Researchers say they have found a 10,000-year-old wooden hunting weapon similar to a spear melting out of an ice patch near Yellowstone National Park.

The birch sapling dart was discovered high in the Rocky Mountains, and was announced by the University of Colorado.

The 91-centimetre weapon, which looks like a small bent branch and still bears the personal markings of the ancient hunter who used it, likely had a projectile point on one end, according to the researchers. On the other end, a cup or dimple would have attached to an atlatl, a 61-centimetre throwing tool about .61 metre in order to obtain greater velocity.

"We didn't realise until the early 2000s that there was a potential to find archaeological materials in association with melting permanent snow and ice in many areas of the globe," said University of Colorado at Boulder Research Associate Craig Lee, who made the finding.

"We're not talking about massive glaciers, we're talking about the smaller, more kinetically stable snowbanks that you might see if you go to Rocky Mountain National Park," added Lee, a specialist in the emerging field of ice patch archaeology.

He said the dart had likely been preserved in ice for 10 millennia and that global warming was accelerating the melting of permanent ice fields, thus exposing long-preserved materials.

Perennial snow, glaciers and ice fields cover about 10 percent of the planet's land surface, according to Lee, who noted that organic artifacts can be lost forever once they are no longer entombed in the ice.