Digging on the Database

Article excerpt

'All new technology filters down into archaeology', said one practitioner for whom the computer has - almost - replaced the trowel. And why not? As an investigative discipline whose purpose often is to establish when, how and where new technologies were introduced, it is only appropriate that archaeology is itself relying on new technology more and more.

The Tony Clark Laboratory, opened by the Museum of London Archaeology Service (MoLAS) earlier this year and a major centre in Britain for archaeo-geophysical services, is a prime example of putting modern science to archaeological use. Its principal area of work, archaeomagnetic dating, is not inherently innovative; what makes the laboratory so valuable is its specific application of that technique in archaeological contexts.

Priorities for the five staff who work with MoLAS project manager Bill McCann include developing more efficient, user-friendly software to handle all the data involved, and refining even further the precise calibration curve extending from the present back to 1200BC.

Archaeomagnetic dating relies on the fact that iron oxides in such fired clay objects as kilns, hearths, pottery, brick, even burnt soil and some stone record the direction of the earth's magnetic field at the time of heating. Link changes of direction of magnetic field to precise dates, as Tony Clark has done, and archaeologists are ever grateful. Clark, who worked initially with the Ancient Monuments Laboratory and then independently, has donated his equipment (and his name) to MoLAS and is consultant to the laboratory.

Archaeomagnetic dating is more accurate than radiocarbon, says McCann, instancing how it has pushed back by twenty years - a small but significant change - the dating of one type of pottery common in medieval London.

But the laboratory's role will stretch beyond London, even beyond Britain. The aim is to carry out commissions from archaeological units outside the capital, and in the longer term to work with archaeologists abroad. While good archaeo-magnetic calibration curves exist in the United States and Japan, for example, much of Europe is poorly served - a gap MoLAS hopes it can help to fill.

A second major area of work is on ground penetrating radar (GPR), whose record in archaeology in Britain is less encouraging. GPR has huge potential for locating buried structures without the disruption of excavation, but there has been far too much hype surrounding it for McCann, who claims `We are trying to bring some sanity back'. …