Sea Floor Spreading

Q.Write short note on seafloor spreading theory (08/20)

Concept of seafloor spreading was given by Harry Hess in his work titled ‘Essays in Geo-poetry’ published in 1960s.

He connected his findings related to mid-atlantic ridge(using sonar technology) and convectional current theory to arrive at his theory of seafloor spreading which talks about horizontal movement of ocean floor.

CONVEYOR BELT MECHANISM

Rising limb of conventional current lies below the continental ridges.This rising plumes spreads below the ridge providing tensional stress and a driving force for the parallel movement of ocean floor away from the ridge.Some of these rising magma comes out of the ridge and spreads itself on the both side of ridge.This results in creation of fresh layer of ocean floor. Thus, ocean floor is being created at the oceanic ridge such that the younger layer lies near ridge and older away from it.Thus, oceanic basin was estimated to be not older than 200 millions years.

At the same time, oceanic basins are destroying itself near subduction zone where the subducted part of oceanic floor are being melted and turning into magma, Thus, seafloor spreading forms a part of a conveyor belt system containing ridges,ocean floor,subduction zone while the conventional system of magma playing the role of the engine powering whole movement.

VINE-MATTHEWS-MORLEY HYPOTHESIS

These scholars connected seafloor spreading with existence of symmetric pattern of geomagnetic reversal in ocean crust.This was later proved and formed the basis of plate tectonics theory.