David Evan Thomas is distinguished for his researches on the geological structure of Victoria, to which he has made many major contributions. He is a foremost world authority on the fossil group of the graptolites. His studies of Victorian gold occurrences have great significance not only for economic and structural geology for also for theories of the migration of fluids through rocks. He has added greatly to the knowledge of Victorian lignite deposits and underground water occurrences. He has consistently given every support to, the members of his staff in the prosecution of original fundamental research.