Seafloor Spreading

Seafloor spreading is the theory that new oceanic crust is continuously created at mid-ocean ridges, where molten material rises from the mantle, and then moves outward on either side of the ridge as tectonic plates diverge. American geologist Harry Hess proposed the theory in a widely circulated 1960 manuscript, formally published in 1962 as History of Ocean Basins, describing the ocean floor as behaving like a slow conveyor belt. Strong confirming evidence came in 1963, when Fred Vine and Drummond Matthews, building on an idea also reached independently by Lawrence Morley, showed that magnetic striping patterns recorded symmetrically in the rock on either side of mid-ocean ridges matched the known history of Earth's periodic magnetic field reversals. Seafloor spreading became one of the central pillars supporting the broader theory of plate tectonics, providing the mechanism by which oceanic plates are created and, eventually, consumed at subduction zones.