In today’s Google Earth world, it’s hard to remember that until recently much of the planet remained a literal blank on the map. Ocean floors, in particular, were a greater mystery than the surface of the moon.
Not until the 1950s did the face of the deep begin to reveal itself, thanks to painstaking cartography by Marie Tharp and Bruce Heezen of the Lamont Geological Observatory. Line by line, Tharp transformed sound waves bounced off the ocean bottom into 3-D maps. With them, and with Tharp’s discovery of a rift running down the Atlantic’s middle, scientists finally visualized plate tectonics and developed their modern understanding of the Earth.