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Dr Martin Dodson

Dr Martin Dodson

Dr Martin Dodson, one of the pioneers in the quantitative measurement of the ages of rocks by isotopic methods in the 20th Century, died on 27th June 2010.

Born in 1932 and a pupil at Bootham School, York, from 1947-1950, Martin went up to St Johns College, Cambridge, in 1950 to read for the Natural Sciences Tripos. His main subject was physics but, significantly for his future career, his degree programme also included geology as a subsidiary. Following a period of research at Cambridge after graduation, Martin joined the UK Atomic Energy Authority as a Scientific Officer in 1956, working on the diffusion and flow of gases in porous solids. However, he soon returned to the academic fold, becoming a Research Fellow in the Department of Geology and Mineralogy at Oxford University in 1958, where he was a member of the geochronology group. Geochronology, the science of determining the age of rocks and minerals, was still in its comparative infancy as a discipline and Martin was to be one of the scientists instrumental in its rapid evolution. Indeed, one of his first tasks, in the absence of a suitable commercially available instrument, was to build a gas mass spectrometer. Whilst at Oxford, Martin completed his DPhil, which he was awarded in 1963. In the same year, he was awarded a post-doctoral fellowship by the National Research Council of Canada, which he took up at the University of Alberta.

Martin returned to the United Kingdom in 1964, on his appointment to Leeds as Lecturer in Geochronology and Isotope Geology, where he remained until his retirement in September 1992. Here he set up a new geochronology laboratory in the Earth Sciences department, created on the initiative of Professors W.Q. Kennedy and R.M. Shackleton. One of only four such laboratories in the UK a reflection of the technically exacting nature of the work, as well as of the high cost of the facilities the Leeds laboratory became internationally recognised for the high quality of its fundamental research at the frontiers of a fast-developing subject. To a large extent, this acclaim derived from the work of Martin himself.

During the 1960s and early 1970s the Department and the Institute of African Geology, which it housed, had a particular focus on African geology. Consequently, much of the early work in the geochronology laboratory concerned the age of the Earths crust in various parts of Africa. The subjects of Martins dating studies ranged widely across southern and eastern Africa and he maintained an interest in this area throughout his career, well into retirement; one of his most recent papers, in 2001, concerned a 3400 million year old granite, one of the oldest rocks in Africa.

Martin was a man of considerable intellectual stature and ability and his research reflected his wide interests in both physics and Earth Science. He published some 45 papers between 1961 and 2006, eight of which were published in the journal Nature. From the late 1960s it had become apparent that many age measurements did not record the age of formation of the rock sample, but some later stage in its geological history. It was in this area of research that Martins insights from theoretical physics became most strongly apparent, leading to his greatest scientific contribution to the field of geochronology. He developed a quantitative physical model, based on thermal diffusion, which related the measured age to a specific stage in the cooling of the rock from higher temperatures. This model went on to underpin the developing science of thermochronology and his 1973 paper, published in Contributions to Mineralogy & Petrology, continues to be regularly cited to this day (1200 citations, 50 citations in 2009 alone). Further development of the model in subsequent years led to quantitative modelling of variations in isotopic concentrations within samples that result from losses by diffusion and, in collaboration with Elizabeth (Buffy) McClelland, he extended these ideas into the field of palaeomagnetism. Recognition of the magnitude of his contribution to the field of thermochronology was shown by an invitation to be a guest at an international conference Thermochronology 2010 in Glasgow this August. Sadly his death preceded this event.

Martin also made several fundamental technical contributions to the measurement of isotopic compositions, including the first systematic studies of error relationships in isotope dilution analysis and in particular the use of double spiking to achieve greater precision and accuracy. He was also responsible for recognising the potential of diffusively enriched Ar38 in the early days of potassium-argon dating.

Always conscious of his training as a physicist rather than a geologist, Martin nevertheless made great strides in understanding the geologists approach, although ultimately it was his physicists concern to reduce problems to manageable simplicity that was his greatest strength. He contributed enthusiastically to teaching elementary geology in the laboratory and in the field. For many years he was Admissions Tutor, coordinating the departments selection of undergraduate students. He was as adept at providing remedial tutorials in mathematics and physics for undergraduates as he was in training research students and scientific workers from other institutions in the very exacting procedures demanded by geochronological research.

Outside the Earth Sciences Martin made another significant contribution to University life. He was a fine and sensitive musician who particularly enjoyed accompanying student musicians on the piano for their practical examinations. His considerable prowess as a pianist delighted University audiences on a number of occasions. In retirement he continued to be very active as a musician.

Among the many messages of condolence from colleagues across the world it is notable how many commended, in addition to his scientific achievements, his great warmth, gentle demeanour and concern for the well-being of others. He was much liked and respected and will be greatly missed by all who knew him.

Martin is survived by his wife, Hilary and children Nick, Isabel and Joe.

Published: 7 July 2010