Underwater Archaeology Research Centre
  • Print
   
   
 

Loch Glashan Crannog, Argyll and Bute

This collaborative project carried out high-resolution side-scan survey of the reservoir at Loch Glashan in order to locate and sample a previously excavated site.

The survey was funded by Historic Scotland and carried out by members of The University of Nottingham Underwater Archaeology Research Centre and the Centre for Maritime Archaeology, University of Ulster.

Sidescan survey on Loch Glashan
 
Project overview

In 1960, the Loch Glashan crannog was exposed by the lowering of the waters of the loch as a low mound partly covered with stones and a number of upright piles visible beyond the feature’s edge.

The site was excavated by Mr and Mrs Scott in the same year prior to the re-flooding of the site in the autumn of 1961. The excavations revealed the crannog’s structural remains of oak and birch piles as well as a large assemblage of finds that indicated an occupation between about 500 AD and 850 AD.

In 2003, and while the crannog remains were submerged, our team located the remains of the site and produced high-resolution side-scan survey. The remains of the nearby submerged medieval island settlement were also located.

 
Project methodology and outcomes

The aim of the survey was to locate the Loch Glashan crannog and to produce an underwater survey of its full extent and the location of piling around its perimeter. The site of the crannog was located in 16 metres of water lying some two metres under very soft reservoir silts.

The very soft nature of the silts and the relatively deep nature of the site created very poor visibility resulting in treacherous diving conditions; divers had to be either tethered to the boat or diving in scuba buddy pairs for safety. Soft fluidised silts and muds are commonly found in reservoirs and are sometimes referred to as ‘ooze layers’. Sonograph traces of the crannog were only obtained by changing the resolution of the side-scan sonar to penetrate silts.

The sonograph trace of the site obtained in 2003 is directly comparable with the plan of the original excavations produced by Scott. The close correlation in size and shape would suggest that Scott recorded the majority of the structure at the site and that there is little more beyond the margins of his original excavation.

A nearby submerged medieval island settlement, thought to be the site of an Early Christian Church, was also located at a depth of 9.4 metres. The tops of walls protruding from the silt were visible at depths of 9.4 metres, standing just a few courses high, but they quickly disappeared into very thick, soft silts from depths of 10 metres. From this depth all that is visible is silt as the entire island has been covered. The margins of the island are totally obscured by very fine, soft lake silts, and as a result there is little indication of the existence of the island itself when examined underwater.

 

Project team

Dr Jon Henderson (University of Nottingham)

Graeme Cavers (AOC Archaeology Group, Underwater Archaeology Research Centre, University of Nottingham)

Members of the Centre for Maritime Archaeology, University of Ulster

 

Underwater Archaeology Research Centre

The University of Nottingham
School of Humanities
University of Nottingham
University Park
Nottingham, NG7 2RD


telephone: +44 (0) 115 951 4842
email:jon.henderson@nottingham.ac.uk