Geophysical prospecting methods used in archaeology, late 20th century.

Diorama of geophysical prospecting methods used in archaeology in the 1970s, built in 1977 by Mr Ley Kenyon. It is three feet squared and depicts the use of a prototype Martin-Clark resistivity meter to detect Roman ruins at the Stenness circle and henge at Orkney, Scotland during the 1970s. The diorama includes five miniature figures of people, one of which is Antony Clark, the co-inventor of the resistivity meter and head of the excavation. It features interpretative labels on slanting panels on all sides describing the history and principles of using resistivity measurements to detect buried ruins from the surface.

This diorama depicts archaeological excavations taking place at the stones of Stenness circle and henge in the Orkney islands. This henge is one of the oldest monuments in the British Isles, dating back 5000 years to the neolithic period. The site continued to be sites of active worship even into the 18th century, as a site of worship to Norse gods, a key stone being called the ‘Odin Stone’. The Stenness circle and henge is now a World Heritage Site.

A key part of this diorama is the team of excavators lead by Anthony Clark, who were testing a new method of archaeological surveying using a prototype Martin-Clark resistivity meter. This prototype was originally developed in 1956 by John Martin and Antony Clark and was designed to detect potential buried historical sites and buildings from the surface by measuring the resistivity of the soil.

Natural soil is typically less resistant to electrical currents than buried man-made structures usually made by compacted rock and gravel. By placing pairs of steel probes into the ground at set intervals and supplying them with an alternating current, the Martin-Clark meter can measure the level of electrical resistance between the probes, and estimate the likelihood of buried ruins and man-made objects.