The Viking Great Army may have finally been found.
A mass grave discovered in England in the 1980s was initially thought to be associated with the Vikings, but radiocarbon dating suggested that the skeletons belonged to different time periods.
A new study says that an unlikely culprit confused the radiocarbon dating: fish consumed by the Vikings. Eating fish and other marine life results in older carbon in our bones than land-based food sources, throwing off carbon dating.
The new calibration used by the researchers, accounting for this "marine reservoir effect," has confirmed that all of the bones date to the same time period from the ninth century. The results were published in the journal Antiquity on Friday.
Confirming the dates provides new evidence about the activities of the Viking Great Army in England and greater understanding of the impact of the Vikings in central England, as well as how important it is for researchers to use the latest techniques.
The site, at St. Wystan's Church in Repton, Derbyshire, includes a double grave containing two men, a grave containing four adolescents between the ages of 8 and 18 and a large burial mound covering a charnel -- a vault containing skeletal remains -- that includes the bones of nearly 300 people.
"The discoveries at Repton are extremely rare: despite significant historical information about the early Viking raids in England, we actually know very little about the actual people involved," Cat Jarman, study author and Ph.D. student in the University of Bristol's Department of Archaeology and Anthropology, wrote in an email. "There are very few known Viking graves in England and no others that can be securely connected to the Viking Great Army."
History says the Viking Great Army wintered at Repton in 873, driving the Anglo-Saxon Mercian King Burghred into exile in Paris.
"It seems likely that the Great Army attacked the Anglo-Saxon monastery and used the site as a winter camp," Jarman said. "It is thought to have been a wealthy monastery with royal connections, and there was a practical reason for overwintering there too: it was likely to have held considerable food supplies to feed a hungry army."
But the Vikings also wanted to make a power move, rife with politics.
"It was also the burial place of several Mercian (Anglo-Saxon) royals, so this was a political statement as well," Jarman said. "The original excavations also found evidence for fortifications. At some point, possibly towards the end of the winter before the army moved on, the building in the vicarage garden was turned into a burial chamber and the bones were moved the eastern compartment. A mound was then built on top and the whole charnel turned into a burial monument - desecrating what was probably an important Anglo-Saxon building, possibly a mausoleum. This was a very deliberate statement and expression of power on the Vikings' part."
Though common in Scandinavia, these double graves are more rare in England. The two men were buried next to what is thought to have been the burial place of the Anglo-Saxon kings, suggesting their importance. They might have been leaders of the Great Army. The double grave was covered in stones, fragments of a finely carved Anglo-Saxon cross that had been destroyed, Jarman said.
The double grave also held some interesting artifacts. The older of the two men was buried with a necklace bearing Thor's hammer and a Viking sword. The evidence of fatal injuries mark his bones, including a large cut to his left femur. It's possible that the injury severed his penis or testicles; a boar's tusk was placed between his legs, and the researchers believe that the tusk was meant to replace what he lost and prepare him for the afterlife.
Dating the charnel and double grave to the same time, and linking them to the Vikings with the help of artifacts, shapes a story around Repton and what happened there in the ninth century.
The juvenile grave, which included a sheep's jaw buried at the children's feet, is believed to be a ritual killing that occurred to mark the creation of the new burial mound, Jarman said. Large stones next to the mound appear to have held some type of marker. Two of the skeletons bear signs of traumatic injury. This further suggests that the deaths of the children were ritualistic, meant to accompany the dead Vikings in the afterlife. This matches with historical accounts throughout the Viking age.
And if the charnel does belong to the Great Army, it tells a new story.
"It's a really exciting opportunity to understand more about how such a group was made up," Jarman said. "Where sex could be determined, around 20% were women, and this is in contrast to previous assumptions that the Viking raiders were solely male. Of course, we can't know if these women (or men, for that matter) were 'warriors' but it demonstrates that the group was made up of both genders. We can also learn more about their geographical origins. My own research on these Repton remains has so far shown that this group was made up of people with mixed origins -- and this seems consistent with historical sources we have about the period as well."
Eighty percent of the remains were male, between the ages of 18 and 45. Many of them bear the marks of violent injury.
Jarman and her colleagues believe that calibrations for the marine reservoir effect need to be an essential part of the archaeologists' toolkit and should be applied to all radiocarbon dates of human remains. This is especially important for any communities in which fish were part of the diet. Jarman also said that previously dated sites should be given a second look, as this could lead to the discovery of more sites like Repton.
Over the past two years, Jarman has co-directed more excavations at Repton to learn more about this winter camp for the Vikings. Her team's research has shown that the camp was much larger than previously thought.
This year, they will be able to share more about the geographical origins of the people buried at the Repton site, as well as the findings from ancient DNA they were able to extract from the skeletons.
"I'm also very interested to find out what happened next," Jarman said. "Only a few years later, we know that a large part of the army divided out land and settled in England. Who were these people and where did they settle? How did they interact with the local, Anglo-Saxon population? This was a crucial period in the history of England that had a vast impact on economic and political development, culture, language and even the development of towns, but there is still a lot we don't know."
A previously excavated grave site has been dated to the Viking age
The site includes what may be the remains of the Viking Great Army