Plate Tectonics Essay

This essay has a total of 1557 words and 7 pages.

Plate Tectonics



Plate Tectonics
Since the beginning of human kind there has been a cloud of wonder regarding the origin of
our planet. Scientist interested in this field through out the years have developed many
different theories to how our planet came about. Before the Twentieth Century, scientist
and geologist alike revolved in the idea that Mountain building was due to the massive
contractions of the earth caused by the gradual cooling of molten rocks. In 1900, American
scientist Joseph Le Conte, published an article in the Appleton’s Popular Scientific
Monthly. He described that the problem in understanding mountain building was establishing
the cause of sideways pressure. “The most obvious and as yet the most probable view is
that it is the result of the secular contraction of the earth which has gone on throughout
the whole history and is still going on.” (2)

It was not until 1910, that an American Geologist named F.B.Taylor, proposed the idea of a
continental drift. His scientific peers dismissed Taylor’s idea, because there was just
not enough proof. However, Taylor’s idea was then resurfaced by a German scientist named
Alfred Wegener. He proposed that the continents surrounding the Atlantic Ocean, Africa and
South America fit together like a jigsaw puzzle. Wegener was a balloonist, astronomer,
explorer, meteorologist, while in his spare time he researched paleontology, geophysics
and geology. His broad range of studies enabled him to incorporate his theory of Plate
Tectonics. Wegener, later in 1915 while in sick leave from the German military published
his idea that interpreted how his continental drift theory worked. He proposed that a huge
landamass called Pangea, meaning ("all land”) existed 200 million years ago. He furthered
explained that this super continent began to drift apart very slowly throughout millions
of years into what it looks like now. Wegener went on several expeditions through out his
life to the continents of South America and Africa. He came back with evidence to support
his claim of plate tectonics. Wegener and his expedition brought back rock structures,
fossils, and evidence of ancient climates.

When it came to rock structures, Wegener looked for the similarities of the rocks found
along coastlines and the mountain belts found on the continents. They looked at the
mountain belts of the Appalachian Mountains and the Caledonian Mountains in Scandinavia
and the British Isles. These two continuos belts contained similar rock structures and the
ages of these rocks matched the on both ends of the African and South American continents.
Wegener also found evidence of massive climatic changes. He researched and found out that
ancient glacial deposits were found indicating that ice sheets covered a large part of the
Southern Hemisphere, India and Australia. Wegener's explanation of the glaciation was that
the ”landmasses where all fitted together as a super continent with South Africa centered
over the South Pole.” (1.) Pag. 474) He furthered explained that the Northern Hemisphere
was near the equator supporting the idea of coal deposits being located there. Wegener was
more intrigued of the fact that fossilized remains were being found along South America
and Africa. Remains of the aquatic prehistoric dinosaur called Mesosaurus were only found
in eastern South America and Africa. Plant remains were also being found. For example the
fossil fern Glossopteris were found sparingly throughout Africa, Australia, India, and
South America. Furthermore, this plant was found in polar climates, supporting his theory
of connected landmasses. Organisms like the Australian Marsupials and the marsupial
opossums found in the Americas, which have a definite fossil link also supports Wegener’s
theory.

Alfred Wegener’s theories were not immediately accepted by the scientific community. One
of his faults was that he could not prove how the continents moved across the globe.
Wegener’s suggestion was that “tidal influence from the moon”(1. Pag. 475) was to be
credited. However the science community proved him wrong. Eventhough he was in the right
direction, he could not completely and precisely determine how the continental drift was
accomplished. Therefore, his theories were dropped as rubbish. Essentially, Wegener was
ahead of his time. It was not until years later that other scientist cleaned up some of
Wegener’s mistakes and resurfaced the Plate Tectonics theory.

Thanks to the study of magnetism a whole new window of scientific evaluations emerged to
support the theory of Plate Tectonics. S.K. Runcorn proposed an interesting idea. It was
found that “the magnetic alignments in the iron-rich minerals in lava flow of different
ages was found to vary widely.”(1. Pag. 478) This was strong evidence that the magnetic
poles of the earth had migrated through time, meaning that lava flows had moved and so did
the continents. This event is called polar wandering.
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