Plate Tectonics
Alfred Wegener-German Scientist who noticed that the African and south American
coastlines on opposite sides of the Atlantic Ocean seemed to fit as if they were adjacent
pieces of a jigsaw puzzle
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African and South American Coastlines match
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Other continents also seemed to fit together
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Noted that fossils were found on one continent and then on another but no where
else in world
o
of Mesosaurus were found in Argentina and Africa but nowhere else in the world
o
Cynognathus, a Triassic reptile, lived in Brazil and Africa
o
Remains the Lystrosaurus were found in Africa, Antartica and India
o
Fossil ferns, Glossopteris, were found in all the southern land masses
"Plotted glacial deposits (250-million-year-old)
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Sedimentary Rocks form in specific climate zones-depends on latitude. So the
type of rock reflects the latitude at which it was formed.
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Glacial rock is found at the equator-clearly could not have been originally formed
there.
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Came up with idea of Pangea
o
Pangea from the Greek root words for "all lands"
o
Northern part = Laurasia
o
Southern part = Gondwanaland
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Wegener was the first to peruse this topic in 1910-1930
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Continental Drift-Wegener's concept of a single supercontinent that broke apart to
form the modern continents
I.
How Does Plate Tectonics Work?
a) Lithosphere
- shell of hard strong rock
- floats on the hot, plastic athenosphere
- broken into seven large segments called Tectonic Plates
- the tectonic plates horizontally glide over the
athenoshpere at rates ranging from 1 to 16
centimeters per year (like ice drifting across a pond)
- continents and ocean basins make up the upper parts of the plates
- as the plates glide, the ocean and continents move
with it
II.
Theory
The concept that the lithosphere floats on the asthenoshpere, and is
segmented into seven major tectonic plates, which move relative to one
another by gliding over the asthenosphere. Most of the Earth’s major
geological activity occurs at plate boundaries.
Three types of plate boundaries exist:
1. Divergent
2. Convergent
3. Transform