a three-year spell in the merchant marine, a job that gave him ample time for pursuing his love of eclectic reading.
Chemistry remained his chosen field when he returned to Berkeley, but a summer job in Alaska with Clyde Wahrhaftig convinced him that geology was more to his liking. Continued work in chemistry proved so dull that his grades suffered, and as a result he lost his draft deferment. Two years in the Army made a return to school seem especially attractive, again at Berkeley but this time with a major in geology. More trips to Alaska with Wahrhaftig elicited an interest in glaciers, both ice glaciers and rock glaciers, and particularly in the mechanics of glacier movement. He had fond memories of those expeditions, not only for their scientific content but also for long conversations on the works of Proust and the music of Bach.
In graduate work at Berkeley Allan came under the influence of John Verhoogen and chose geophysics rather than glaciology for his specialty. Verhoogen at the time was much interested in rock magnetism, and this was the subject that became the focus of Allan's doctoral research. Verhoogen also was one of the very few at Berkeley who thought there might be some validity in the idea of continental drift.
This was an hypothesis proposed in 1912 by a German meteorologist, Alfred Lothar Wegener, suggesting that the continents are not fixed in their present positions on the Earth's surface, but over geologic time have drifted widely, joining together, breaking up, and assuming new shapes. Continental drift plays a major role, of course, in the current doctrine of plate tectonics, but in the 1950s it was generally regarded by geologists, in the northern hemisphere at least, as a wild notion with little evidence to back it up. Verhoogen's solitary support of the hypothesis made a deep impression on Allan, and he came to regard continental drift as a real possibility. In his Arthur Day Lecture many