Australian Dictionary of Biography

David Evan Thomas (1902-1978), geologist, was born on 4 August 1902 at Ammanford, Carmarthenshire, Wales, third son of Thomas Thomas, railway signalman, and his wife Margaret, née Roderick. David attended the Amman Valley County School and the University College of Wales, Aberystwyth (B.Sc. Hons, University of Wales, 1924). His education had been facilitated by scholarships during his secondary schooling, by part-time employment as a coalminer in his university years, and by a Rudler exhibition in geology at Aberystwyth in 1924. After graduating, he worked as an underground surveyor at the Blaenau colliery. This experience engendered a love of geological surveying, structural geology and graptolite biostratigraphy, and reinforced his predilection for precision.

In 1925 Thomas migrated to Australia. A seamen's strike compelled him to travel the last leg of his journey by train from Fremantle to Melbourne. Joining the Victorian Education Department in November, he taught in schools at Kennedys Creek and Nhill, but clashed with a district inspector over teaching methods and transferred to the Department of Mines in April 1927 as an assistant field geologist. He undertook surveys in the Western District, Gippsland and central Victoria. On 20 October 1932 at Lancefield he married with Catholic rites Mary Scanlon (d.1977); two of their three sons died in infancy. In 1939-42 Thomas was head of the department's office at Castlemaine. With Alexander Keble and later William Harris, he surveyed the geological structure of central Victoria, making particular use of graptolite biostratigraphy. For this work the University of Melbourne awarded him a D.Sc. (1940).

Appointed government geologist of Tasmania in February 1942, Thomas undertook research on graptolites, dendroids and hydroids, interspersed with investigations of strategic minerals required during wartime. In February 1944 he returned to Victoria and took a post with the State Rivers and Water Supply Commission. His meticulous geological mapping for the enlargement of the Eildon Reservoir brought him into daily contact with engineers. Thomas's monograph, Geology of the Eildon Dam Project (1947), stamped him as arguably the best structural geologist in Australia.

In May 1945 Thomas rejoined the Department of Mines and in February 1946 became Victoria's chief government geologist (director of geological survey from 1960). Field geology continued to be his passion, despite the administrative chores that governed much of his time, and he often devoted his weekends to field-work with his young geologists. Overcoming the resistance of a succession of cabinet ministers and departmental secretaries, he managed to increase the number of geologists on his staff from three to twenty. They benefited from his leadership and relentless efforts on their behalf. He encouraged them to carry out both detailed and broad-based research, insisted that they publish their results and persuaded the government to allow them to undertake doctoral studies. Three of his major initiatives were to create an energetic groundwater group, to develop engineering geology, and to foster biostratigraphy as a means of obtaining fine-scale correlations of the times of deposit of rock sequences to illuminate regional geological relationships.

Thomas published voluminously on the geology of Victoria and, to a lesser extent, Tasmania. He produced over one hundred scientific papers, fourteen geological maps, and more than 120 unpublished reports on almost all aspects of the earth sciences. His papers encompassed economic geology, structural and stratigraphic studies, graptolite and hydroid investigations, and regional geology. He had an admirable command of earth-science literature in French and German, and a commendable ability to embrace new ideas.

On regular trout-fishing expeditions in eastern Victoria, Thomas and Harris made observations of rock formations and collected graptolites. Their work led to radical re-interpretations of the geological structure of the State. Thomas achieved international recognition for his research on graptolites, work that had been largely done as a hobby. Thomas and Harris used Victoria's graptolite faunas to elaborate the scheme for dividing the sedimentary rock sequences of the Ordovician period into a succession of biostraphic zones. In 1963 Thomas was elected a fellow of the Australian Academy of Science.

Thomas was a councillor and life member of the Royal Society of Victoria. He served on the State committee of the Council for Scientific and Industrial Research (Commonwealth Scientific and Industrial Research Organization) and many other scientific and governmental bodies. On leave in 1963-64, he led a United Nations team to investigate the underground water and mineral resources of Cyprus, but civil war crippled the project. After his formal retirement in 1967, he was an honorary geological consultant to the department for several years.

As a boy, Thomas had an excellent soprano voice. He played the piano and enjoyed classical music, especially opera and choral singing. At the Amman Valley County School he had captained the Rugby Union football and cricket teams; at Aberystwyth he gained a Blue for boxing. In Australia he took up golf and earned a low handicap. He continued to play cricket, prided himself on his accuracy as a spin bowler, and had an encyclopaedic knowledge of the game. It was his custom to hold court in the Windsor Hotel, Spring Street, Melbourne, where—in conversations liberal with anecdote, wry humour and gentle repartee—he acquainted many of the geological fraternity with recondite and at times bizarre aspects of the scientific and commercial worlds, with the taxonomy and biostratigraphy of his beloved graptolites, and with the technical minutiae and history of various sports.

Thomas had a commanding presence that some initially found intimidating and that belied his graciousness, affability, loyalty and unswerving intellectual honesty. Survived by his son, he died on 27 November 1978 at Camberwell and was buried in Templestowe cemetery. The Victorian division of the Geological Society of Australia instituted the D. E. Thomas medal which is awarded to university students who excel in field-work.