A WWII submarine detector helped map seafloor magnetic stripes and prove plates move

A device built to track enemy submarines during the Second World War went on to become one of the most important tools in Earth science. The fluxgate magnetometer, first developed to detect small disturbances in the planet's magnetic field caused by metal hulls beneath the ocean surface, was later adapted by scientists to study the seafloor itself. According to Science News, the device's origins trace back to 1936, when researchers designed a highly sensitive magnetic sensor, which was then made portable for aerial use during the war under the guidance of geomagnetist Victor Vacquier.Once the fighting ended, oceanographers repurposed the same technology for peacetime research, towing it behind survey ships to map magnetic patterns hidden in seafloor rock. What they found reshaped scientific understanding of how continents move. The patterns recorded by the fluxgate magnetometer would go on to provide some of the clearest physical evidence yet gathered for the theory of plate tectonics, an idea that had been widely dismissed by geologists only a few decades earlier.How the fluxgate magnetometer detected submarines during World War IIThe fluxgate magnetometer worked by using an iron ...