John Tuzo Wilson developed crucial concepts that related to plate tectonics in 1963.
He asserted that the Hawaiian, and other island chains, may have formed due to movement of a plate over a "hot spot" in the Earth's mantle.
[Note: A __Hotspot___ is an area of abnormally intense active volcanism.]
He also argued that there must be a third type of plate boundary to connect ridges and trenches- which are called transform faults. These allowed for plates to slide past one another without oceanic crust being created or destroyed.