"Mummified" trees that lived during Viking times have been discovered near a fjord in southwestern Norway, scientists say.

Dated to the early 1200s, the 40 dead Scotch pines were found scattered among living trees in what was once a dense forest that supplied wood for medieval boats and churches.

The trees appear to have died from natural causes after living out their several-hundred-year life spans.

But somehow the dead trees "survived"—they apparently have never rotted. The mummified trees are different from petrified wood, a kind of fossil created when wood is replaced with minerals over thousands of years.

Tree "Mummies" Astound Researchers

The find astounded researchers, since most dead trees decay as they are eaten by tiny organisms, said research leader Terje Thun, a biologist at the Norwegian University of Science and Technology in Trondheim.

"Here on the west coast of Norway, where it rains a lot and [is] always wet, it was a surprise that the wood was in such good condition," Thun said.

With these uniquely preserved pines, he added, "you could touch the same tree that the Vikings have seen."

Unusually Robust Trees

Thun suspects the trees stayed so fresh for two reasons.

For one, many of the trees had either remained upright or fallen on rocks, avoiding exposure to the wet ground—and thus the water and soil microbes that aid decay.

Also, pines are full of resin, which protects them against wood-eating bacteria. At death, pines release large amounts of resin, which could have helped delay decomposition.

Still, keeping decay at bay for centuries displays unusual hardiness, said Thun, who accidentally found the tree "mummies" while doing research on records of ancient temperatures derived from tree rings.

The Vikings living along the coast of present-day Sogndal in the 12th and 13th centuries apparently favored the robust pines, Thun's study shows.

Timber from a stave church—a distinctive medieval church built by the Vikings—matches wood from the forest that contains the dead trees.

The Norse warriors likely trekked to inland forests to hunt and harvest trees for their buildings, he added.