Who discovered tectonic plates?

Plate tectonics theory was developed in the 1960s, but was truly a collaborative effort among three different scientists over the course of 50 years. The idea began in 1912 with Alfred Wegener's theory of continental drift, which stated that the continents were originally one giant landmass that eventually split and moved apart. However, there was no evidence that continents could actually move. In 1920 Arthur Holmes suggested that continental plate junctions may actually exist under the sea, and then in 1928 he added that convection currents within the earth's mantle could provide the motion. The first actual evidence that continental plates could in fact move came with the discovery of variable magnetic field direction in rocks of different ages. Additional research by Harry Hess and Ron Mason having to do with seafloor spreading and magnetic field reversals further refined the theory of plate tectonics. Additional geological observations of magnetic forces on the ocean floor finally gave plate tectonics universal acceptance.