collapse, but not failure…

It is with mixed feelings that I find myself having to describe the collapse of our Mesolithic house which managed to stand for a somewhat shorter period of time (three months) than we had hoped . We think that the collapse was caused by failings in our understanding of the materials and the execution of the construction, not the design itself and hope to revisit some of these problems in a future rebuild. The collapse has also given us lots of really useful information about these structures, and in this sense the experiment has still been succesful. But firstly, I should explain what happened.

 

final_with_full_roof

Final house with thatched apex, Sept 11th 2013

 

 

 

 

 

 

 

Following the ‘completion’ of the house in late July, we did a first batch of running repairs. This mainly involved patching areas where the turf had slipped and placing a thatch cone over the apex of the building. This was undertaken in early Sept. Following this, we began to monitor the structure and soon spotted that some poles were showing signs of strain.

 

Pole 1, bent and cracked. Sept 2013

Pole 1, bent and cracked. Sept 2013

 

 

 

 

 

 

 

The first pole (pole 1) to split was a very thin birch, which bent inwards and cracked. This had supported parts of the door and porch, and was a bad choice of materials on our part. We repaired this section by ‘tying in’ the bent pole with bands of wattle. In late Sept we noted a more substantial crack in another pole on the same side of the building. Both breaks were 2 – 3 m from the apex of the structure.

 

House, October 2013, note bowing in of left hand side

House, October 2013, note bowing in of left hand side

 

 

On 21st October we spotted a substantial crack in one of the main timbers that formed our original tripod, again on the same side of the building as the other timbers. This time around, repair was not an option and we shifted our focus to monitoring collapse. The bowing inwards of the whole of that side of the building is very evident in the photographs.

 

By 23rd October this pole had snapped clean through. We sampled the timber, which appears to have suffered a straightforward mechanical failure: there is no evidence of rot. (see below for further discussion). Following this, the final collapse during a week of very heavy winds and rain was very rapid.

Pole7_clean_snap

Clean break of Pole 7, OCt 23rd 2013

 

 

 

 

 

 

 

Sad looking house, October 25th 2013

Sad looking house, October 25th 2013

 

 

 

 

 

 

 

The collapse of the house has caused mixed emotions. Whilst we would have loved the building to have stood for longer we are already learning a great deal from the processes of collapse. Firstly, once a structural element of the building breaks, collapse is rapid and systematic: once a certain point is passed, all of the timbers break and would not be reusable. Secondly, we are already getting a sense of how artefacts incorporated into the roofing turves spread, in some places appearing at some distance from any visibly collapsed turf. We will continue to monitor this which is providing very valuable information about the spatial distribution of arcaheological materials.

Of course, we want to know why the house collapsed. At this stage we see four possible explanations, many of which are connected

- the bad weather led to overloading of the structure through waterlogging and wind damage

- the birch trees were not strong enough. We used birch saplings which had started their life in a nursery. At the break, the tree lacks many rings and is not as structurally robust as an older, slow grown birch may hav been.

- related to this, failures on our behalves in terms of skills, understandings of the materials and poor execution weakened the house. We will explore this in more detail in the coming weeks but this explanation might include: not understanding how much curvature and twist could be in a ‘straight’ pole; not managing to keep a consistent circumference because of this curvature; failing to place sufficient wattling in place.

- finally, it is possible that the design was simply not appropriate for a turf roof and that buildings of this type were covered in thatch, skins or possibly had internal supports for which we have no archaeological evidence.

We cannot fully differentiate these explanations, but we feel that a combination of the second and third are most likely: the failing of the building ultimately reflects our lack of skill and understanding of the materials. We are currently considering how to remedy these problems in a rebuild for early 2014.

There is much more to consider about the collapse of the house. This was always an experimental archaeology project and in these senses it has been successful – we know much more about these buildings, their potential forms and how they behave than we did when we started. If it is back to the drawing board it is a much more informed and knowledgable way! At the same time aspects of the experiment continue, as we monitor the collapse of the house and try to understand how and why the different materials behave. We look forward to keeping you updated with these developments.

 

building mesolithic in the news…

A key aspect of this project was public engagement – taking the opportunity to promote archaeology, experimental archaeology and the study of the Mesolithic and hunter-gatherers in general. I’m delighted that we’ve been able to work with a number of different agencies to produce short pieces (and one longer one, of which more anon). My thanks to all the students for their patience in facilitating the filming, to Philip Bromwell (RTE) and Dominic and Andrew (UCD).

The RTE 6.1 News film

The UCD film

Greg filming the interior of the house

Greg filming the interior of the house

Raising the Roof – and surviving the floods

The house is finished. After two days (Tues/Wed) of non-stop work we’ve laid a turf roof over the entire structure.

smoke rising from our fire

smoke rising from our fire

 

 

 

 

 

 

 

 

The timber and wattle frame support c10-15cm thick turves, cut from the grass in the Experimental Archaeology Centre.These were pegged into place with short lengths of willow. Following drought conditions the turves were terribly hard to cut and handle – and the red ants infesting most of them made things rather unpleasant. It was two long days of warm and sweaty work. I’m very grateful to everyone for their help.

Niall putting the finishing touches to the apex

Niall putting the finishing touches to the apex

 

 

 

 

 

 

I’ll write some more about the structure shortly, but its worth noting that the weight of the turf is substantial, and the framework is holding it easily. The outreach component of the project continued – we had three separate people filming the process for different organisations. Mark Kelly’s ‘School of Irish Archaeology’ visited this week and last.

Bernard and children from the School of Irish Archaeology

Bernard and children from the School of Irish Archaeology

 

 

 

 

 

 

 

 

The house is a remarkable space, and has also been put to a robust test. Last night saw severe thunderstorms in Dublin. Hospital and shops suffered damaged roofs in the storms (see story in the Irish Times ) which saw a remarkably heavy downpour. I arrived at UCD this morning expecting to see our painstaking work destroyed.

House after major thunderstorms

House after major thunderstorms

 

 

 

 

 

 

 

 

In fact only two turves had slipped from the apex of the building. The inside floor was wet – we still need to patch some holes – but the interoir of the walls was dry – it seems that the water sheeted off the structure. In general our handiwork had lasted the storms better than some large scale modern buildings.

Building a Mesolithic House has been a fantastic project – huge fun and really informative. I’d like to thank everyone for their contributions. It is important to note, however, that buildling the house was only part of the project – many of the experiments will only being now. I look forward to updating you about these in the coming weeks.

Building the framework

Work on the house has resumed over the last few weeks, with the focus being on getting the timber framework up. We’re very grateful to Eoin Donnelly for advice and expertise in this process.

The framework of the house is based on the Mt Sandel ground plan. We’re using long birch trunks, set at an approximate incline of 30 degrees. The first challenge is in getting the first poles in place. This is done by tying three poles together (note our lovely lime bast cordage) and raising them as a tripod, using ropes to provide lift.

Eoin Donnelly's excellent knot holding the tripod together

Eoin Donnelly’s excellent knot holding the tripod together

Raising the tripod

Raising the tripod

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Once these are in place, other poles are laid against the apex, and the whole tied into place. All the birch poles were placed in post holes, the dimensions of which were coherent with those at Mt Sandel.

Maeve, Julie, Christina and Eoin move more poles into place

Maeve, Katherine, Julie and Eoin move more poles into place. Cian takes photographs.

Eoin tying the apex together. Modern ladder required for Health and Safety permissions!

Eoin tying the apex together. Modern ladder required for Health and Safety permissions!

 

 

 

 

Mark and Tipper dig a post hole under the watchfull eye of Eoin and Cian

Mark and Tipper dig a post hole under the watchfull eye of Eoin and Cian

 

 

 

 

 

 

 

 

Following the creation of the main birch frame we have used willow wattling to bind the structure together and provide a framework on which to lay the roof. We placed single stakes between each birch and may add more later to support the turf. This wattling has been time consuming work, but has generated a very stable building.

House with wattle bands

House with wattle bands

View of porch

View of porch

 

 

 

 

 

 

We have added a porch to the framework. There is no direct archaeological evidence for the form of the porch, but it seems likely that one would have existed otherwise water would enter the building. We have used hoops of willow and integrated this to the wattling. The only footprint to the porch is two stake holes.

Next week we will try and lay the roof: harvesting turf and laying it on the framework created. Fingers crossed it works!

Plant fibre cord

One of the things that sometimes gets forgotten in understanding prehistoric lives is the importance of cord.

Lime bast cord

Lime bast cord

As with many materials, when we buy string from the shop we rarely stop to consider how it might have been manufactured, and the time involved in it. Our house is going to require fastenings of different kinds to hold it together. There are a range of possibilities of materials to use; ligaments or sinews of animals, roots or young withies of trees for example. We were also keen to make some plant fibre cords. We know that string was used in the Mesolithic in Europe and must have been made in large quantity – there are fragments of fishing nets from Mesolithic Denmark. Making string must have been a time consuming activity, and was likely a routine aspect of life: undertaken whilst sitting talking or watching or waiting.

Close up of lime bast cord

Close up of lime bast cord

We have been using lime bast to make cord. Bast is a papery material found under the bark of trees. (It should be noted that lime would not have been frequent in the Mesolithic in Ireland, although it was present in the Neolithic. We’re very grateful to John Nicholl for procuring the bast for us). We have been plaiting the bast into cord of different widths. This is a very simple procedure (just like plaiting my daughters’ hair, but without the complaints about tugging on the knots) which is surprisingly therapeutic.

We managed to make lengths of cord over 5m long in a few hours, and of course, we will have been working more slowly than prehistoric people would have. The cord is very robust and has very attractive aesthetic qualities.

Julie at the end of a long piece of cord she made

Julie at the end of a long piece of cord she made

 

Prof Gabriel Cooney tries his hand at string production

Prof Gabriel Cooney tries his hand at string production

Tree felling

After a lot of planning and organising, on Friday 22nd Feb we were able to get underway with the practical side of the Building Mesolithic project – felling some of the trees that will form the structure. Gaining permission to fell the trees has involved a lengthy process of liaison with colleagues in UCD Safety Office and UCD Buildings and Grounds. We’re very grateful for their help, and delighted that we have been granted permission to fell a small number of trees on UCD Campus. My colleague Conor McDermott, our field and lab officer, has spent a long time ironing out details of risk assessments etc – not a glamorous or exciting task, but essential to an activity like this. I’m very grateful to him. We would also like to thank Dr Brian Tobin from UCD School of Agriculture & Food Science (Forestry), who gave us a safety briefing and helped in the field.

We are harvesting a small number native timbers (mainly birch and hazel) from limited locations on UCD campus, following extensive liaison with UCD Grounds. Timber is only being felled in areas where thinning of woodland is required to promote the growth of hard wood trees (oak, beech etc). The timing and location of felling reflects the importance of UCD woodlands as a wildlife habitat. In particular, we must finish felling before the birds start nesting.

My daughters, Sadhbh (age 8) and Molly (age 6). Both ground serviceable blades onto cobbles in about 70 minutes.

My daughters, Sadhbh (age 8) and Molly (age 6). Both ground serviceable blades onto cobbles in about 70 minutes.

We worked in two teams, and focused on getting used to carrying out this task, dealing with the safety issues, and thinking about how to properly record the data gained from this experiment. We cleared areas of undergrowth, worked out escape routes, and fenced areas off from the public. All of this takes time. In the end we felled two birch trees using stone axes made by students over the previous weeks (we’re very grateful to the UCD Prehistoric Flintknapping Group for their help here).

 

 

The trees were small (10-15cm diameter) and took only 16 minutes of chopping to fell. Of course, Mesolithic individuals were much more skilled stone axe users than us, and would certainly have taken less time. The axes (one per tree) were bagged after use with records of the tasks they were used for. Once felled, the trees were trimmed of side branches, and carried to the Centre for Experimental Archaeology. The trees took 2-3 people to carry in the end.

The tool marks on the trees are very interesting, and closely paralleled on archaeological assemblages of waterlogged wood. We will record these tool marks carefully to provide a reference collection.

Brendan, an axe and a tree. (c) Aidan O'Sullivan

Brendan, an axe and a tree. (c) Aidan O’Sullivan

 

Birch tree, c 10cm diameter, after felling with stone axe. Note tool marks and splitting. (c) Aidan O'Sullivan

Birch tree, c 10cm diameter, after felling with stone axe. Note tool marks and splitting. (c) Aidan O’Sullivan

 

 

 

 

 

 

 

 

 

 

 

Greg films, Chris hits a tree with a stone. I assume supervisorial posture. (c) Aidan O'Sullivan

Greg films, Chris hits a tree with a stone. I assume supervisorial posture. (c) Aidan O’Sullivan

 

 

We have entered a film competition with students from IADT to try and raise a small grant to make a short science film about the process. Greg and Ana were with us on Friday and got some fantastic footage. I’ll write more about the film in due course.

Many thanks to everyone for their work so far. The next task is to fell more trees: having got a better sense of the work involved in felling, we can work much more efficiently next time, and gain better scientific data as well.

Welcome

Welcome to our blog. This reports on a UCD School of Archaeology project that aims to build a Mesolithic (middle stone age)  house in the Centre for Experimental Archaeology at UCD. Basing our experiment closely on archaeological data, we will use stone age technologies and materials in an attempt to learn something of the real conditions within which these remarkable structures were built.

In the centuries following 8000 BC a distinctive architectural tradition appears in the archaeological record of Mesolithic Ireland and Britain. These large (sub-)circular post-defined buildings with central fire places were constructed by groups of hunter-gatherers. They are the earliest type of building found in Ireland and amongst the  earliest architectural forms in Britain. More are being found frequently by archaeologists – with four new houses reported over one week end in November 2012. For details see news stories in the Guardian and the BBC.

The buildings are generally c 6m in diameter, circular or sub-circular in shape and located within shallow artificial scoops. Their perimeters are defined by timber posts and stakes and the roofs are generally considered to have been of turf, hide, bark or thatch.   They are generally interpreted as houses, and they are often reconstructed repeatedly on the same location over the span of 100-150 years. The large size and clear permanence of these buildings is a challenge to many of our ideas of Mesolithic settlement which have tended to stress that people were highly mobile and characterised by little in the way of permanent architecture: matching many current stereotypes of hunter-gatherers.

Early stage planning discussions at the Centre for Experimental Archaeology. The flags mark out a 6m diameter circle. Its worth noting how many people are stood insde. Photo (c) Sonja Laus

 

 

 

 

 

 

 

 

These early buildings raise many important questions about the nature of Mesolithic life. This includes practical issues about architectural features: the nature of the roof, and the overall shape of the structure, but also encompasses broader interpretative themes:  why are so many of these sites repeatedly reoccupied on the same site? How long do they last? How many materials and people are needed to construct these buildings? These questions can be approached through the techniques of experimental archaeologym which involves the creation of objects, buildings, activities and contexts, through which ideas about people’s lives in the past can be thought about in practical terms.

We are currently in the planning stages of the project, and will begin construciton in the New Year (2013). We would welcome volunteers, comments, advice and any offers of materials! The blog will be updated intermittently in the planning stages, more frequently once construction begins.