Structure Twelve water trough adds to the evidence of food preparation

We’ve been talking with Jim Rylatt, Structure Twelve’s supervisor, and Jan Blatchford, who have been looking at the huge amounts of pottery recovered from that building. Here’s what they had to say about one particular discovery in Twelve… 

Jim, you’ve worked in Structure Twelve for many years now, so which particular aspect of the building are we going to discuss today?

Jim: While it may not have the aesthetic qualities and glamour of a carved stone ball or a polished stone axe, I want to talk about an orthostatic stone box that we uncovered in the north-east alcove of Structure Twelve.

So, what is an orthostatic box and why is it so special?

Jim: It’s a container with sides made using four slabs set vertically on edge, which rest on a larger horizontal slab and probably projected up to 0.3m above the ground surface when first constructed. 

It’s unique at the Ness, but not unique to the Neolithic of Orkney, as similar stone boxes were found within the houses at Skara Brae.

What was this orthostatic box used for?

Jim: Gordon Childe noted that the edges of the boxes at Skara Brae had been sealed with clay and deduced that they must have been created to contain water.

Perhaps influenced by the site’s current location on the seashore, rather than its landscape setting in the Neolithic, he decided that it must have been a live bait box, which had contained limpets.

We also found the remnants of a clay sealant adhering to the slabs of the Structure Twelve box, so I agree that it contained water.

But at the risk of picking a fight with one of my archaeological heroes, I don’t think it had anything to do with limpets, unless they were part of a nice seafood chowder!

When we had fully excavated the Structure Twelve box and taken it apart, we found that the sides were set on a much larger base slab.

This base slab was mid to dark grey but the area within the box was pale grey and the surface worn, with the ridges rounded off. The bleaching and wear to the surface is consistent with the box having repeatedly contained hot, or boiling, water.

In addition, it became clear that an earthfast anvil, which butted up against the box, had been erected at the same time because it sat on the base slab.

This anvil has a square top that had lots of dinks and divots from impacts, and our excavations between 2014 and 2017 revealed numerous hammerstones around the base of the anvil, including what looked like at least one complete tool kit consisting of several hammerstones arranged in size order, from golf-ball-sized to fist-sized. 

It looks, therefore, as if the anvil was for breaking animal bone to extract marrow.  

So, on the basis of these discoveries I think that we can be reasonably confident in interpreting the orthostatic box as a trough that was probably used for cooking.

And how would you cook with this type of trough?

Jim: Well, the sides of the orthostatic box, or trough, were about 0.4m high and enclosed an area of 0.4 by 0.3m, so it would contain around 25 litres of water when half full. 

People would place stones, probably igneous dyke rock or beach pebbles, in the adjacent hearth until they reached several hundred degrees. They would then transfer them to the trough, hypothetically using wooden tongs – but those kinds of wooden artefacts don’t survive – and drop them into the water in the trough. 

A series of small chips and incisions on the base stone were probably caused by these stones dropping onto it. The stones would shatter when the water was cold, as their outsides cooled down more quickly than their core, but the water rapidly heated up and it was possible to maintain a rolling boil by adding an extra stone every so often. 

Once the water was boiling, they would add meat or vegetables, much as you would today and providing you didn’t mind a bit of peat ash in your food, you would soon have a sizeable quantity of stew or broth.

Was there any evidence of what they were cooking in this trough?

Jan: There were some fragments of cattle bone in the fill at the bottom – pieces of a patella, a scapula and a long bone – but these might not be related to anything cooked in the box, as they were found with lots of pottery fragments that appears to be a deliberate deposit made as the final act of closure.

It is this collection of pottery that is really interesting.

It appeared on my desk a few weeks ago. The process of unwrapping piqued my interest straight away – a collection of 37 pottery sherds, all looking very different from each other. 

This wasn’t just the one vessel as I’d been expecting – there were five different pots. From the extrapolated diameter of the existing base sherds and the thickness of the body sherds I suspect that these vessels were all quite small and would have easily fitted in the palm of a hand. 

The clay matrix was different in each vessel, with some having a high percentage of rock temper and others made from sandy clay with no temper. Some sherds were co-joining, while others bore no relation to any others, apart from being part of the same “finds deposit”. All very strange!

What is a ‘finds deposit’?

Jan: It’s a term used on site to describe a collection of artefacts that appear to have been deliberately placed, rather than random pieces that are scattered throughout the midden.

In a typical finds deposit you might have several sherds of pottery, but they are usually from the same vessel. The curious thing about the pottery from the orthostatic box is the presence of at least five pots, which suggests that they were deliberately selecting fragments from different vessels to make up the deposit, rather than putting in a whole pot.

The curious thing about the pottery from the orthostatic box is the presence of at least five pots, which suggests that they were deliberately selecting fragments from different vessels to make up the deposit, rather than putting in a whole pot.

So, this particular collection of pottery sherds stood out from the general assemblage, but you must have looked at lots of the pottery from the site, how is this going to help us understand what was happening in Structure Twelve?

Jan: The ubiquitous presence of Neolithic pottery sherds is a characteristic of the Ness of Brodgar site that some archaeologists may find irritating as they work, each pottery find needing to be labelled, bagged up and geo-referenced before digging can continue. 

But for me this endless flow of prehistoric material is like treasure and is a constant source of interest and surprise. As the Ness dig ends, and the post-excavation gets under way, we have an amazing and precious assemblage of Neolithic Grooved Ware pottery that will be an invaluable resource for many ceramic archaeologists and specialists bringing modern scientific techniques to bear. 

Research involving chemical lipid and isotope analyses of pottery sherds is already ongoing. 

The pottery sherds give us a rare opportunity to discover, and reveal, hidden traces of those past lives. Understandably, after 5,000 years, complete pots are few and far between, but even the smallest sherd has a story to tell. What we discover will enable us to look at Neolithic pottery in new light.

Essential to the analysis of any collection of artefacts is the creation of an accurate catalogue. The daunting task of recording details of all those Ness of Brodgar sherds (probably numbering up to 100,000 by now) would be overwhelming if I thought too much about it, but the lure is without doubt addictive. 

The fascination has crept up on me slowly over the years, but I have found that the mundane task of counting, measuring and weighing bags of pottery sherds is countered by delight when closer examination reveals an unexpected aspect of their making.

Details hidden under layers of midden or soot are slowly revealed with careful cleaning and examination under a hand lens or microscope. Nick is having to get used to my excitement when I rush into his office to show him my latest find!

As a potter myself, I believe that I have an instinctive connection to those skilful potters of prehistoric times – I can feel their pain when things go wrong and their joy when things go right and am often amazed by the levels of technical skill, resourcefulness, artistry and manual dexterity evidenced in what I find. 

These people were highly accomplished and productive craftspeople who shared their knowledge and technical brilliance through generations of Neolithic potters.

Can you tell us anything else that was significant about the orthostatic box?

Jim: Well, two things spring to mind, both to do with the slabs that formed the sides. Firstly, the box, or trough, was constructed during the second main phase of activity within Structure Twelve, which occurred after large parts of the building had had to be rebuilt following a catastrophic collapse of the southern wall and the roof. 

We know this because the north-east pier fell during the collapse, and it would have obliterated anything in the alcove. The reason I am mentioning this is because the slabs forming the sides of the box have a comparable thickness to roof tiles, so it is possible that the box was constructed from left over tiles following the reconstruction. 

The rebuild really wasn’t very good, a proper DIY disaster, so there were probably lots of “spare” bits to dispose of or reuse!

Secondly, two of the orthostatic side slabs were decorated with incised lines. The relatively large slab forming the western side had an incised saltire extending from corner to corner and one of the quadrants was then infilled with a series of double chevrons. 

The other slab, which formed the northern side, had more irregular incisions dispersed across its surface. I think that we would see the trough as a fairly utilitarian object – the Neolithic equivalent of a large saucepan or cauldron – but the decorative embellishment could imply that Neolithic people viewed the preparation of food somewhat differently to us.

Overall, I think that this orthostatic box provides another strand of evidence that supports the idea that Structure Twelve was effectively a large, but prestigious, kitchen that was capable of providing large quantities of food for the people who were living at or visiting the Ness. 

And, in addition, it potentially provides a different interpretation of one small aspect of Skara Brae.