"If one finds something once, it's accidental. If it is found twice, it's puzzling. If found thrice, there is a pattern," the archaeologists Olle Hemdorff and Eva Thäte say.
In 2005 the archaeologists investigated a grave at Avaldsnes in Karmøy in southwestern Norway, supposed to be from the late Iron Age, i.e. from 600 to 1000 AD. Avaldsnes is rich in archeological finds. They dot an area that has been a seat of power all the way back to around 300. Archaeologist Olle Hemdorff at the University of Stavanger's Museum of Archaeology was responsible for a series of excavations at Avaldsnes in 1993-94 and 2005-06.
"It became clear to us quite early that the grave had been plundered. The material in the grave had been messed up and now contained brick and porcelain fragments from younger layers of soil," Hemdorff says.
Plundering of graves was very common in the 19th century and actually legal. It was not until the Cultural Heritage Act in 1905 made it a criminal offence for lay persons to excavate cultural monuments.
The German archeologist Eva Thäte is in the spring of 2010 visiting researcher at the Archaeological Museum. She is also a guest researcher at the University of Chester in England. The cooperation with Hemdorff started in 2003 when Thäte came to Stavanger in connection with a doctoral work on the recycling of ancient tombs. The latest research project carried out by the two archeologists is on finds of older artifacts in younger graves. In the grave at Avaldsnes the researchers found seven handsome glass pearls in the dirt.
"In the late Iron Age glass was the most common material for making pearls, and therefore glass pearls are often found in men's and women's graves from this period. The women wore the pearls in a cord around the neck and brought more pearls with them into the grave than men did. The discovery of the seven pearls made us assume that it was a woman's grave we investigated," Hemdorff says.
"But then we suddenly found a stone axe. It was in the same layer of soil as some of the pearls. The axe is from the Stone Age and more than a thousand years older than the pearls! It is a so-called greenstone axe. All the other indicators suggested that the cairn was from the Iron Age and belonged to a buried woman. So why was there an old axe from the Stone Age in the grave?," the archaeologists asks.
During the last three years documented discoveries of artifacts have been made that are typical for the Stone Age - marks from flint, flint fragments, quarts, axes, etc. in younger burial mounds.
"Unfortunately this documentation did not begin until the 1970s. Up to that date neither archeologists nor grave robbers were aware of these objects. They were just seen as unimportant and without archaeological value. It is only now that we are beginning to have enough data for analysis, and we have made many enough discoveries of Stone Age artifacts in younger graves to say that they make a clear pattern," Thäte says.
She points to a good example from Sogndal in Sogn og Fjordane where a stone axe was found in an untouched stone coffin from the 5th century.
"The axe must have been placed there intentionally. Other finds in Scandinavia make this pattern even clearer. In Halland in Sweden they have found a burial site consisting of almost one hundred graves from the late Iron Age where one has registered processed flint objects in nearly every grave," Hemdorff says.
Starting with the finds around the grave at Avaldsnes and taking the other finds into account, it is not likely that the axe ended up in the grave by accident. Why was it deposited there?
The researchers say that people back in the Iron Age had a conscious relationship to objects from earlier times that connected them to their past.
"People probably considered old objects as a heritage from their ancestors. Recycling of old burial mounds for new graves is an indication of this relationship. The idea was that the mounds were memories from a distant past, and written sources indicate that recycling of mounds had a double function. Apart from providing a grave for the dead they also legitimized property and rights. People asserted their control over an area by burying their family in a gravesite belonging to their ancestors," Thäte explains.
The archaeologists think that people in pre-history were superstitious and that the axe was deposited in the grave as a part of the burial ritual.
"People believed that the lightning created thunderstones and that individuals who owned such stones would not be hit by the lightening," Hemdorff says.
The idea of a rock falling from the sky caused by lightening is known all over the world. It is certainly found in Roman times and it is connected to objects like meteors, flint stone axes and petrified sea urchins.
"According to folklore a flint axe might protect against lightening and function as a kind of charm," Thäte says.
In Northern Europe the old idea of the thunder god Thor, who throws his hammer when lightning strikes, is common property. It was alive all the way up to the 19th century.
"Thor's mission was to protect gods and people against evil and chaos and it was therefore believed that Thor's rocks protected houses and people. Two things seem to be important when choosing thunderstones: The form had to be similar to an axe or a hammer, that is a ground stone or flint, or the stone had to have "flaming" properties, which flint and quarts have," Hendorff says.
"Both the form of the axe and the flint stones to make fire may be associated with fertility. Thor's hammer is clearly linked to fertility and prosperity. The hammer is a phallus fertilizing the soil, which gives it apotropaic quality, i.e. it has the ability to protect against evil and accidents," Thäte explains.
Since people imagined that thunderstones fell to the ground in connection with lightning, it is possible that the rocks incorporated some of the qualities of lightening or had the power to create a bright light.
"Here is a clear pattern once more. We find old artifacts made of flint in the younger burial mounds. Flint had a strong symbolic power. The stones created fire and were seen as important objects. They can also symbolize the power of lightning", Hemdorff says.
But now back to the axe at Avaldsnes and the question why it was in the plundered grave.
"If you consider how widespread the idea of thunderstones was all the way up to the 19th century, and how common superstition was, it is not unlikely that the grave robbers left a protective amulet to make up for their misdeed. After all they opened a grave and committed sacrilege. Maybe they hoped that the axe provided protection against the spirit of the dead and their ghosts," Hemdorff says.
More excavations of graves and houses with unusual artifacts and comparing them to data from different places will probably yield an even clearer pattern.
Thunderstones are definitely of great archaeological value.