Chapter 2



By coincidence, in the early 60s Tuzo WilsonTuzo WilsonTuzo Wilson (1908-1993) worked at Princeton and was the first to suggest that island chains such as Hawaii arose as plates moved across a hot spot in the mantle below. In the early 1960s, maps of the magnetic anomalies on the ocean floor showed symmetrical patterns at mid ocean ridges, cut by discontinuities. With simple paper models, starting from Vine and Matthews’ work, Wilson suggested that transform faults were not later faults affecting ridges, but rather essential parts of the ridge system. Lynn Sykes at Lamont showed that earthquake motions along the faults matched Wilson’s model, and that transform faults away from the ridges were inactive. and Harry HessHarry HessHarry Hess (1906-1969) began his career at Princeton in the 1930s, undertaking submarine gravity experiments with Vening Meinesz. After war service and promotion to an Admiral of the US Navy, he returned to Princeton and his interests in marine geology. His proposal of seafloor spreading and the conveyor belt carrying new ocean crust away from the mid-ocean ridges was influential. He had also worked on the gravity anomalies that became associated with subduction zones, encouraging him to consider mantle convection as a part of plate tectonics. were both on sabbatical at Cambridge and shared an office at Madingley Rise. Wilson had the detailed magnetic data from the Pacific North West. What he did not have was equally detailed bathymetry; the US Navy data was classified. Hess, a US Navy Admiral, had seen the classified data and could confirm the link between magnetic anomalies and seafloor structure.

IMAGE REFERENCE: Figure from: Wilson (1965) ‘Transform faults, oceanic ridges’ Science. 150(3695): 482-485.