Why was Oakbank Crannog selected for research and excavation?
After a survey of Loch Tay in 1979, undertaken by Nicholas Dixon for his PhD research, discovered 18 crannogs, the only one which had obvious evidence of a timber walkway connecting the home to the shore was the site of Oakbank Crannog, named after a nearby cottage. Timber samples were taken for radiocarbon dating which suggested the crannog dated to the transition period between the Late Bronze Age and Early Iron Age, providing an exciting opportunity to learn more about the lives and settlements of some of Scotland's ancient loch-dwellers.
In the absence of government or other heritage funding, the subsequent work including survey and excavation of the site was undertaken privately for research purposes. Excavations were carried out with volunteers and students for short periods over a number of years, and discoveries and further radiocarbon dates place the site firmly in the early Iron Age. Details may be found in our Publications section.
Excavation underwater requires many specialist skills in addition to those needed for work on land sites. As Oakbank Crannog is always submerged, a special platform was erected in the water from which diving operations were carried out. Diving archaeologists used airlines to enable them to work for several hours at a time in the shallow water. The air was pumped by compressors on the platform tended by the dive team.
The crannog site was divided into sections, designated by a steel grid frame which also provided support for the working divers, keeping them off delicate areas of the site. Once the overlying mound of stones was removed in a section, the archaeologists faced tons of organic remains including structural timbers, woodworking debris and bracken which had been put on the original house floor. One of the most exciting discoveries was the last (uppermost) house floor used by the crannog dwellers. It was comprised of several parallel alder logs surviving over a distance of 5 metres - the only Early Iron Age timber house floor yet discovered.
Instead of using buckets, shovels and trowels as on land sites, the underwater excavation tools were dredges and dental tools. Dredges operate like vacuum cleaners, with suction provided by compressed air from the surface, to take away unwanted material. Dental tools were needed to excavate through the delicate, compressed organic material in which objects and timbers were embedded.
The final report on Oakbank Crannog has not been written because the excavation of the site is not yet complete. It relies on grant funding to carry out the work and for the conservation of artefacts and analysis of environmental samples. Funding permitted, the STUA plans to resume the exavation and survey of the site in the future as part of an exciting training opportunity provided in our field schools in underwater archaeology.