Obituary: Drummond Matthews

Plate tectonics is now in the National Curriculum, so practically every schoolchild knows that Britain is drifting away from North America at about the rate your fingernails grow: roughly six feet in a lifetime of three score years and ten. Yet in the early 1960s such ideas sounded preposterous. Geologists were familiar with the notion that the Earth's crust goes up and down, leaving, for example, sediments originally laid down underwater now at the top of the highest Welsh mountain, Mount Snowdon. But rapid horizontal movements sounded outrageous.

Drummond Matthews was one of the chief architects of the plate tectonics revolution which changed all that. Together with his then graduate student Fred Vine (now Dean of Science at the University of East Anglia), he recognised that the amazingly regular stripes of magnetised volcanic rocks on the ocean floor were created by the sea-floor's spreading apart, at rates of typically a few inches per year, along massive rifts running down the centres of the ocean basins.

This was the cornerstone of the plate tectonic theory. Although the ocean basins cover 70 per cent of the Earth's surface, they are continually being destroyed and created as the tectonic plates drift across the globe. It is a theory which has revolutionised not only the way we look at the Earth, but which now underpins major social and economic activities world- wide, including earthquake and volcanic risk assessment and oil exploration.

Matthews's research career started in 1958-61 with a PhD on rocks dredged from the North Atlantic. Before that he had done his obligatory National Service in the Royal Navy, and had taken a degree in Geology and Petrology at Cambridge in 1955. His degree results had been disappointing, so before returning to Cambridge in 1958 he had spent two years as a geologist in the Antarctic with the Falkland Islands Dependencies Survey (now the British Antarctic Survey). He attributed his subsequent diabetes, with the consequent deteriorating heart condition that accompanied a lifetime's use of insulin, to the huge quantities of butter that were supplied as Antarctic sledging rations; in practice they did little sledging but had nothing else to eat.

His discovery of sea-floor spreading stripes came from work in the Gulf of Aden during cruises on HMS Owen as part of the International Indian Ocean Expedition of 1961-63. Working alone, he not only ensured that the instrumentation was running 24 hours per day, but had himself to deploy and haul in by hand the 500- metre towed magnetometer cable. This epic, but careful observational work paid off. No one could have predicted what he found, yet it changed the way we view the Earth.

Following the untimely death of his mentor, Maurice Hill, in 1966 Matthews took over running the Cambridge marine geophysics group. This was a time he once called "the heroic period of ocean exploration": and heroic it certainly was. In the five years from 1967 to 1972, the members of the 15-strong marine group took part in 33 seagoing expeditions. Almost every cruise was to virgin territory and discovered new features of the ocean floor and its plate boundaries. Much of the specialist equipment they used was not commercially available, but was designed and built in the workshops in the Cambridge department.

The pace of exploration and innovation scarcely slackened over the next decade: during 1972-82 the Cambridge marine group ran another 39 expeditions at sea, consolidating our understanding of the structure and processes at work in the rocks beneath the oceans. In those days, before the huge land-grabs by coastal nations of "exclusive economic zones" offshore, you could sail a research ship almost anywhere. Matthews took full advantage of that, always choosing the most tractable problems in the most favourable locations. His laboratory was the two-thirds of the world that is covered by water.

Under Matthews's leadership the Cambridge marine group continued at the cutting edge of international science. One of his great strengths was in being able to draw on and to make full use of developments by theoreticians of improved models of how the Earth works and of new data processing and interpretation techniques, while at the same time keeping his feet firmly grounded in acquiring the best observational data possible. Often this meant developing new underwater instrumentation. This powerful combination of theoretical and observational capabilities in his research group drove numerous scientific advances.

Matthews's research group was characterised by talented and spirited graduate students, technicians and research assistants; who worked hard, sweated and laughed together as friends. Not a few of them ended up marrying one another. Matthews always led from the front: I cannot remember a single case of his asking someone else to do something he wouldn't have been willing to do himself. Indeed he frequently took on the most unpopular watches and menial tasks at sea himself. He was immensely supportive of his most junior colleagues and graduate students. It was typical of him that he left his name off the published authorship of some of the most important work that was done under his direction, giving the credit to his graduate students.

In 1981, having sensed that it was time to start something new because, as he put it, he began to bore his younger friends by saying gloomily when they came with bright suggestions that "we tried that 20 years ago, and it didn't work", he turned his attention to the continental rather than the oceanic crust.

His friend Jack Oliver, at Cornell University in the United States, had shown that with appropriate care you could use conventional seismic reflection techniques developed by the oil companies to look much deeper than they did, to the base of the crust and beyond. Matthews started a research group in Cambridge to do the same. Characteristically, rather than allowing this change of research direction to close down the Cambridge marine group he had led so effectively, he chose instead to resign his university post to allow a marine group successor to be appointed, and he put himself on temporary research money along with the rest of his new research group,

Thus was born the British Institutions Reflection Profiling Syndicate (Birps). It is a measure of his wry sense of humour that the second word was originally "Universities", but "Burps" as an acronym was perhaps more than his research council paymasters could stomach. The Birps group under Matthews's leadership was as successful as his marine group enterprise: it set new standards for deep crustal imaging, routinely recording complex and hitherto unknown structure in the lower crust and upper mantle, at depths of 10 miles and more below the surface. To geologists used to looking just at the surface outcrop of rocks, often, as Matthews himself put it, "scratching around in rabbit-holes", this added a whole new dimension to understanding the geology of a region.

In 1990, after a warning heart attack the previous year, Matthews took early retirement and spent the rest of his life gently encouraging his many friends and former students. He continued his lifelong enjoyment in sailing, first on a yacht and later, more genteelly, around the rural waterways of England on a small canal boat.

It is a measure of his mature leadership qualities and of the confidence and scientific rigour that Drum Matthews instilled in his students that both the research groups he built, the Cambridge marine group and Birps, continued to thrive after his departure. And perhaps the strongest testament to his scientific legacy is the many former students now in positions of leadership and responsibility elsewhere: between them they continue to make significant and ongoing contributions to the health of science around the world.

Drummond Hoyle Matthews, marine geologist: born 5 February 1931; geologist, Falkland Islands Dependencies Survey 1955-57; Research Fellow, King's College, Cambridge 1960-66; Senior Assistant in Research, Department of Geodesy and Geophysics, Cambridge University 1960-66, Assistant Director of Research 1966-71, Reader in Marine Geology 1971-82; Fellow, Wolfson College, Cambridge 1980-90; Senior Research Associate and Scientific Director, British Institutions Reflection Profiling Syndicate (Birps), Cambridge University 1982-90; FRS 1974; married 1963 Rachel McMullen (one son, one daughter; marriage dissolved 1980), 1987 Sandie Adam; died Taunton, Somerset 20 July 1997.