The Seafloor Spreading Hypothesis

Seafloor spreading as upwelling of magma continues the plates continue to diverge a process known as seafloor spreading.

The seafloor spreading hypothesis. Seafloor spreading theory of lithospheric evolution that holds that the ocean floors are spreading outward from vast underwater ridges. When oceanic plates diverge tensional stress causes fractures to occur in the lithosphere. In this hypothesis hot buoyant mantle rises up a mid ocean ridge causing the ridge to rise upward figurebelow. Seafloor spreading and other tectonic activity processes are the result of mantle convection.

Hess its major tenets gave great support to the theory of continental drift continental drift. Seafloor spreading theory that oceanic crust forms along submarine mountain zones known collectively as the mid ocean ridge system and spreads out laterally away from them. Mantle convection is the slow churn ing motion of earth s mantle. Seafloor spreading helps explain continental drift in the theory of plate tectonics.

Tuzo said that earth s crust or lithosphere was divided into large rigid pieces called plates. In 1962 these ideas. First proposed in the early 1960s by the american geologist harry h. Harry hess s hypothesis about seafloor spreading had collected several pieces of evidence to support the theory.

A mystery solved in 1912 when alfred wegener proposed that the continents had once been joined together and had split apart the biggest weakness in his hypothesis was the lack. This evidence was from the investigations of the molten material seafloor drilling radiometric age dating and fossil ages and the magnetic stripes. This idea played a pivotal role in the development of the theory of plate tectonics which revolutionized geologic thought during the last quarter of the 20th century. Hess like wegener ran into resistance because little ocean floor data existed for testing his ideas.

The motivating force for seafloor spreading ridges is tectonic plate slab pull at subduction zones rather than magma pressure although there is typically significant magma activity at spreading ridges. In 1959 he informally presented this hypothesis in a manuscript that was widely circulated. These plates float atop an underlying rock layer called the asthenosphere. Magma at the mid ocean ridge creates new seafloor.

This evidence however was also used to support the theory of continental drift. Resulted in a ground breaking hypothesis that later would be called seafloor spreading. Tuzo wilson combined the continental drift and seafloor spreading hypotheses to propose the theory of plate tectonics. Samples collected from the ocean floor show that the age of oceanic crust increases with distance from the spreading centre important evidence in favour of this process.