Rick Farnell says that now he can spot them even while driving down the Alaska Highway. Looking through his windshield, he scans the high ridges above treeline and picks out ice and snow patches with the telltale black line running across them.

The black line signals that the snowfield in question is probably a veritable research lab for scientists from a wide range of disciplines. Most likely archeologists, glaciologists, wildlife biologists and geneticists -- to name a few -- will be interested in that patch of snow and what can be found there.

It's all because the black line shows that the snow patch contains caribou poop, most likely tons of poop, so much of it that the older feces are compressed into a thick layer that can be spotted from far away.

More importantly, this is ancient dung, some as much as 8,000 years old. Artifacts of almost equal antiquity have been found on and around the snowfields, left there by the people who once hunted the caribou. Remains of bison, sheep, and other animals have been found, and almost all of these artifacts have been beautifully preserved in the ice on the high cold ridges.

Farnell, a caribou biologist with the Yukon Department of Renewable Resources, coordinates the various research projects associated with the ice patches. So far 70 to 80 sites have been identified in the southern Yukon, with most of them on the lee side of the Coast Range.

But as obvious as this treasure trove of information appears now, no one had any idea of the secrets contained in these ice patches until a few years ago.

"The whole thing started when my colleague Gerry Kuzyk was out on a tramp," says Farnell. In 1997, Kuzyk came across an icefield in the Kusawa Lake area that was thickly covered with caribou dung.

Caribou gather on ice patches in the summer to get away from biting insects. But they usually only spend a few hours there at a time, and there are not enough caribou in all of the southern Yukon today to produce the huge quantities of feces that Kuzyk was seeing.

Knowing that something unusual was going on, Kuzyk brought other experts to the site. One of the first visitors found an atlatl shaft lying on the ground that has been dated at 3,510 years of age. This ancient spear-thrower is considered to be a world-class archeological find.

This site is now known as Thandlat, which means "sharp-pointed mountain" in Southern Tutchone. The sites are in the traditional territories of three First Nations, and the artifacts melting out of the alpine ice are striking a chord in their communities.

The findings tie into their oral traditions about caribou, and the important role they have played in their culture. The First Nations are coordinating their own research projects, and using the finds as a way to generate an interest in science among youth in their communities.

Their projects will join those of a wide array of other researchers. At the Ancient Molecules Center at England's Oxford University, researchers are doing genetic work on various caribou remains. Farnell is quite excited about how their findings could help with his own research on genotyping modern caribou herds in the Yukon.

Once they establish whether these ancient caribou were from woodland or barrenground herds, they can start to look at how the caribou evolved over time. That information could help with modern management decisions, as some woodland herds in the Yukon are now in serious decline.

Farnell says that once they are able to take a longer view of caribou as a species, they might find that individual herds have often ebbed and flowed over time, dying out in one place only to recolonize in another.

"Caribou are a very flexible species in that they have coexisted with a lot of other species that do not exist today. They pushed through the big Ice Age extinction without any problem, so they are a great species to look at in terms of long range evolution," he says.

The contaminants unit with the Department of Indian Affairs and Northern Development is analyzing some of the caribou teeth that have been found. The researchers are trying to determine whether some contaminants, such as mercury, might always have been present in northern ecosystems.

Other researchers are picking through the ancient turds to find parasites and pollen. The discovery of a giardia cyst in one 5,000-year-old pellet proves that this parasite has been around for a very long time in North America, and was not introduced by Europeans when they arrived on the continent.

Pollen grains found in the feces can show how alpine plant communities have changed over time, and whether the diet of the caribou might have changed as well.

Eric Blake, a Yukon-based glaciologist, is one of the researchers using the ice patches to study climate change. The sites are nicely layered, with older poop at the bottom and the newer stuff on top. The age of the feces can be determined through carbon-dating, which also shows the age of the snow layer in which the feces were found.

Blake finds the telltale black band in the ice patches particularly interesting, since it could indicate a warm period that melted many of the snow layers and consolidated the dung.

"We're thinking that there might be 5,000 years worth of poop in that layer," says Blake.

For Farnell, the research opportunities connected to this site are just beginning to be tapped. In a large walk-in freezer at the Renewable Resources building, he has numerous boxes of ancient caribou dung in storage and thinks the interest in them will spread among scientists.

"We're starting a whole new field of research here," says Farnell. "It is just amazing what you can learn from caribou turds."

Rick Farnell can be contacted at rick.farnell@gov.yk.ca. For more information on ice patch research, check yourYukon column 199 and column 200.