Friday 19 June 2015

Plate Tectonics


1)     What was believed BEFORE continental drift.
-Find one theory from Pre-1910 that describes how humans explained such phenomena as earthquake, volcanoes, mountains, etc.
The speculation that continents might have 'drifted' was first put forward by Abraham Ortelius in 1596. The concept was independently and more fully developed by Alfred Wegener in 1912, but his theory was rejected. In 1858 Antonio Snider-Pellegrini created two maps demonstrating how America and Africa continents might have once fit together. Antonio Snider-Pellegrini, and others had noted earlier that the shapes of continents on opposite sides of the Atlantic Ocean,mostly Africa and South America, seem to fit together.

2)     The theory of Continental Drift
-          Who came up with it?
-          When did they come up with it?
-          What did it state? What was the evidence?
-          Was the theory accepted? Why or why not ?
In 1915, the German geologist and meteorologist Alfred Wegener first proposed the theory of continental drift, which states that parts of the Earth's crust slowly drift atop a liquid core. Wegener hypothesized that there was a gigantic super continent 200 million years ago, which he named Pangaea.Wegener published this theory in his 1915 book, On the Origin of Continents and Oceans. The evidence was the fossils in the ground. Some fossils from south america were in Africa which proved Pangaea truly did exist. However his theory was rejected because there was no explanation as to why/how the continents would have split up and drifted apart from the super continent Pangaea.

3)     The Theory of Plate Tectonics
-          Who came up with it?
-          When did they come up with it?
-          What evidence did they use to support their theory?
o   Be sure to include how plates move.
  1. Plate tectonics theory is the theory that the outer rigid layer of the earth (the lithosphere) is divided into a couple of plates that move around across the earth's surface. Alfred Wegener also came up with this theory around 1912.One of the first pieces of geophysical evidence that was used to support the movement of lithospheric plates came from paleomagnetism. This is based on the fact that rocks of different ages show a variable magnetic field direction, evidenced by studies since the mid–nineteenth century.
4)     The theory of Hot Spots
-          Who came up with the theory?
-          When?
-          What evidence did they use to support their theory?
-          Is the theory accepted?
In 1963, Canadian geophysicist J. Tuzo Wilson came up with the hotspot  theory to explain why although most earthquake and volcanic activity happened at plate boundaries.Wilson noted that in certain locations around the world, such as Hawaii, volcanism has been active for very long periods of time.He reasoned that if relatively long lasting and exceptionally hot regions called hotspots existed below the plates it would provide localized sources of high heat energy to sustain volcanism. It was accepted by some people however rejected by others. Some people could not fit this theory with the plate tectonics theory and thought the scientist was WRONG.




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