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1596 Abraham Ortelius (a mapmaker) stated that the coast lines of the continents appeared to fit together.
He used this observation to state that the continents were once joined and that the Americas were once
joined to Europe and Africa.
1785 Catastrophism (shape of the Earth was defined by the biblical flood) remained a fact until James Hutton
put forward his belief that "the present is the key to the past". This was the Uniformitarian Principle.
1855 US Navy lieutenant Matthew Maury published a bathymetric chart where he revealed the evidence of
underwater mountains in central Atlantic. The acceptance that oceans were flat was changing. He called
the central Atlantic mountains "Middle Ground". This is now known as Mid-Atlantic Ridge.
1912 A German meteorologist and geophysicist known as Alfred Wegener proposed that the continents were
once joined in a supercontinent called Pangaea.
He believed that Pangaea's constituent portions moved thousands of miles apart of a long period of
geologic time this is what is known as continental drift theory.
1920s Scientists Kiyoo Wadati & Hugo Benioff had identified zones extending several hundreds of kms across
Earth and inclined 40 to 60 degrees from the horizontal. These are called Wadati-Benioff zones; scientists
were able to identify these zones as earthquake areas as well.
1929 British geologist Arthur Holmes then proposed that convection in the mantle is the force driving
continental drift. His ideas were not taken seriously at the time however it later gained support.
1947 Scientists were intrigued by the fact that the present ocean floor was thinner than they expected.
The History Of Plate Tectonics
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Ewing noted that the rocks present in the islands of the Atlantic were volcanic and of recent age. He also
noted that the central Atlantic underwater mountains extended all along the centre of the Atlantic
forming a continuous mountain range from North to South Hemisphere.
1950 Magnetometers (used in WWII for detecting German submarines) were converted for use in deep oceanic
exploration. A global mid-ocean mountain ridge was confirmed and the term "Middle Ground" became
"Mid-Atlantic Ridge".…read more
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The WWSN (Worldwide Standardized Seismograph
Network) main use was to monitor the compliance of this treaty.
Mid-1960s A global network of sensors were installed they detect hydro acoustic signals and also recorded
earthquake and activity.
Scientists used this to find that earthquakes and volcanic activity occur at the edges of tectonic plates.
1968 A vessel set sail called Glomar Challenger to explore the mid-ocean ridge between South America and