When archaeologist Geir Grønnesby dug test pits at 24 different farms in central Norway, he nearly always found thick layers of fire-cracked stones dating from the Viking Age and earlier. Carbon-14 dating of this evidence tells us that long ago, Norwegians brewed beer using stones.

[…]

In other words, “most of the archaeological information we have about the Viking Age comes from graves, and most of the archaeological information about the Middle Ages comes from excavations in cities,” Grønnesby said. That’s a problem because “most people lived in the countryside.”

Essentially, he says, Norwegian farms are sitting on an enormous underground treasure trove that in places dates from the AD 600, the late Iron Age — and yet they are mostly untouched.

“So I started doing these small excavations to look for cultural layers in farmyards,” he said. “The oldest carbon-14 dates I found are from 600 AD, and all the dates are from this time or later. And when I found the stones, I had to write about them, since there were so many.”

[…]

Grønnesby is not the first to remark on fire-cracked stones on farms in central Norway. That distinction goes to a pioneering sociologist named Eilert Sundt, who recorded an encounter on a farm in 1851 in Hedmark.

As Sundt later wrote, he was walking and saw a farmer near a pile of strange-looking, smallish stones.

“What’s with these stones?” he asked the farmer, pointing to the pile. “They’re brewing stones,” the farmer told him. “Stones they used for cooking to brew beer — from the old days when they didn’t have iron pots.”

In his article, Sundt noted that most of the farms he visited had piles of burned or fire-cracked stones. Every time he asked about them, the answer was the same: they were from brewing, when the stones were heated until they were “glowing hot” and then plopped into wooden vessels to heat things up. The stones were so omnipresent, Sundt wrote, and so thick and compact in places that houses were built right on top of them.

Reports from archaeologists who examined farmsteads in more recent times also confirm this observation. When one archaeologist dug a test trench in the 1980s at a farm in Steinkjer, north of Trondheim, he found a cultural layer more than a metre thick, much of which was fire-cracked stone.

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Grønnesby says the presence of great numbers of brewing stones on Norwegian farms underscores the cultural importance of beer itself.

“Beer drinking was an important part of social and religious institutions,” he said.

For example, the Gulating, a Norwegian parliamentary assembly that met from 900 to 1300 AD, regulated even the smallest details of beer brewing and drinking at that time.

The Gulating’s laws required three farmers to work together to brew beer, which then had to be blessed. An individual who failed to brew beer for three consecutive years had to give half his farm to the bishop and the other half to the King and then leave the country. Only very small farms were exempt from this strict regulation.

What’s equally interesting is when brewing stones disappear from cultural layers — at about 1500, right around the time of the Reformation.

“It could just be a strange coincidence,” Grønnesby said. “It could be religion. Or it could be that iron vessels were more widely available by then.”

…You can read about Grønnesby’s research in the recently published book, “The Agrarian Life of the North: 2000 BC to AD 1000: Studies in Rural Settlement and Farming in Norway”, edited by Frode Iversen & Håkan Petersson. Grønnesby’s chapter is entitled “Hot Rocks! Beer Brewing on Viking and Medieval Age Farms in Trøndelag.”

Fascinating reading! Medievalists Net has the full story.