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Question:  Briefly explain sea floor spreading theory. Provide evidences that strengthen the theory.


Answer:  Sea floor spreading theory was proposed by Harry Hess to explain formation of formation of oceanic crust and continent crust. The theory also gives the reason for separation between continents that we observe today.

  • The theory says that both the continental crust and oceanic crust originated from the same source due to rapid cooling of interior magma.
  • This Magma was shifted out of its location to form new land and ocean crusts. This explained the occurrence of same rocks everywhere on Earth.

Evidences of sea floor spreading theory

  • Origin and composition of rocks
    The rocks obtained on land were having similar characteristics to that of oceanic rocks. The composition of rocks contain various minerals and deposits that are of oceanic origin. This gives evidence of the way the rocks were formed.
  • Mid oceanic ridges
    Mid oceanic ridges discovered under sea provides evidence of Magma activity that resulted in formation of rocks. The rock cycle provides the indication of rock recycling. The width of ridges vary continuously indicating an intense activity.
  • Wagner’s theory
    Wegner proposed continental drift theory that gave evidence of how continental mass separated. The force or event that resulted in continental drift was explained by sea floor spreading. Thus, both theories filled the missing pieces of the puzzle.
  • Modern study
    Latest studies have indicated that continents are moving away from each other. The rock samples collected from deep oceans are younger in nature. This shows that new crust is continuously formed and old ones destroyed. The age of rocks of continents are older than that of ocean.
Updated on 01 Dec 2020 |   Added on .02 Nov 2020  |  by admin