the theory of plate tectonics. -In floor spreading, lava spouts through the cracks to create a new layer.
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Wilson Puts the Puzzle Together with Overall Hypothesis of Plate Tectonics
-He looks at the mid-ocean ridges and says, those could be the edges or "faults" of something bigger that could move continents.
-With information from all the discoveries of the past, he claims that plates are inbetween these ridges and when they move, all land or ocean floor above them can as well.
-The Theory of plate tectonics was born. -
Drilling Ship Glamour Finds Magnetic Material in Ocean Floor
-The ship collected samples of the sediment on both sides of the ridges.
-They find that layers had a reverse magnetic field.
- This proves the theory of sea floor spreading.
-The age of the sediment also proves sea floor spreading.
-The age around the ridge is always young, where the farther out samples are much older. -
Tectonic Plate Theory Becomes More Advanced Over The Years
-Technology allows further reaserch of this theory, with small changes here and there.
-The theory itself was created it 1963 by men who were ahead of their time......
