the theory of seafloor spreading was proposed in the 1960s.
the theory of seafloor spreading was proposed in the 1960s.
when was the theory of seafloor spreading proposed?
1960s
following the discovery of the worldwide extent of the mid-ocean ridge in the 1950s, geologists faced a new task: explaining how such an enormous geological structure could have formed. in the 1960s, geologists discovered and began to propose mechanisms for seafloor spreading. the discovery of mid-ocean ridges and the process of seafloor spreading allowed for wegner's theory to be expanded so that it included the movement of oceanic crust as well as the continents. plate tectonics was a suitable explanation for seafloor spreading, and the acceptance of plate tectonics by the majority of geologists resulted in a major paradigm shift in geological thinking.
mid-ocean ridge
seafloor spreading helps explain continental drift in the theory of plate tectonics. when oceanic plates diverge, tensional stress causes fractures to occur in the lithosphere. the motivating force for seafloor spreading ridges is tectonic plate pull rather than magma pressure, although there is typically significant magma activity at spreading ridges. at a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. hydrothermal vents are common at spreading centers. older rocks will be found farther away from the spreading zone while younger rocks will be found nearer to the spreading zone. additionally spreading rates determine if the ridge is fast, intermediate, or slow. as a general rule, fast ridges have spreading (opening) rates of more than 9 cm/year. intermediate ridges have a spreading rate of 5–9 cm/year while slow spreading ridges have a rate less than 5 cm/year.
seafloor spreading