What is a crannog? The simple definition would be that they are small artificial islets found in Scottish and Irish lochs (loughs) which were built mainly from the beginning of the Iron Age through the Early Medieval period (~800 BC-AD 800). From the few excavations which have been conducted on Scottish crannogs, there is a general consensus that people lived (at least part of the year) on these structures – a kind of island abode. They are commonly found now as rocky islets or fully submerged mounds, in fact, should you see a small island when passing a loch chances are very good that what you are looking at is a crannog. By some counts there are about 600 of these archaeological sites, but others have suggested the number is probably around 1000, many remaining undiscovered or unrecorded.
This is also where the above definition begins to break down, as most simple definitions do when examined in detail. First, there is one significant exception to the geographical spread of these sites as there is a crannog in Wales. There are also numerous examples of crannogs dating from beyond AD 800, with evidence for use on some crannogs right up until the 18th century. There is even a record of Queen Victoria and Prince Albert taking a picnic on Priory Island in Loch Tay during one of their early journeys to Balmoral. Going in the other direction, it has been suggested that crannogs (or at least building artificial islands) began in the Neolithic Period some 2000 years before the generally accepted Iron Age designation for crannogs begins (eg. Loch Olabhat, North Uist). Previous surveys of crannogs have also called for a more narrow definition of crannogs limiting it to artificial islands constructed primarily of wood. Such a definition would exclude many sites from the Western parts of Scotland and almost every identified crannog on the Western Isles. These stone islets are sometimes called rocky duns, and there are instances where other stone structures were built on them. All of this to say that crannogs represent a wide geographical and period range and therefore have an enormous amount of potential to inform on many aspects of Scotland’s history and prehistory. But it is not just their range that makes their potential so great.
Possibly the most significant characteristic of crannogs is their waterlogged condition. The cold dark water of Scottish lochs results in some of the most astounding preservation conditions in the British Isles and possibly the world. For example, at Oakbank, Loch Tay, underwater excavations there found a 2000 year old wooden butter dish. They knew it was a butter dish because there was butter still in it! Most crannog excavations have taken place on sites where the loch has been drained allowing archaeologists to excavate as if they were on a terrestrial site. Even in these cases the preservation has been outstanding with organic material surviving well beyond what is considered normal on other terrestrial sites of similar age.
Despite all this potential, you can count the number of crannog excavations since 1950 on your hands. There are a number of reasons for this, the biggest of which is the difficulty of excavating underwater or in waterlogged conditions. But, there have been huge excavations of waterlogged and submerged sites in other parts of Britain (egs. Star Carr, the Somerset Levels and the Mary Rose). It is time that crannogs get the recognition they deserve for being an archaeological resource in Scotland that is unmatched by any other site type in terms of artefactual potential, geographical range, and length of construction and use.
In attempting to explain what a crannog is, I hope that I have also laid out a good case for why we should study crannogs. This second question (why should we bother with crannogs?) is particularly important to me as I begin a PhD researching these infinitely fascinating archaeological sites. Over the next few posts I will describe my previous research on crannogs and where I think my PhD research will be going, please watch this space!