Gill, William Daniel (1916–92), geologist, was born 29 June 1916 at Hillam, Yorks., second child among three sons and three daughters of Richard Wells Gill, farmer, and Eva Gill (née Hesselgrave). He was educated at Castleford Grammar School and Leeds University, where he had a successful undergraduate career and received a degree in geology (1938). Robert George Spencer Hudson was his professor, and the two men remained close friends for the next thirty years.
On leaving Leeds he joined the Attock Oil Company (1938) as a field geologist and palaeontologist. During the second world war he worked as a development geologist and petroleum engineer in India (including the Punjab, later part of Pakistan) and Burma, and became a leading expert on Himalayan geology. In 1948 he left the oil industry for academia and a lectureship in geology at Nottingham University. Two years later he was awarded a D.Sc. (1950) by Leeds University for his publications on Himalayan geology, and in 1953 he was appointed professor of geology and mineralogy at TCD, the first non-Irish holder of the position since 1883. Under his direction and with the aid of funds from the earl of Iveagh (qv) and oil industry contacts, the geology department experienced a period of expansion. A vibrant postgraduate school of research was initiated, which led eventually to an increase in staff numbers. The museum building, which housed the department, was internally reconstructed to include new research and teaching facilities. Unfortunately many of the original museum's historic rock collections were discarded in the move.
In Ireland his research interests focused on the Upper Carboniferous rocks of Co. Clare, and particularly on the deformation features of soft sedimentary structures so clearly exposed there. He published a significant paper on sand volcanoes with P. H. Keunen (1958) and brought his Clare work together in a later publication of the Geological Survey of Ireland (1979). He was in his element in the field, where his enthusiasm for his subject was said to be more eloquent than in the lecture theatre. As oil and mineral exploration was initiated in Ireland in the 1950s, he took on the role of consultant, and, with his students, was involved in regional geological mapping. He expanded his consultancy role to oil companies in Libya and Greece and in 1961 resigned from Trinity to accept the chair of oil technology at the Royal School of Mines, Imperial College, London, later becoming professor of petroleum geology (1976). Hudson, his original professor, replaced him at TCD (1961–6) in the chair of geology.
In London Gill introduced the M.Sc. course in petroleum geology and established the first UK-based organic geochemistry laboratory for the study of petroleum-source rocks (1969). He continued to consult with oil companies and governments in Europe, the Middle East, Africa, Australia, and Canada. His extraordinary memory and ability to assimilate and synthesise information and data led to successful oil finds in newly explored areas. As a geologist he was most interested in the concepts of large-scale tectonic processes in such places as the Alps, the Himalayas, and the east African rift. However, his impatience with detail meant his publication record never quite kept pace with his achievements. During his career he was elected FTCD (1958), fellow of the Geological Society of London and of the Institute of Petroleum (London), MRIA (1955), and member of the RDS (vice-president 1959, 1961).
A self-confident and flamboyant man with a large physical presence, he is said to have had grandiose plans which did not always come to pass. Known as ‘Dan’, he was popular with both students and staff and was viewed as warm-hearted and straightforward. University politics, however, were not his strong point. On the death of Hudson (1966), Gill professed an interest in returning to Trinity, provided he did not have to submit a formal application form. However, TCD did not respond.
He married (1946) in India Margaret ‘Betty’ Torrance, whom he had met in the Yorkshire dales when he was mapping as a student; they had two daughters. Their houses (16 Garville Avenue, Rathgar, Dublin, and 85 Platt's Lane, Hampstead, London) were the frequent hub of late-night parties, where Dan would sing and play the piano. An active sportsman, he loved cricket and was president of the Trinity boat and rugby clubs. In 1978 he retired to Glusburn Green, Glusburn, Yorks., but continued consultancy work in the Middle East for some time afterwards. His wife died in 1987; five years later, he died (29 October 1992) in Yorkshire.