Seafloor spreading
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Seafloor spreading, or seafloor spread, is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.
Spreading at a mid-ocean ridge
Plate tectonics
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Plate tectonics is the scientific theory that Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concep
Seafloor spreading
…Hess from Princeton University and Robert Dietz of the U.S. Naval Electronics Laboratory in San Diego in the 1960s. The phenomenon is known today as plate tectonics. In locations where two plates move apart, at mid-ocean ridges, new seafloor is continually formed during seafloor spreading. Seafloor spreading helps…
Plate motion based on Global Positioning System (GPS) satellite data from NASA JPL Archived 2011-07-21 at the Wayback Machine. Each red dot is a measuring point and vectors show direction and magnitude of motion.
Alfred Wegener in Greenland in the winter of 1912–13