This summer we (the Rising Tides team – Caroline Wickham-Jones, Martin Bates and Sue Dawson) undertook a number of field trips in Orkney to cover a growing number of projects with partners at the University of Highlands and Islands.
Bay of Ireland
Moving south from our work in the loch of Stenness we have begun a collaboration with Scott Timpany at UHI, Jane Bunting at Hull University and Michelle Farrell at Coventry University. This project aims to contextualise the findings that UHI have published on around the peat deposits where a large oak timber was discovered by Ted Pollard during a campaign of coastal walking (Timpany et al., 2017). The Bay of Ireland opens into Scapa Flow, the infamous site of the scuttled German battle fleet from WWII. Our investigations however focus not on this rather on the very much older landscape during the early Neolithic when sealevel was still rising to that of today. This now submerged area is typical in that it has an infilling of both ancient and modern sediments. Our first task was to map these and determine the depth to basement (rock and glacial till). As with previous geophysical investigations it was also hoped that we might be able to see different layering within the sediments to discriminate packages that could be associated with different environmental conditions. We used the UHI Geoacoustic pinger for the initial survey. Results gave us the required depth to basement but the quality of data was not sufficient to image sediment packages. As can be seen by the map of basement depth the bay takes the form of a buried basin that deepens to the south.
|Map of depth to basement and example of sub-bottom profile, Bay of Ireland, Orkney|
The southern limit of the basin is marked by a submerged bank or barrier that stretches roughly east-west across the bay and separates it from the main part of Scapa Flow. Armed with this data we attempted to core through a thicker part of the sequence in the centre of the bay. The core penetrated over 2m of sediment that we now need to analyse.
At the same time as the marine work Scott also attempted to follow the peat layers offshore from the landside. A rather gloomy, wet day saw him joined by Martin and Sue with hand augers.
Following the geophysics and coring we were fortunate to be joined by Nat Hirst and Kerry Santander from SeasearchScotland. Seasearch divers usually scour the bottom looking at biology but they were game for trying their hand at underwater archaeology in the form of hunt the peat! Before diving Scott primed them on what sort of features we were after and we armed them with core tubes that could be inserted (bashed with a lump hammer!) into the seafloor. Over the course of two days they dropped on a number of sites both here and in the Bay of Firth adding greatly to our understanding of the conditions. Tough work but with the good weather a rewarding trip. Hopefully they can be encouraged to return when we have more sites for diving.
|hand coring on seafloor|
Skaill and Skara Brae
In September we returned to the loch of Skaill as our previous attempts to core this site had been thwarted by strong winds. The objectives of this investigation are aimed at further understanding the role of coastal barriers in protecting heritage sites. In particular we are trying to not only reconstruct the past environments around iconic settlements like Skara Brae but also to understand how the environment changed, and over what time periods it changed. Once again, the changes are not only linked to climate fluctuations but also to sealevel rise. It is likely that Skara Brae was first located some distance from the coast with a wetland between it and the sea. As the sea rose the coastal barrier was breeched and the land was flooded. Over the ensuing millennia the sea gradually eroded evidence for this land surface however the environmental conditions are still preserved beneath the site and in the surrounding landscape. For example, during coastal protection work at the site in 2009 a significant peat layer was noted at the base of the revetment scheme. Unfortunately, the works did not record this or sample for further environmental signatures. Published work by de la Vega et al in 2000 does provide a broad environmental setting for the site however our investigation aims to put far more detail into the story.
A series of cores both on the wetlands to the south of the site and in the loch of Skaill were taken and show a complex sequence of sand, peat and loch sediments. There will certainly be enough in here for environmental analysis over this winter. Based on these results it is intended to return to the site with a range of environmental geophysical techniques in 2018.
Orkney International Science Festival
September also features Orkney International Science Festival, an event that we try to participate in on an annual basis. This year we managed a great afternoon out with the P6 class at Dounby Primary School at loch of Skaill, a coring of the Peedie Sea with Scott Timpany at UHI as part of their project on Medieval Kirkwall, a joint exhibit of our palaeo-environmental reconstruction at the family day and a talk on the Borth fossil forest by Bates, Bates and Bates!! (my father, Denis and brother Martin giving the low down on joint work in mid-Wales).