01 October 1997

Hidden landscapes revealed in colour

Lovelace recently had cause to chide Mr Babbage for his failure last month to attribute correctly the phrase "raining floppy disks" to its creator, Mr Richard Dawkins. Babbage claims distraction by a street musician, but Lovelace is more inclined to attribute the lapse to his advancing years.

Inspired to musings on the passage of time, Lovelace was speculating on how differently the great archaeological excavations might have proceeded, had there been access to modern geophysical equipment. At Nimrud, Layard employed dozens of workers in digging trial trenches to trace walls that nowadays could be mapped with a magnetic or resistivity survey. J Turtle Wood took seven years to find the Temple of Diana at Ephesus, following, by intuition and more digging, the temple road buried under 25 feet of alluvium: a situation where now cart-mounted ground penetrating radar (GPR) excels.

However, whilst geophysics provides us a magical eye for seeing into the earth, presentation of its findings is frequently lacking in impact. Lovelace was interested to hear of the Computing Archaeology Research Group at Staffordshire University. Led by Mr Mike Fletcher, the Group uses personal Babbage Engines to interpret and display geophysical data in a fresh and visual form.

One benefit is the Engine's power to explore the relationships between data gathered by different techniques. For example, correlating magnetic and topographic data can distinguish true underground data from that due only to undulations of the terrain. Beyond this, Lovelace found highly appealing the scope of Engines to attractively display archaeological results.

One striking example is the depiction she saw on the Group's World Wide Web page of a resistivity survey of the Hindwell Enclosure, a prehistoric farm site in Clwyd. No dull contour map this, but a three-dimensional model rendered by Engine and green-painted to resemble a field. The domains of low resistivity - the silted hollows of the surrounding ditch, a quarry, and a run-off channel - appear as dips, thus recreating the enclosure as a delightful imaginary landscape.

This is no idle prettifying of numbers. Such techniques, Mr Fletcher argues, aid the appreciation of results by the onlooker, and can only be an improvement when the publication of geophysical findings in archaeology is often still in the 'map and lantern-slide' format of the lectures Mr Babbage found so tedious in his time at Trinity.