How Do Artifacts Become Trapped in Ice Patches?
Ice patches are accumulations of windblown snow in alpine and subalpine areas that have existed for thousands of years. Large animals such as sheep, bison and elk go to these locations to cool off and escape biting insects in the warm summer months, as well as to access running water and enhanced foraging opportunities. This predictable behavior was targeted by ancient hunters searching for game. For thousands of years, anything left behind on one of these patches could become encased and frozen — animal bones, tools, a fragment of basket, a digging stick, the shaft of an ancient spearthrower. Some of the tools are otherwise rarely preserved in the archeological record.

You can watch an animation of this process and how ice patches are now melting, exposing their contents. Just click on the animation button at right.
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ANIMATION

View an animation showing how artifacts become trapped in ice and then discovered. Click on the image to view the animation.

What's Been Found in Glacier National Park?
GLAC 16-4, metapodial
Higher temperatures not only endanger ice patches, they also threaten the delicate contents within. Shorter, warmer winters with winter rainfall events erode ice patches quickly, exposing artifacts and ancient biological materials. Once organic items become exposed, there is a short window of time before their irrevocable loss. If exposed items are not removed by animals or stolen or disturbed by park visitors, then they will deterioriate: an arrow's fletching, for example, becomes detached within a year of exposure, sinew shortly thereafter. According to ice patch archeologist Craig Lee, wood deteriorates in four or five years, and bone or antler within 10 years.

Because the NPS is charged with stewardship of the material traces of our natural and cultural heritage, it is our responsibility to minimize the loss of these items. And because parks are ideal places to learn about natural and cultural systems in a relatively non-disrupted state, we have a clear opportunity and mission to work with specialists in many fields. Native American communities and traditional experts, scientists, and agency managers all have a stake in protecting and learning from the emerging contents of ice patches.

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3-D Bison Skull

View a 3-D rotation of a bison skull discovered in one of Glacier Park's ice patches. Click on the image to view the skull in 3-D

In Glacier National Park no human-made artifacts have yet been found associated with ice patches. But an array of paleo-biological discoveries have enormous potential to inform our understanding about climates and ecosystems of Glacier’s ancient past, as well as the ways that these systems transformed over time. A cranial and post-cranial pieces from a male bison were found at an ice patch in 2012. This skull and the other bison bones found with it are the first confirmed material evidence of bison in the high mountains of Glacier National Park. A sample of one of the bison bones dates to 967 BP. Click the image at right to view it or click on the tabs below to learn more.
Click on the three tabs below to learn more about materials found in Glacier Park's ice patches:
Wood
A variety of trees are represented by wood fragments found in or near Glacier’s ice patches. Collected specimens include yew, western larch, Douglas fir, and pine (possibly white pine). Radiocarbon dates vary widely from 160 +/- 40 BP to 5300 +/- 40 BP (both yew specimens). A cluster of dates in the 900-1300 BP range include the Douglas fir, larch, and pine species as well as yew. Wood can be deposited in a number of ways, including transport by large raptors for nesting material. If the fragments were transported then they are less likely to be indicators that trees once stood in these locations. The team evaluated known golden eagle nest locations using Glacier NP data, and none of the currently known nests is near any ice patch that yielded wood fragments. Also, the team is documenting whether fragments are ‘rooted’, which is a better indicator that the tree actually grew nearby. More wood samples are currently under analysis.
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Bone
In 2012 a high-elevation ice patch forefield yielded a number of animal bones. The bones showed no signs of human modification and were likely deposited when the animals died naturally, probably upslope of their current location. Most bones were from mountain goat and bighorn sheep, but an unusual and interesting discovery was the well-preserved cranium and several limb, rib, and vertebral elements of an adult male bison. This is the first confirmed material evidence of bison in the high mountains of Glacier National Park. A sample of the bison bone dates to 967 ± 15 BP and a d13C value of -18.3 are suggestive of a primarily C3 diet from high country plants. This could indicate this bison was a frequent visitor to the high country.
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Organic Layers
The Glacier Ice Patch team has pioneered, with the assistance of the U.S. Ice Drilling Design and Operations Program at the University of Wisconsin-Madison, a new technique for obtaining cores from the unusually porous ice found in subalpine patches. In 2013 the team collected several samples from an ice patch near Siyeh Pass. Thin dark layers of organic matter composed of windblown dust, animal feces, and possibly volcanic ash, are indicative of warming periods when melting layers ‘lagged’ or collapsed on top of each other. The dark layers were sampled by documented, melting, straining through fine mesh, and packaging in the field. Results identifying the composition of the organics and their age are pending.
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