Boglands pock Ireland’s countryside with blankets of undulating, desolate terrain. They are constitutionally bleak: acidic water permeates every nook and cranny of the spongy earth and a thick mop of Sphagnum moss on the surface occludes oxygen and heat, slowing both growth and decay to a frigid lull. But as the Irish, and many other northern communities, have found, boglands make for excellent refrigerators, and in Bronze Age Irish communities where butter was not only a food, but a currency and way of life, bog refrigeration transfixed and delighted.  

A blanket peat bog in Derbyshire, England. Martyn Williams, 2020.

As predominantly pastoralist cultures, Irish communities would migrate with their cattle into the hills during the summer and fall months. This practice, called booleying, capitalized on the late-season surge of grass in the ‘upland’ and gave pastures in the ‘downland’ time to recover from winter and spring grazing. While whole families would often move together (furniture and all), it was almost exclusively the work of girls and young women to milk and tend to cattle. Throughout their several month stay, these women produced butter at a staggering rate, stockpiling for the ‘lean season’ in surplus, when they would use their butter as both a source of nourishment and currency for trade. To keep their precious bounty from going rancid, they turned to bogs: packing the butter first into wooden containers, then burying it deep in the bitter muck.

A 2,325-year-old bog butter weighing almost 30 lbs recovered from Roseberry in County Kildare alongside the keg it was found in. National Museum of Ireland.

When the grass in the hills had been depleted and the cows had grown fat with its sustenance, the pastoral communities would pack up, unearth their hoards of butter, and venture back down from the booley. In the process of leaving, however, they frequently abandoned a container of butter or two, unable to locate them in the bog’s dark turf. Fast forward to the 17th century CE and the emergence of turf cutting in Ireland. As workers carved into the archaic bogs, harvesting crude, carbon-rich peat to burn for fuel and warmth, they occasionally stumbled across wooden containers stained black from tannins. The butter within these rediscovered kegs was notably changed, having hardened and yellowed from thousands of years underground; its taste, reportedly cheesy and acrid. It is rather paradoxical, however, that the desecration of the land which made dairy preservation possible 3,500 years ago is the primary means of learning about it.

Turf cutters harvesting peat from a bog in County Galway, Ireland. iStock Photo.

Now, as archaeologists and turf cutters continue to unearth these parcels, and with the advent of radiocarbon dating, an acting typology for bog butter containers has been established, permitting a more precise chronology of Irish pastoralism and reaffirming the roots of modern Irish civilization in the dairy industry. 

Further Reading:

https://www.smithsonianmag.com/smart-news/a-brief-history-of-bog-butter-180959384/

https://www.jstor.org/stable/26844466

References:

Earwood, Caroline. “Bog Butter: A Two Thousand Year History.” The Journal of Irish Archaeology 8 (1997): 25–42. http://www.jstor.org/stable/30001649.

Costello, Eugene. “The Lost Art of ‘booleying’ in Ireland,” August 31, 2021. https://www.rte.ie/brainstorm/2021/0422/1211486-booleying-ireland-summer-migration/.

Green, Cynthia. “Bog Butter Barrels and Ireland’s 3000-Year-Old Refrigerators.” JSTOR Daily, October 19, 2017. https://daily.jstor.org/irelands-3000-year-old-refrigerators/.

“Irish Bog Butter Proven to Be ‘3500 Years’ Past Its Best Before Date.” Accessed September 25, 2022. https://www.ucd.ie/newsandopinion/news/2019/march/14/irishbogbutterproventobe3500yearspastitsbestbeforedate/.

The Irish Times. “Saving Bogland: Stop Cutting Turf? I’d Say ‘No Way!’” Accessed September 25, 2022. https://www.irishtimes.com/culture/heritage/saving-bogland-stop-cutting-turf-i-d-say-no-way-1.4840017.