The idea came primarily from Harry Hess, one of the founding fathers of the theory of plate tectonics, and Walter Munk, who pioneered studies of how winds drive ocean currents and explained why one side of the Moon is locked towards Earth. (The hole itself is not the deepest ever drilled into the sea floor; that was Hole 504B, which reached 2,111 metres below the bottom of the eastern Pacific off Colombia.) The mission should help to settle many debates: how crust is formed at mid-ocean ridges; how magma from the mantle is intruded into the lower crust; the geometry and vigour of how sea water can pull heat from the lower oceanic crust; and the contribution of the lower crust to marine magnetic anomalies.