Arthur Holmes

Arthur Holmes was an English geologist widely credited as a founder of modern geochronology, the science of dating rocks and geological events. As an undergraduate, Holmes carried out one of the first accurate uses of radiometric dating on minerals, publishing results in 1911 that used the decay of uranium into lead to estimate the ages of rock samples far more precisely than earlier methods allowed. Over his career Holmes progressively refined his estimate of Earth's age using this radiometric approach, moving from around 1,600 million years for certain ancient rocks in 1913 to approximately 4,500 million years by the 1940s, in a body of work that became known as the Holmes-Houterman model of Earth's age. Holmes was also an early and influential supporter of Alfred Wegener's theory of continental drift at a time when most geologists rejected it, proposing in the 1930s and 1940s that slow convection currents within Earth's mantle, driven by radioactive heat, could provide the physical mechanism moving the continents, an idea that anticipated the later theory of plate tectonics. Holmes led the geology department at Durham University from 1924 to 1943 and held the chair of geology at the University of Edinburgh from 1943 to 1956.