For posts for the Three Lakes Biodiversity project see the menu on the right.

Spatial Analysis of Raths - or - Why Are They Where They Are?

One of the benefits of digital mapping is the ability to analyse the geographical distribution of features. This can apply to the combining of different layers in the maps, such as topography, geology and sediments, to get an idea of how they are related. And it can be used to great effect on man made features. In this regard an analysis of archaeological monuments in the countryside might throw up some interesting and otherwise hard to detect relationships. Such an exercise is being undertaken for the Raths in West Cork. The results will be presented on the Ringforts page of the WestCorkPalaeo website.

A screen grab from a digital map of raths on drumlins on the southern shore of Bantry Bay

Analysis of elevation, aspect (which way the hillslope they are on is facing), and angle of the slope can all be quite simply considered. Also the distribution of Raths within townlands, the size of the townlands and the number of raths in them, and the intervisibility of the raths. All of these aspects can only make use of the information we have, so in the case of intervisibility - which rath is within view of which other raths - this will be on the basis of topography. Whether forestry or hedgerows at some time obstructed the view we cannot know. We also cannot know what degree of visibility, if indeed any, was required. In assessing intervisibility we have to make assumptions about the height of the observer (you can see further standing up that you can sitting down) and also the height of the feature being observed (how high was a rath? well, it wasn’t flat). A column of smoke will make a rath visible by rising 20 , 30, 40 metres into the sky above - is this a relevant consideration to hold?

We also do not know, and can only guess, at the considerations that are given to where raths were sited. Was the nearness of water a factor? Or the closeness to a relative in their rath? Did the quality of the ground - deep soil for the souterrain underneath the rath, rocky subcrops for a firm and non muddy base - make a difference? There are many possible factors.

So there are obvious problems in making these assessments, and many pitfalls that could be fallen into, all of which need to be borne in mind when undertaking spatial analyses. Giving consideration to raths of West Cork requires validation as well. The county boundary probably wasn’t in existence at the time, so when looking at regional groupings of raths, we need to try to understand the geographical groupings. Was it by peninsula, different ranges of hills and valleys, specific river drainage areas, areas of rock type or sediment type - like the difference between limestone and sandstone, or boulder clay and peat? There is an assumption that townlands probably date from the same period as raths, so is it relevant to assess the number of raths in each townland? We know that some townlands have been split, or newly created, as a result of relatively recent changes in land ownership, certainly long since the rath period.

Digital mapping does at least allow the examination of the landscape and it’s features to a level of detail not normally afforded by conventional maps, with the possibility of including calculated layers (such as an intervisibility network), and layers of data of disparate sources - geology, archaeology, environment, hydrology etc. Various ways of portraying the topography can be explored, such as contours at various intervals, and hillshading. The image above shows a group of raths on the southern shore of Bantry Bay just south of Whiddy Island. This is an area of drumlin hills - two drumlins can be seen ‘sliced open’ by coastal erosion on this part of the shore, at the western facing beaches. The red dots are raths, the white are souterrains (within the raths); red lines are roads and tracks, black lines are townland boundaries, contours are at 1m intervals. The yellow lines are the rath’s intervisibility network - by which one rath has line of sight to another, or not, according to the topography. Black patches are rock outcrops. An image of a larger area at smaller scale, with 5m contours, is shown below.

A smaller scale screen grab from a digital map of raths on drumlins on the southern shore of Bantry Bay

Seeing this representation can raise all sorts of questions - why were the raths built on these drumlins? Why so close together? Did they therefore have smaller parcels of land? Were they even farmsteads?

I have yet to visit these raths to see them in the flesh which is, of course, the best and ultimate way to understand a feature within the context of the landscape.

Finally, while experimenting with visibility networks, what was visible from these raths situated on the drumlin tops? This third image shows the viewsheds of the drumlin raths; these raths are red, all other raths are purple. The shades of green signify visibility - to all intents and purposes we can say that the dark green areas are those that were not visible from our raths on the drumlin tops, all other shades are areas that were (and presumably still are) visible. The yellow lines are the lines of vision between raths, from the drumlin raths outwards. Visibility range has been extended to 10km.

The areas of visibility of the drumlin raths on the southern shore of Bantry Bay