Obituary: Anthony Clark

Anthony Clark contributed much to archaeological science, but will be remembered particularly as a pioneer in the use of geophysical prospecting methods which are now indispensable to much practical field archaeology.

By means of fieldwork and example he demonstrated the archaeological potential of a series of novel instrumental techniques which now form the basis of a small industry. He did this with a directness and originality which he would have been pleased to see as part of a worthy British tradition of underfunded scientific ingenuity, but also brought to his work the methods and awareness of a skilled field archaeologist.

Clark was conscious of following in the tradition of such notable earlier archaeological fieldworkers as I.D. Margary and O.G.S. Crawford, with their emphasis on the continuity and significance of each detail of the landscape, and he wished to extend their methods by introducing new sources of evidence. His archaeological career began when he was a precocious schoolboy excavator, and continued when he managed to turn even the experience of National Service to relevant effect.

He trained in aerial photographic interpretation with the RAF at Nuneham Park in Oxfordshire, and heard during this improbably military interlude of the early experiments with resistivity surveying which Professor Richard Atkinson used to detect ploughed-out barrow ditches from 1946 onwards at Dorchester-on-Thames nearby. This encounter made a lasting impression and in 1956 Clark, together with a colleague also employed at the instrumentation laboratory of the Distillers' Company, developed the Martin Clark resistivity meter. This was a lightweight device specifically intended for archaeological work, the prototype of which later found a place in the Science Museum.

Clark devoted much effort in subsequent years to experiments investigating the complex climatic and seasonal influences on the resistivity response from a variety of archaeological features, and this work later formed the basis of the thesis for which he was awarded a PhD by Southampton University in 1980.

In 1967 Tony Clark was appointed to be the country's first full-time specialist in archaeological geophysics at the Ancient Monuments Laboratory, which formed part of the Inspectorate of Ancient Monuments at the then Ministry of Public Buildings and Works. Archaeological prospecting requires intensive ground coverage to detect the minute physical traces of past human activity, and so remains a laborious pursuit. Clark found this to be particularly the case in his single-handed early days, but he at length built up a team which continues as part of English Heritage today.

From the late 1960s, magnetometer surveying, which had previously been investigated at the Oxford Archaeology Laboratory and elsewhere, became a more practical option following the development of a new and more portable magnetometer in response to police requirements for ground searching equipment. Clark was responsible for a series of classic demonstrations of the value of this device, which he applied with characteristic directness. He walked across Hampshire watching a flickering dial, and thereby added significantly to the archaeological record along the line of the proposed M3.

By similar methods, combined with an interpretative boldness which few of his colleagues would have cared to match, he identified the campfire sites of the original builders behind the ramparts of an unfinished Surrey hillfort, and with an elegant economy of method he sorted a number of Hampshire hillforts in the course of a day into occupied settlements and uninhabited refuges.

Clark also did much to promote the acceptance of magnetic susceptibility surveying, another technique which emerged from the Oxford Laboratory as a means of predicting the suitability of sites for magnetometer surveying. Clark showed that his method could be used to locate areas of ancient habitation by means of extensive sampling, and so established a procedure which has been widely used in recent years for large-scale archaeological evaluations of road routes and gravel sites.

His initial tests of the method included a study of an Iron Age cropmark site which showed, by comparison with results from the complementary geochemical technique of phosphate analysis, that areas of human occupation could be distinguished from prehistoric cattle enclosures purely from surface measurements in an open field. He also similarly identified a possible hearth at the centre of Coneybury Henge, thus providing a hint as to the nature of ancient events at this vanished neighbour of Stonehenge.

Another complementary area of work at the Ancient Monuments Laboratory was the development of magnetic dating, which is a technique based on measurements of variations in the earth's magnetic field direction, as preserved in samples of burnt clay and other materials. This method was revived in the 1970s by researchers at Newcastle University, but required large numbers of calibration samples from sites dated by other methods before it could be widely applied. A practitioner of the method must therefore be prepared to rush immediately to retrieve samples from any site where suitable material is excavated. Clark bore this for many years and contributed substantially to a body of calibration data published with colleagues in 1988.

Tony Clark was not entirely in his natural element in the Civil Service, and viewed the prospect of joining the new English Heritage with some suspicion. He therefore took the opportunity for retirement rather than transferring with the Ancient Monuments Laboratory to the new organisation, and became an independent consultant from 1986.

This led to a highly productive period in which he continued his dating work, until with some relief he was able to hand this particular torch to the Museum of London, to which he presented his equipment, and which opened the Clark Laboratory named in his honour in 1996. He also participated in numerous increasingly ambitious geophysical projects for which a demand emerged following the introduction of the novel principle of developer funding to British archaeology in the early 1990s.

Clark's book Seeing Beneath the Soil (1990) was, like its author, difficult to accommodate within a narrow academic category. It shares some of the characteristics of an archaeological memoir of fieldwork handbook as well those of a scientific textbook, and provides a careful record of much significant early work. He was dismayed by the scornful review it received from a bemused theoretician, but was consoled by healthy sales.

The book has gone into a second edition and attracted sufficient interest in Japan for the publishers to commission a recently completed translation.

Anthony John Clark, archaeologist: born Guildford, Surrey 22 March 1930; married 1966 Una Millet (died 1996; two sons); died Farnham, Surrey 3 June 1997.