All photos by Philip Bell
Figure 1. A bog butter box unearthed in Castlederg in Northern Ireland, now housed at the Ulster-American museum there.
Something worth ‘spreading’
In our modern age, in order to preserve butter and other dairy foodstuffs, we typically store them in a refrigerator. But, the Scottish and Irish country folk of past centuries had to make do with a very different, though ingenious, method.1 First, they filled up a suitable container with the food item to be preserved—often a wooden pot but sometimes a wicker basket or an animal skin. Something like a muslin cloth seems to have been used to cover the contents or else a fitted wooden lid. They then lowered this into a local peat-bog—this is why these items are often called “bog butter boxes”.2
Figures 1 shows a specimen that was unearthed in a bog in County Tyrone, Northern Ireland, now on display at a museum near Omagh.3 I asked one of the curators to tell me more about it and quizzed him on whether the rocky contents of the wooden box were, in fact, ‘fossilized’ butter. He was adamant that this was the case. There is an obvious lesson from this. Since it didn’t take many thousands (let alone millions) of years for this to happen, it should beg the question in our minds “Does it really take such long time periods for fossils to form in history?” In the case of this particular bog butter, the answer is a clear, “No”. If the conditions are right, this kind of thing not only occurs but it can happen quickly—and notice that we’re talking of the hardening into stone of something which itself had no hard parts.
…finding these items in peat bogs is not uncommon, though … many of the specimens found are not mineralized, … they often have the appearance, smell and texture of cold, hard butter.
This was something that Charles Darwin thought could not happen, but reports of soft tissue fossilization are now commonplace, even of creatures like jellyfish!4 And finding these items in peat bogs is not uncommon,5 though it should be pointed out that many of the specimens found are not mineralized—although hundreds of years old, they often have the appearance, smell and texture of cold, hard butter. In one case, it’s said that the butter was sold at market as an edible material!6 But, there are other examples of ‘petrified’ butter, some said to date back to the time of Christ. Figure 2 shows a bog butter keg at the Cork Butter Museum (Figure 3) in the Republic of Ireland—it’s exact origin is not known. It was apparently hollowed out from a section of tree trunk and is reported to be 1,000 years old. What is particularly intriguing is that it was found to still have non-mineralized butter on the inside!
The anaerobic conditions in a peat bog … and the relatively constant, cool temperatures are known to retard decay. Presumably, this would keep the ‘bog butters’ from turning rancid.
Why bury butter?
Archaeologists used to be unsure about the precise nature of the ‘butters’—were they true butter or just degraded adipose (fatty) tissue from animals like sheep. However, a sophisticated chemical analysis of nine Scottish bog butters has established that most of them are true butter or dairy fat.7
As to why people should have stored butter (or similar products, like lard and tallow8) in peat bogs, the preservation of a valuable food for later consumption, perhaps during winter, is an obvious reason. The anaerobic conditions in a peat bog (oxygen is low or absent) and the relatively constant, cool temperatures are known to retard decay. Presumably, this would keep the bog butters from turning rancid. Other possible reasons put forward to explain the practice are that it might have improved the butter’s flavour, or that it was part of some sort of ritual, though the latter seems rather unlikely.
Certainly, there is plenty of evidence for these methods having continued for centuries, through medieval times and beyond. It may even have continued as late as the mid-nineteenth century in upland areas of Ireland.9 From the evidence of bog butter specimens found elsewhere, it is clear that similar practices were common in many parts of Scotland too, as early as the second century AD.10 One of these (radiocarbon-dated to AD 246–346) was discovered in Argyllshire by peat cutters in 1879. The researchers state, “The bog butter completely fills the vessel and the top surface is domed.”11 This is exactly what can be seen in the specimen in Figure 1 and is a common feature of many such archaeological artefacts—the butter is now (literally) rock-solid, a fact worth spreading around to give pause for thought to those who are wedded to the long-ages idea of fossil formation.
Figure 2. A keg of bog butter, thought to be from early Medieval times (around AD 1000), on display at the Cork Butter Museum.
Figure 3. The Cork Butter Museum, Republic of Ireland.12
References and notes
- It was not limited to these countries, in fact, and has been described in Finland, Iceland, Morocco and Kashmir, Ritchie, J., A keg of “bog butter” from Skye, Proc. Soc. Antiquaries of Scotland 75:5–22, 1940–41. Return to text.
- Other words used to describe them are ‘mether’ and ‘keg’. Return to text.
- The Ulster-American Folk Park, Castletown, Omagh, N. Ireland. Return to text.
- See: Catchpoole, D., Hundreds of jellyfish fossils! Creation 25(4):32–33, 2003. Return to text.
- In 2004, it was reported that more than 270 specimens had been discovered, some as columns of ‘butter’ a metre high and weighing up to 50 kg, New Scientist 181 (2439): 18, 20 March, 2004. Return to text.
- Information from the Irish Peatland Con-servation Council; ipcc.ie/infobogbutter.html, last accessed 6 August, 2010. Return to text.
- Berstan, R. et al., Characterisation of ‘bog butter’ using a combination of molecular and isotopic techniques, Analyst 129:270–275, 2004. (the journal of the Royal Society of Chemistry). Return to text.
- Strictly speaking, lard is pig fat and tallow is fat from cattle or sheep—both are solid at normal room temperatures. Return to text.
- According to information on display at the Ulster American museum, N. Ireland. Return to text.
- Earwood, C., Two early historic bog butter containers, Proc. Soc. Antiq. Scot. 121:231–240, 1991. Return to text.
- Ref. 10, p. 233. Return to text.
- Referring to the practice of preserving butter in bogs, they state: “Butter produced in this way was probably an acquired taste, but one which the early Irish may well have preferred.” Return to text.