Plate tectonics is a theory that Alfred Wegner came up with in 1915. The theoy explained the strange puzzle-like fit between some of the coastlines of the continents. He proposed that the Earth was made up of several large plates that actually float on the lithosphere. Convection currents are believed to be the driving force behind these movements. Plates’ boundaries are is where there is high seismic activity, such as volcanoes, earthquakes, and mountain formation.