One of the most important geoscientists of the twentieth century, Arthur Holmes was born in Gateshead, in industrial northeast England. He won a scholarship to study physics at the Royal College of Science in London, but soon switched to geology. He graduated in 1910. In 1913, before even earning his doctoral degree, Holmes proposed the first geological time scale in his book The Age of the Earth, based on the fairly recently discovered phenomenon of radioactivity. Holmes made an estimate of Earth's age that was far older than anyone had suggested until then—4 billion years. It was not a popular theory at the time, but it established Holmes, at the age of 23, as a world authority on the subject.
Despite much personal hardship and struggle in his early years—and many necessary diversions from his scientific work—Holmes made another significant contribution to geology. Years before the scientific community accepted Alfred Wegener's theory of continental drift, Holmes hypothesized (correctly) how it could have happened—through slow-moving convection currents in the Earth's mantle which, he suggested, could force the continents toward or away from one another, creating new ocean floors and building mountain ranges. He would live just long enough to see the dawn of plate tectonics.
Holmes served as professor of geology at the University of Durham for 19 years, and continued in that same capacity at the University of Edinburgh until his death in 1965. In addition to the Vetlesen Prize, Holmes was twice honored in 1956, with the Wollaston and Penrose Medals.