Archaeologists working with Norway’s Secrets of the Ice program recently got a shock when a arrow shaft they had previously dated to the Iron Age turned out to be some 4,000 years old.

The scientists had collected the arrow from the side of a mountain, Lauvhøe, and at first, it looked like other Iron Age arrows collected from the area. But after the researchers cleaned the glacial silt off one end, they found a notch befitting a stone arrowhead and not an iron one. The team co-directed by Lars Holger Pilø – an archaeologist with the local Department of Cultural Heritage – concluded that the arrow dated to the Stone Age, pending radiocarbon dating.

Whatever the results, the arrow joins a wealth recovered by Secrets of the Ice, which has recovered examples from as early as 6,000 years ago from the melting ice of Norway, according to secretsoftheice.com.

What Is Glacial Archaeology?

Climate change has nonetheless led to a renaissance in the mini-field of glacial archaeology, which is something of a misnomer. For its part, Secrets of the Ice prefers to work on and around ice patches that move little instead of glaciers, which contain relatively young ice and grind up artifacts. Pilø and others pore over maps and geographical databases to find the best spots and sometimes take to the air in helicopters.

Once they have decided on a location, they hike up to it and camp sometimes for weeks on end while scouring the margins where the ice has just melted. They slowly patrol up and down the ribbon of bare rock where the surrounding lichen has yet to rebound (a process that takes hundreds of years), looking for what the ice has just released. Their recent discoveries include a worn knife blade, a snowshoe for a horse and a rare arrow made with a freshwater pearl mussel.

“Such shell arrowheads are only known in Norway and in northwest America,” said Pilø.

Read More: How Archaeologists Know Where to Dig

Norway’s Ancient Hunting Grounds

Secrets of the Ice has discovered many hunting artifacts as the Norwegian ice once served as a major hunting ground for reindeer during the summer. Then, the animals sought to escape swarms of parasitic botflies at lower altitudes but instead ran into the arrows of humans, who herded them using wooden “scaring sticks.” Archaeologists have recovered many of the sticks, which held an object that moved in the wind and startled the animals into the range of human bows.

Innlandet County remains the center of Norwegian glacial archaeology, and Secrets of the Ice claims to have made more than 3,700 finds there across some 65 sites. Scientists have also practiced the field in Western Canada, the Rocky Mountains and Alaska, where higher-than-average temperatures have worn away the ice.

Part of the Norway Department of Cultural Heritage, Secrets of the Ice stands as the most prominent effort, with roots extending to a dramatic melting in 2006 that revealed, among other things, an Early Bronze Age shoe. The group has also discovered hundreds of Viking artifacts, particularly in the Lendbreen pass, a ridge where the people had traveled and stacked rock cairns to mark the way.

Read More: Study Shows Changing Glaciers Could Impact Wildlife and Tourism at National Parks