The document outlines a timeline of significant milestones in the understanding of plate tectonics from 1620 to the 1990s. Key figures such as Francis Bacon, Alfred Wegener, and Harry Hess contributed foundational ideas and evidence, including continental fit, fossil similarities, and sea floor spreading mechanisms. Advances in technology, including seismic tomography and GPS measurements, further enhanced the study of Earth's geological processes.

1. PLATETECTONIC
EVIDENCE
Praag Dogra

2. Timeline
■ 1620
■ 1820
■ 1913
■ 1945-1960
■ 1963 (x3)
■ 1964
■ 1970
■ 1990+

3. 1620 – Francis Bacon
■ Francis Bacon came up with the idea of a ‘Jig-saw’ fit of the continents.
■ He noted that the South American Continent fitted in with the African Continent.

4. 1820
■ Palaeontology geology was founded and suggested fossil similarities across
continents over the earth
■ Glossopteris, Lystrosaurs and Mesosaurus are among the most noted fossils found
over earths continents

5. 1913 – AlfredWegener
■ AlfredWegener suggested the theory of continental drift
■ He spotted rock similarities across oceans basins and mountain chains over the world
■ He found Paleoclimatic evidence of glacial metamorphic ground moraine (rock
deposits) likeTillite in Namibia and chalk in the UK
■ This evidence suggests that Namibia and the UK must have both been over the
equator over the last 200 million years

6. 1945-1960
■ TheWorlds scientists mapped the sea floors

7. 1963 (1) – Harry Hess
■ Harry Hess suggested that convection currents are responsible for the spreading of
the sea floor

8. 1963 (2) –Vine and Matthews
■ FredVine and Drummond Matthews found that there are Paleomagnetic stripes either
side of the Indian ocean ridge
■ It shows how Earths magnetic field reverses its polarities over time. As this occurs,
there are extrusions of magma (called hematite) which solidify pointing the magnetic
pole at their time of solidification.This causes a series of alternation north and south
facing parallel polarity stripes of rock wither side of the Indian mid ocean ridge.

9. 1963 – USA and USSR
■ During the cold war, the US and USSR placed over 100 seismometers across the
oceans to find out the impact of bomb testing and their sizes.
■ What was actually found was high proportions of earthquakes across destructive plate
boundaries.

10. 1964
■ This is the date of the GreatAlaskan earthquake.
■ This was the reason for finding subduction at destructive plate boundaries.

11. Early 1970’s
■ There was the invention of seismic tomography
■ This measured the P and S waves through the lithosphere

12. 1990’s +
■ This was when there was an increase in the use of GPS measurements for more
accurate readings.