PANGAEA

1
PANGAEA
In 1912, Alfred Wegener proposed the idea that
the continents were once part of a huge land
mass, called Pangaea (all lands), that later
broke apart.
He was convinced because
1. the continents shape roughly fit together
like a puzzle
2. the rocks and fossils on different continents
matched
His Theory of Continental Drift was ignored
because he could not explain how or why the
plates moved. As a German meteorologist, he
lacked credentials, and he couldnt explain how
huge continents could move.
2
In the early 60s, Harry Hess and J. Wilson,
proposed a mechanism for continental movement,
but they called it geo-poetry to avoid
criticism.
1969 - The Glomar Challenger drilled a series of
holes in the Mid-Atlantic ridge. What they found
revolutionized geology and oceanography!
3
Continental rocks date the Earth at about 4.6
billion years old. Since the ocean floor is
lower in the lithosphere, scientists expected to
find older rocks at those depths.
Continental geologys Law of Superposition states
that oldest rocks are laid down first and should
be found horizontally lowest in a bed unless
uplifted.
4
Instead, they found no rock older than 200
million years old and most were much younger.
How could the ocean floor be younger than the
continents riding on it?
The Deep Sea Drilling Project showed that rocks
became older as they moved away from the MOR.
Oceanic geology showed rock layers are created
vertically - not according to the Law of
Superposition.
5
The MOR seemed to be a parallel distance from
continents on either side.
Core samples revealed matching magnetic striping
in rocks on both sides of MOR.
In 1977, Project FAMOUS, using Alvin,
photographed magma squeezing out of the MOR and
creating new ocean floor.
Scientists, Vine and Matthews, now had the data
for a cohesive theory on plate tectonics.
The sea floor was spreading - moving the
continents with it. The theory of sea floor
spreading explained continental drift. Wegener
was right.