John Sclater is well known for his work on the evolution of ocean basins. He convincingly demonstrated that the age of the sea floor controls its depth, and then used this empirical relationship to investigate the thermal structure of plates, to work out the evolution of the Central Eastern Pacific where magnetic anomalies could not be recognised and to produce paleobathymetric maps. This use of plate tectonics to understand oceanic bathymetry is one of his major successes. His other major contribution concerns the complicated evolution of the Indian Ocean. This work produced an evolutionary framework from magnetic anomalies which he among others confirmed by drilling, and later lead to new ideas about the evolution of aseismic ridges. He also made important contributions to understanding the evolution of margin basins, and the hydrothermal circulation in the oceanic crust.