Digging for the truth about the Kensington Runestone with Artec Eva and Space Spider
For more than a century now, historians and scientists have argued over when Vikings first came to America, and how far west they traveled. One of the key artifacts in this debate has been the Kensington Runestone, a 202-pound (92 kilos) stone unearthed by a Minnesota farmer in 1898. Carved with seemingly-ancient Scandinavian runes, if proven to be authentic, this artifact could change American history as we know it.
Two popular archaeologists, Blue Nelson and Mike Arbuthnot, hosts of the hit TV show America’s Lost Vikings, decided to take a closer look.
“Since the Runestone was first discovered in 1898, scientists have been divided over whether the carvings are actually 650 years old,” said Nelson.
Vikings are known to have crossed the Atlantic and settled, at least for a time, on the coast of Newfoundland, at L'Anse aux Meadows, around the year 1000. But the distance from there to Kensington, Minnesota, where the runestone was found tangled up in the roots of an aspen tree, is another 1,800 miles away. If and how the Vikings actually went that far is another question altogether.
Critics of the Runestone suggest that it was Olof Ohman, the Minnesota farmer who found the Runestone, who actually carved and then buried it, hoping to fool everyone into believing his counterfeit was the real deal.
The Runestone consists of two different kinds of stone, a harder mineral, greywacke, and a softer one, white calcite. Blue Nelson’s first reaction upon taking a closer look at the stone was that because the stone was found lying face down in damp soil, and had been there for more than six centuries, the runes carved into the softer calcite should show far more weathering than those chiseled into the greywacke stone.
But just looking at the stone with a small magnifying glass wasn’t going to give them any answers. They needed to accurately measure the precise depth and shapes of the carvings in high detail, so there would be no doubt remaining. That’s when they turned to 3D scanning.
3D scanning has proven itself time after time in the field of archaeology. Not only does it let us look deeper and far more clearly into artifacts and their intricate details, but because everything is being captured digitally and turned into highly dynamic 3D models, archaeologists are also able to share digital copies of these same artifacts, archive them for future research, and 3D print them in a variety of materials, even printing miniature or enlarged versions of the original.
The specialists at Laser Design were called in to provide their expert help with the scanning, bringing with them the handheld color 3D scanners Artec Eva and Artec Space Spider. The Kensington Runestone had been scanned in 3D in the past, but with nothing even close to the level of detail that Artec’s scanners bring. Eva boasts a point accuracy of up to .1 mm, while Space Spider delivers a breathtaking .05mm.
Kevin Shain of Laser Design assisted with the scanning, giving both Nelson and Arbuthnot a 10-minute crash course on how to scan. That was enough to get them up and going. Just a few minutes in, and they were already scanning like old pros.
“Artec scanners are the easiest that I’ve ever trained with, and new users of all skill levels are able to understand what to do and why very quickly,” said Shain.
“This is incredible…” said Nelson, “…totally non-invasive.” “This will be the highest resolution 3D model of the Kensington Runestone ever produced.”
As they scanned the Runestone, they watched the extremely detailed color images of the ancient runes come to life on the screen in real time.
The entire scan was completed in less than one hour. First, Eva was used for overall coverage and color detail of the stone. Then, to ensure the maximum level of detail, Space Spider was used on the individual runes themselves. Even though Space Spider is normally used for smaller objects, the Runestone’s large size (30 × 16 × 6 inches (76 × 41 × 15 cm)) was not a problem for the handheld scanner, which, together with the scan from Eva, easily captured all the data in under an hour.
“The amount of detail you got with that thing is incredible,” said Nelson, looking at the preview.
Post-processing of the scans was done in Artec Studio and took less than one hour for the initial color results. The final high resolution scans were completed in four hours, with the extra time taken to ensure that the 3D model was a seamless, perfect digital copy of the Kensington Runestone.
In the words of Laser Design’s 3D scanning expert Kevin Shain, here’s how the post processing was done: “Having only one day with the Runestone, I needed to work fast and accurately. After scanning, I aligned the Eva datasets together, did some outlier removal, then finished with sharp fusion. Next, I combined the data with the super high resolution Space Spider data.”
“The Space Spider and EVA data completely matched. I ran the last global registration on everything, followed by an outlier removal, and finally sharp fusion. The result was a complete, high resolution 3D model of the Kensington Runestone.”
Once they had the model in hand, the archaeologists performed a cross-sectional examination of the individual runes, comparing those in the soft calcite to the same letters carved in the hard greywacke.
They chose the letter V to focus on. In the soft calcite, the weathering was so significant that the letter appeared to be more like a U. And the calcite runes overall were 25% shallower than those in the greywacke.
“25% is what you would expect over about 130 years of wear,” said Blue Nelson, expressing his doubt that the stone had actually been lying face down in damp soil for the past 650 years.
But Mike Arbuthnot had his own ideas, “How do you know what the level of weathering would be over 125 years? Let’s assume that the story is real.”
So they agreed to disagree. Even though thanks to 3D scanning, the contrast between the Runestone carvings was crystal clear, it still didn’t solve the mystery. Further evidence was needed.
The rest of the episode is dedicated to their searching for that very evidence, as they recreate part of the supposed journey of the Vikings in Minnesota by rowing a small replica Viking boat in winter up the St. Louis River, as well as pay a visit an expert stone carver, to see if it would be possible for an everyday person to carve a similar runestone.
To learn more, tune in to watch the show here:
(episode 4, Ghosts of the Great Lakes)