John Smith Flett was born in Kirkwall, Orkney, on 26 June 1869. He was educated at Kirkwall Burgh School and at George Watson's College, Edinburgh. In 1886 he entered Edinburgh University studying Arts, Science, and Medicine, and was awarded the degree of M.A. at the age of nineteen, the degree of B.Sc. in 1892, and the degrees of M.B. and C.M. (Master in Surgery) in 1894. A brief spell in medical practice followed, before he joined the staff of the Geology Department of Edinburgh University as Assistant to Professor James Geikie (1839-1915), and then as a Lecturer in Petrology. Flett's earliest noteworthy research was his investigations into the stratigraphy of the Old Red Sandstone of Orkney and into the petrography of the alkaline dykes found in that formation. For this Orkney research he was awarded the degree of D.Sc. from Edinburgh University in 1900, and that year too he became Fellow of the Royal Society of Edinburgh. In 1901, Flett took up the post of Petrographer to the Geological Survey of Great Britain, and acquired a comprehensive knowledge of British rocks. Whilst in post, he collaborated with Dr. Tempest Anderson (1846-1913) in studying the vulcanicity of the Soufriere and Mont Pelee in the West Indies. In 1911 he became Assistant to the Director of the Geological Survey of Scotland, and during the First World War he was responsible for the supply of geological information required. In 1918, Flett was appointed OBE and was awarded the KBE in 1925. Towards the end of his career, Flett was responsible for the transfer of the Geological Survey to the Geological Museum at South Kensington, in 1935. His published works include a collaborative piece,James Geikie: the man and the geologist(1917) as well asThe first hundred years of the Geological Survey of Great Britain, 1835-1935(1937). Sir John Smith Flett died at Ashdon, in Essex, on 26 January 1947.