‘Rock matters’ – Ness geologist’s PhD thesis available online

Dr Johnson at work in dig HQ. (Jo Bourne)

Dr Johnson at work in dig HQ. (Jo Bourne)

Last year we congratulated Martha Johnson, our resident geologist, for gaining her PhD for her thesis entitled Rock matters: A geological basis for understanding the rock at the Ness of Brodgar.

We are now pleased to say that her full thesis is now available online – click here to download. A little light reading to keep you busy during these strange and surreal days.

“Martha’s thesis is a brilliant piece of work that will have implications for any archaeological excavation,” said Ness site director Nick Card.

”We have been very fortunate to have had our own geologist working on site. Martha has given us an unparalleled insight into the material used to construct this 5,000-year-old complex.

“Her research has also raised many questions about the large quantities of apparently unworked, non-building rock deliberately brought on site — questions every prehistoric excavation will want to ask.”

Abstract from Martha’s PhD thesis:

A small selection of water-rounded rock collected from the Ness.

This research introduced a geological perspective into an archaeological setting, the Ness of Brodgar, a Middle to Late Neolithic site in the West Mainland of Orkney.

Discovered in 2003, the site is located on an isthmus of land between two lochs and is equidistant between the Ring of Brodgar and the Stones of Stenness stone circles. The site consists of more than two dozen drystone buildings encircled by a massive wall. To date, ten per cent of the site has been excavated.

This research established a systematic framework of protocols and procedures for the recovery, macro geological assessment and identification of the rock and mineral species in the non-tool, non-structural rocks, termed Foreign Stone for this research.

Sedimentary examples.

Once identified, the frequency and distribution of the rock in the Foreign Stone finds were calculated, providing a geological basis for understanding any patterns of rock choice across the site. Integrated into a more conventional archaeological study of the Worked Stone artefacts was a systematic macro petrological analysis of these finds. Additionally, selected segments of the interior drystone walling were assessed to identify the rock in the various members.

These petrologic analyses combined to provide insight into the range of rocks transported to and utilized within the site. Comparative analysis of the data from all three aspects, Foreign Stone, Worked Stone and Walling, was undertaken to identify trends in frequencies and patterns of use of the various rock species.

Archival and more current information on the petrologic resources available within Orkney were synthesized in a gazetteer identifying the location(s) of rock outcrops and deposits. This permitted the source location(s) of many of the rocks from the Ness of Brodgar to be identified.

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