Continental Drift Theory Flashcards
Who was Francis Bacon?
The man in 1620 who first noticed that South America and West Africa fitted together
Who was Alfred Wegner?
The man who in 1912 published a theory supporting Francis Bacon that the continents were once aligned and together in one super continent
What was the name given to the super continent that Wegner believed previously existed?
Pangea
What was the biological evidence that Wegner proposed?
He found Mesosaurus fossils in Africa and South America. The animal lived in the same place it’s just that the continents containing their fossils had drifted apart. If they had swim across, why didn’t they swim anywhere else?
What was Wegners geological evidence?
Rocks found in S.America and W.Brazil were almost identical in age and structure. This showed that they were once conjoined because in order for rocks to form they depend heavily upon local climatic conditions. Therefore as they are similar they must have been under the same climate in the same location joined together
What was Wegners fossils fuel evidence?
Coal had been found in Antarctica, a very cold place with little moisture. In order for Coal to form it needs warm moist conditions. Suggesting that the continent used to be closer to the equator as the coal couldn’t have possibly formed there
Why, in 1912, was Wegners theory ignored?
> He was unable to mathematically explain why the continents had moved (he suggested the moon). >Also there wasn’t as advanced technology to prove his theory. >Strong religious view at this time of which many believed God created the world > He suggested that they were moving at 250cm per year (way too fast) > Not a geologist so why believe him
Who was Arthur Holmes and in what year was he important to the theory of continental drift?
In 1932 he proposed that the earth’s plate’s were moved by convection currents within the underlying mantle
What and when did Tharp & Heezen carry out their investigation that contributed to the future discoveries of continental drift and plate tectonics theory?
In the 1950s and 1960s they used sonar to map the Atlantic ocean floor that lead to the discovery of the MAR that would become subject of major future scientific research
What and when did Harry Hess contribute to PTT and continental drift?
In 1962, from the knowledge and theories of Holmes and Tharp & Heezen he suggested that magma was constantly being ejected from the MAR due to the connection currents and thus creating new land that was the sea floor. He also suggested, to put down any idea of the earth getting bigger, that land which had been created many years before the newer land at the MAR was being destroyed at a boundary with another plate (Convergent boundary)
How often does the earths polarity change?
200,000-400,000 years
With the information that Hess and Ewing collected it suggested that the earth was getting larger, but what was happening to stop this?
The crust at the edges of the Pacific Ocean were being destroyed at the same rate of new crust being formed at MAR
What other evidence has been discovered recently to prove Continental Drift?
Coral Reefs have been found across the world that too require specific climatic conditions to form, they are now in strange places and therefore must have formed before they moved away
What and When did John Tuzo-Wilson contribute for the first time to PTT?
In 1963 he suggested that underneath the Hawaiian islands was an extremely hot plume of mantle that could exploit weaknesses in the earth’s crust to reach the surface and cool to form active volcanoes fed by the same plume. He suggested that as the plate moved in a NW direction there was a new place for the plume to exploit and this create a new volcano. This process was repeated over millions of years to create the Hawaiian Islands
What confirmed that the Pacific Plate was moving in a NW direction?
Ocean Trenches at the North Edge
