Stephen and his twin brother were born in Croydon and moved to Montreal in 1940; he returned to Britain to join the Royal Navy in 1943 and was commissioned a Sub-Lieutenant RNVR in 1944. In 1946 he entered the Geology Department, University College London and under the influence of Prof. Hollingworth became a dedicated exploration geologist. In 1949 he married Vivien Mills, also a departmental graduate, who shared that interest.
He joined the Geological Survey of the Nyasaland Protectorate in 1950 and spent seven years surveying the Shire Highlands and Middle Shire rift valley, identifying a transition zone between amphibolite and granulite facies gneisses, as well as several large syenite plutons. Between 1955 and 1990 he published five papers on these rocks and the work on the Middle Shire and Ncheu areas formed the subject of his London PhD, awarded in 1960.
Transferring in 1957 to the Cyprus Geological Survey, Stephen joined a team mapping the Troodos ophiolite complex and surrounding sediments. His area to the east of the complex included the Pitsillia, Limassol Forest and country south to Akrotiri. British geologists left the Survey when Cyprus became a Republic in 1959, but the team's work was incorporated in Memoir 7 of the Survey.
He was then appointed a Lecturer in geology at the Sir John Cass College, London before changing in 1962 to Senior Lecturer at the Northern Polytechnic where he established a successful department. In a major role change in 1968, he became principal economic geologist to the Botswana Geological Survey and investigated the mineral resources of the Tati goldfield. That role expanded in 1969 when he joined INCO as exploration manager for Africa and, jointly with the Anglo-American Corporation, identified 10.5 million tons of nickel-copper sulphide ore, grading 1.7 Ni equivalent, in the Tati Concession. He also led geological and geochemical surveys for sulphides in the Messina-Limpopo area of South Africa and in central Malawi.
In 1972 he accepted the new chair in geology at Fourah Bay College, University of Sierra Leone. He introduced degree level courses, including exploration geophysics and geochemistry, engineering geology and hydrogeology, but the appointment ended in 1977 when the University was sacked by a political mob. While researching a greenstone belt in 1976 he suffered a heart attack.
Joining Sir William Halcrow and Partners in 1977 he planned a groundwater development programme for Somalia but this was abandoned due to war with Ethiopia. Subsequently, as a private consultant he published on the mineral resources of Sierra Leone and undertook a mineral survey of western Thailand.
Under the auspices of a Dutch Government Agency, Stephen was appointed in 1981 as Professor of a new department in the University of Botswana. Following a second heart attack in the field in Malawi he underwent cardiac surgery in London before returning to Botswana until 1985. The Dutch Agency funded his continuing research into the geothermometry and geobarometry of the Malawian rocks at the Free University of Amsterdam.
Settling at Rye after retiring, he and his wife continued research in the Algarve and supported the Hastings Geological Society. The eldest of their four children, Hugh Morel, is a petroleum geologist.
David Gray