Introducing ceramics 5 – firing
By Roy Towers
So, our Neolithic Grooved Ware is formed, dried, decorated and ready for the all-important firing. What comes next?
You won’t be surprised to learn that archaeologists argue about this. (It is without doubt the most disputatious profession on the planet).
The generally accepted view on firing is that it took place in a shallow pit on which a bonfire was built.
This was the method used in experimental firings in Orkney conducted by Dr Richard Jones and it worked pretty well, reaching temperatures ranging from 600-900C. But bear in mind what we have already mentioned about the length of firing being at least as important for successful firing as the temperature in a bonfire.
Experimental work is one thing but actual evidence is what we need and that is notably absent in Neolithic Scotland.
Mound One was excavated a few years ago by a team from UHI led by Professor Jane Downes and Nick Card. You would recognise them still because many of those old lags went on to work at the Ness and are still there, albeit greyer and with sore knees and backs.
Also excavated was a nearby structure thought perhaps to be a “funerary house” associated with the barrow cemetery. It turned out to be an Early Neolithic house structure with, most intriguingly and just outside it, a feature which is now identified as a pottery firing structure, or perhaps a kiln.
We must be careful here.
In a kiln the pot to be fired is separate from the burning fuel while in a bonfire the burning material surrounds and works down through the vessels.
The Knowes of Trotty structure, which does not have a pit and where there is no evidence of material designed to separate fire and vessels, cannot, therefore be described technically as a kiln.
It does, however, have low, curving courses of stone enclosing the area and substantial evidence of organic material which may have formed an enclosing structure or clamp.
As it is built on the ground surface without a pit the Knowes of Trotty structure would have left little obvious signs for archaeologists, which perhaps explains the dearth of evidence existing today.
It is possible that the Ness pottery was fired in something similar to the Trotty structure, but could firing techniques or materials have changed in the intervening years?
We will leave the argument there, but the structure was only partially excavated and some of us are desperate to return and finish the job.
We will look briefly now at the obvious question about how the Ness pottery was used.
What was stored in it or cooked in it?
Regular readers of past excavation diaries will remember that the huge quantities of bone at the Ness suggests cattle-owning peoples and therefore a likely diet of meat and milk. This is confirmed by lipid analysis which detects fats absorbed into the walls of pots.
At the Ness, pilot projects have identified high levels of lipids in pot sherds. They divide roughly 50/50 into dairy lipids and bovine lipids.
We have no problem with meat. This could be roasted, although we have evidence of heat-cracked stones inside Ness vessels suggesting “stone-boiling”, where heated stones are popped into pots holding meat and water. The water boils and cooks the meat and, if this sounds unlikely, experimental archaeology has proved that it works.
Milk is a different matter.
Neolithic people are known to have been lactose intolerant; adults literally couldn’t digest milk without severe discomfort.
Penny Bickle, at the University of York, points out that ancient DNA analysis on skeletons suggests the lactase gene, which allows people to digest milk, is not noted before 2500 cal BC. Interestingly, that is the around the probable date of the end of Grooved Ware production.
What were they doing with all their milk?
We think they were making cheese, because the manufacturing processes separate curd from whey, which is where the majority of the problem-causing lactose sugars lurk.
One of our many tasks now is to find if dairy products are found in particular types of Ness vessel and if they had a special status. That seems to have been the case at the huge Late Neolithic site of Durrington Walls.
We’ll let you know.
Next: How to make your cordons stick, plus, we’ve got coloured pottery!