Sea floor spreading theory
Theories that explains various Earth's movement -
Sea floor spreading theory - The mapping of oceanic floor revealed the following observations -
- Presence of mid-oceanic ridges along the sea floor.
- The ridges are very active with continuous volcanic eruption.
- The rocks of similar composition and magnetic properties and age are observed at equidistant location from the mid-oceanic ridges.
- The age of rocks increases away from the mid-oceanic ridges.
- The age of oceanic crust is much lower than that of continental crust.
- Thickness of oceanic crust is much lower than continental crust.
Based on the above observations, Harry Hess in 1961 proposed the theory of sea-floor spreading.
According to it, the constant magmatic eruption at the oceanic ridges causing the rupture at the oceanic crust releases lava which wedges onto oceanic crust on both the sides. This pushes the oceanic crust on either side of the ridges. Therefore the oceanic floor is spreading.
The spreading crust sinks down at the oceanic trenches and get consumed.
Speed at which ocean floor is spreading - 6-15 cm/year
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Note - This is my Vision IAS Notes (Vision IAS Class Notes) and Ashutosh Pandey Sir's Public Administration Class notes. I've also added some of the information on my own.
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