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Transcript of Continental Drift
It is just as if we were to refit the torn pieces of a newspaper by matching their edges and then check whether the lines of print ran smoothly across. If they do, there is nothing left but to conclude that the pieces were in fact joined in this way.
"Doesn't the east coast of South America fit exactly against the west coast of Africa, as if they had once been joined?" wrote Wegener to his future wife in December 1910. "This is an idea I'll have to pursue."
capable of flow
crust & upper mantle
Rich in silica
(light in color - granite)
Less dense, Thicker
Low in silica, rich in iron
(dark in color - basalt)
Thinner, More Dense
Plate: a section of the lithosphere that moves around above the asthenosphere. Can be made of continental and or oceanic crust.
can lead to
Is PA tropical??
Does this look like Antarctica?
fresh water reptile
Did it swim in salt water?
Found new evidence
on the sea floor
The Continental Drift Theory/Hypothesis was developed by Alfred Wegener in the early 1900's. The theory states that all of the continents were once joined in a super landmass called Pangaea (translation = all Earth). Over the last 250 million years Pangaea broke apart into pieces that drifted to their present day locations.
The edges of the the continents seem to fit together like the pieces of a jigsaw puzzle suggesting they were once joined.
Wegener suggested that identical fossils on separate land masses was no coincidence. He hypothesized that they existed and were fossilized when Pangaea was a super land mass. The fossils of Mesosaurus and others were separated as a result of the "drift" of the continents.
*Mesosaurus existed = 270 mya
*Break up of Pangaea = 250 mya
**Think about it!!
PA has extensive deposits of coal indicating that it existed in a climate that was once Tropical. The Theory of Continental Drift asserts that PA was indeed closer to the equator when it was part of Pangaea (see visual above). During this time, the formation of coal began. Over time, Pangaea broke apart and drifted to its current location bringing with it the deposits of coal as evidence of its former location.
Similarly, fossilized remains of the plant Glossopteris have been discovered in Antarctica, an area not conducive to plant growth. These plant fossils are evidence that Antarctica was once located in a warmer area and has since drifted to its present location.
The mountain ranges shown above are of similar age, size and rock type. When reassembled as part of Pangaea, the seemingly separate geologic structures connect to form a continuous mountain chain.
Despite Wegener's efforts, his theory wasn't accepted as true. He had evidence that proved the existence of Pangaea but was unable to discover a force able to move the continents.