Why ancient butter keeps turning up in Irish bogs

In bogs across Ireland, people keep stumbling into their forebears’ valuables.

While at at work in Emlagh bog near his home in County Meath, Ireland, peat farmer Jack Conway discovered a 22-pound, roundish mass buried some 16 feet down, reports Smithsonian Magazine.  It turned out that he had come across a 2,000-year-old piece of “bog butter.”

The stuff is exactly what it sounds like: blocks of cow’s-milk butter buried in a bog thousands of years ago, and typically stored in a container of wood or skin. Researchers propose that the blocks were buried there because it protected against spoiling –  with their coolness and lack of oxygen, peat bogs can be nearly as handy as modern appliances.  These conditions allowed the butter to remain more or less preserved, and hidden, over long periods. 

Bog butter might have had mystical purposes as well. A 2010 survey of literature on the religious uses of the butter cites several authors who refer to it as a customary object in thanksgiving rituals, or as a means of inducing the gods’ favor. 

Savina Donohoe, curator of the Cavan County Museum, emphasized the high value of butter at the time in an interview with Fox News, saying it would have been “seen as a luxury.” And she referred to its possible religious significance. “It may have been an offering to the gods,” she said.

People find pieces every few years or so.  In 2009, a 77-pound, 3,000-year-old oak barrel full of butter was discovered, as Smithsonian notes. Four years later, a “turf cutter” – used by peat farmers who cut and sell it as a source of fuel – ran into a 100-pound, 5,000-year-old chunk. 

From 1817 to 1997, 274 findings were reported in total. One researcher writing in 1947 claimed that the practice of depositing chunks of butter in bogs lasted as late as the end of the 18th century, although radiocarbon dating places the practice farther back, between 400 BC and the 13th century AD.

After several thousand years, the chunks more closely resemble cheese in its texture more than the butter consumed now, said Andy Halpin, assistant keeper in the Irish National Museum’s antiquities division, in an interview with the Irish Times.

“Theoretically the stuff is still edible – but we wouldn’t say it’s advisable,” said Mr. Halpin.