Glaciers and ice patches can sometimes hold remains for thousands of years in deep freeze, preserving even delicate materials such as feathers, skin, or sinew—materials that rarely stand the test of time. Ancient arrows, clothing, toys, or even an entire mummified human body may rest in eternal limbo. In a way, it’s an archaeologist’s dream.
“That’s the craziest thing about it—it’s actually a giant prehistoric deep-freeze freezer,” says Lars Piljo, co-director of Secrets of the Ice, the glacial archeology program of Innlandet, a Norwegian county. “Usually when we find things, you can see they’re old. But some of these artifacts are not truly obsolete.
But with some glaciers and ice patches now melting at unprecedented rates due to climate change, these ancient time capsules are thawing for the first time in millennia. As a result, archaeologists are struggling to keep up with the abundance of information that may soon begin to deteriorate as it is once again exposed to the elements.
The ice one is coming
When tourists discovered Iozzi the Iceman in 1991 on a glacier near the Austrian-Italian border, they had no idea how old the mummy was. The 5,300-year-old mummy juts out of the Similaun Glacier in the Ötztal Alps, after which it is named.
The preservation of a naturally mummified man of this age and in a condition apparently close to the way he was when he died is an unprecedented discovery.
“Ötzi is the Holy Grail,” says Pilø.
The body was so well preserved that researchers have extracted a wealth of information from this single body, frozen for millennia. The arrowhead still embedded in his back probably killed him. Before his death, scholars believe he needed a dentist, and he may have had stomach problemsbased on his last meals found in his intestines. Some of the tattoos still found on his body, may represent a form of treatment similar to acupuncture, according to some research.
Even Iceman’s clothes were preserved, and his complete genome sequenced.
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Ancient reindeer hunting
In Innlandet county, where Pilø works, there was a spike in artifacts about 15 years ago when there was a major meltdown in the area. “In 2006, we had a big shell strike because there were so many artifacts coming out of the ice,” Pillo says.
Ice patches have revealed many materials related to ancient reindeer hunting, some dating back 6,000 years.
The way the artifacts are scattered reveals how this hunt is going. The researchers found arrows and several one-meter stakes, which archaeologists determined were used to guide groups of reindeer to waiting hunters. But these kinds of discoveries can also illustrate some of the limitations of glacial archaeology.
While frozen artifacts may be particularly well preserved, glaciers are not static blocks of ice. They move like slow rivers, carrying whatever is buried inside with them and often destroying artifacts in the process. Artifacts covered by ice centuries earlier could travel some distance before being pushed to the edge of the glacier, where the ice normally melts.
Because of their movement, most glaciers will not retain artifacts for more than 500 years. And when artifacts are found in these regions, they have often been moved from where they started. Many other artifacts are embedded in patches of ice that don’t move as much, if at all. However, accidental melting of the surface can cause artifacts to be washed downstream.
Some of the best information coming from glaciers and ice sheets, Pillo says, is stored in mountain passes. These were places that often saw human travelers – Ötzi was discovered in a mountain pass, for example. These passes also have a wide variety of different types of sites compared to hunting grounds elsewhere. In 2011, when another major meltdown occurred in Norway’s Lendbreen Pass, Pilø’s work revealed a 4,400-year-old arrowhead with a blunt end. It was so small that it couldn’t pierce anything if it was loaded on a bow. The researchers determined that it must be a toy.
Researchers can learn a lot from the arrows because the preserved material reveals what materials were used to make them. They can learn what birds were used for the feathers, for example, and what kind of wood, which reveals how hunting societies used the materials.
The Landbreen Pass has revealed thousands of artifacts. Pilø says archaeologists often explore the ice as a team, walking close to each other along the edge of the melt, trying to spot sometimes infinitesimal artifacts. In 2011, archaeologists discovered a preserved glove with a glove dating from the 9th century, a full woolen tunic and leather shoes. In 2019, they discovered remains of a domestic dog still attached to collar and leash.
Glacier archeology grew out of just a small group of dedicated people, Pillo says. When the big melt happened in 2006, archaeologists in Norway were not prepared for it – there was no special program to deal with the melting of glaciers and ice patches. But Secrets of the Ice was established in 2011 with ongoing funding from the Norwegian government and Inlandet County Council.
Meanwhile, researchers elsewhere have made other amazing discoveries. In Rocky Mountain National Park they find an atlatla type of device used to throw spears and dates back 10,000 years.
“[Glacier archaeology] now it has become a worldwide phenomenon,” says Pillo.