Biologist Gerry Kuzyk was hiking with his wife in the remote reaches of the Yukon when he caught the putrid scent of caribou dung wafting through the chill air. Then he saw it -- the biggest pile of animal droppings he had ever seen, 8 feet high and stretching over half a mile of mountainside.
Kuzyk, a researcher with the Yukon Department of Renewable Resources, knew there weren't enough caribou in the entire territory to create such an epic mound. Odder yet, there hadn't been caribou in the area for nearly a century.
"It was like being in the 'Twilight Zone,' " said Rick Farnell, a colleague who helped investigate the find. "You could see them from a distance -- big, black bands of feces. I'm talking tons of it."
The mystery was solved by lab analysis: The dung, the product of innumerable migrating caribou herds, had been frozen for thousands of years and only recently exposed by melting ice. Along with the dung, the scientists soon discovered an arsenal of Stone Age darts, arrows and spears.
The artifacts are just part of a trove of ancient artifacts, animal carcasses and human remains being disgorged by vanishing glaciers and ice patches across the globe as the planet's temperature gradually increases.
"It's like an Easter egg hunt," said Greg Hare, an archeologist with the Yukon Heritage Branch.
For most scientists, from ecologists to climate experts, the warming of the planet is a disturbing trend that could radically alter the environment. But for archeologists, it has prompted a breathtaking treasure hunt.
Without doing any digging, the scientists are scooping up artifacts, mummies and fossils long hidden in the depths of monstrous glaciers.
"We walk right up and pull arrows and animals out of the ice," Farnell said.
Many of the items are simply the random debris of 10,000 years of passing human and animal traffic. But the glaciers also have coughed up some stunning finds. In 1991, Swiss hikers in the Alps found "Otzi," a 5,300-year-old ice man felled by a flint arrowhead. A second ice man with a perfectly preserved woven hat and gopher-skin cloak melted out of the ice in British Columbia in 1999.
A year earlier, a glacier in the Chilean Andes disgorged the Rolls-Royce engine of a British airliner named Stardust that had been lost since it crashed in 1947.
"It's incredible what's in the ice," said E. James Dixon, an archeologist at the University of Colorado's Institute of Arctic and Alpine Research.
Piece by piece, the artifacts rising from the ancient ice are beginning to recast archeologists' understanding of the thousands of years after the last great Ice Age, an epoch when animals began probing the northern fringes of the planet and bands of humans began to populate North America in large numbers.
"There's a whole new scientific window opening," said Dixon, an expert on the human colonization of North America.
Unlike buried dinosaur fossils or crumbling Mayan monuments, the glacier artifacts are relatively unchanged from the day they were first encased in their icy tombs. They have given scientists a glimpse of the past, frozen in icy perfection.
Arctic lupine seeds frozen for 10,000 years, for example, grew into healthy plants once they were removed from Ice Age lemming burrows. The ice holds a zoo of perfectly mummified animals: fish, wapiti, sheep, mountain goats, moose, voles and birds.
"They're so beautifully preserved, they look like they're asleep," Farnell said. "You can't tell whether they died last week or died 4,000 years ago."
For archeologists used to piecing together the past from chips of flint, finding soft organic material is rare bounty. They have flesh filled with DNA, feathers and dustings of ancient pollen. There are stomachs filled with the remnants of a last meal and patchworks of human tattoos.
Unbroken arrows sport intact feathers. Darts colored by red ochre have soft, sinew lashings. One stone knife found in the Yukon sports caribou hairs. Another has bloodstains. "It actually killed something," Farnell said.
The part of glaciers that are now melting captured a very particular slice of history -- a roughly 10,000-year period from the end of the last great Ice Age to the present. The period began when the forbidding sheets of ice that had covered much of the Northern Hemisphere were beginning to retreat, opening a new realm of the planet to animals, birds and waves of human wanderers that eventually found their way to the Americas.
Over the ensuing years, the glaciers ebbed and flowed, driven by vast, cyclical changes in weather that could send tongues of ice rushing downward, only to retreat to alpine refuges a few hundred years later. The last one, known as the Little Ice Age, began about 1450 and only completed its cycle about 1900.
The planet is now in the midst of a natural warming cycle that has been compounded by a modern infusion of greenhouse gases -- carbon dioxide and other gases that are byproducts of industrialization. The result is a galloping recession of ice that has not just sprinkled these treasures of history on the landscape, but spewed them, heaping era after era into one big pile.
Lying next to 6,800-year-old stone points are 3,500-year-old dart hurlers and 6-foot spears. Animals dead for just a few years lie next to 3,000-year-old carcasses. One of the best-known discoveries is the frozen mummy found in the Alps in 1991. Named Otzi after Italy's Otztal Alps, the ice man was found by two hikers who spotted the corpse embedded in the melting Schnalstal glacier.
Otzi had straw shoes, a leather coat with goat fur, a copper ax, a stone dagger and a bow. He was so well preserved that scientists were able to determine his last meal (some bread made of einkorn wheat and meat) and conclude that he journeyed into the mountains between March and June (the pollen in his stomach come from a tree that only blooms then).
No one is certain why Otzi was in the mountains, although researchers this year discovered that he died in a violent hand-to-hand battle after finding a deep knife gash on his right hand. Scientists found an arrowhead and an open wound in his left shoulder the year before.
The presence of Otzi and other human artifacts has surprised scientists like Dixon, who had no idea that so much human activity took place on these forbidding fields of ice.
In 1999, a trio of sheep hunters at the edge of a glacier in northwestern British Columbia found a piece of wood on the ground, an unusual sight in that barren area above the tree line. It turned out to be part of a carved walking stick.
Further exploration turned up the corpse of the unfortunate "Kwaday Dan Sinchi," or "long ago person found." Radiocarbon dating showed the twenty-something man had lived in the 1400s, decades before Columbus reached the New World. Found with the body were a carefully woven waterproof hat, a gopher-skin cloak and a leather pouch filled with snacks of plants and fish.
The discovery confirmed the oral traditions of the local Champagne and Aishihik First Nations, which describe the glaciers as trade routes to the coast.
"There are a lot of stories about the glaciers and people traveling back and forth," said Diane Strand, the tribe's heritage resource officer. "And there are stories about people who never came back."
Tools found near Kwaday Dan Sinchi were made from both coastal and interior trees. The gopher cloak came from the interior while the cedar and spruce root hat was in the coastal style. Modern tribal weavers had never seen the hat pattern before but are now re-creating it to preserve history and reuse its excellent design, Strand said.
It's only one of the many tantalizing bits of information that have begun to emerge from the disappearing ice.
The discoveries have answered a simmering debate in North American archeology over when bow-and-arrow technology took hold. Some experts argued that bow and arrows existed for thousands of years alongside the earlier dart-throwing weapons known as atlatls. It had been difficult to trace the development of the technology with only stone tips that could have come from either type of weapon.
"Here, we've got the whole projectile system," Hare said. The many weapons discovered in the Yukon show that the atlatl was key from 7,300 to 1,200 years ago. The bow and arrow showed up 1,200 years ago and then dominates, Hare said.
Melting ice in the Yukon and also in the Colorado Rockies has revealed bison carcasses in high mountain regions, suggesting that these herbivores of the Plains roamed farther and higher than previously thought. A Giardia lamblia cyst in one 5,000-year-old caribou dung pellet has conclusively shown that the intestinal bug was a long-standing pest in North America and not brought over by European explorers as some had believed.
Genetic analysis of caribou remains found amid the Yukon dung heap is revealing the dynamics of these ancient herds and helping find ways to preserve their endangered modern kin.
There is a dark side as well. In 1988, medical archeologist Peter Lewin went to Norway's Spitsbergen archipelago in the Arctic Ocean to help exhume and study victims of the great 1918 flu epidemic that were buried in permafrost. While he found no live, infectious virus, he fears that victims of flu and even smallpox now being pushed to the surface by thawing permafrost in Arctic cemeteries could still be contagious.
He also fears the emergence of chemical, nuclear and biological contaminants buried in Siberia from dumps now exposed by warmth to scavenging. "The old Soviet Union thought the cold would last forever," he said.
The warming is expected to continue and perhaps accelerate. While melting ice exposes items for archeologists, it also removes the frozen protection that has kept artifacts and bodies in such good condition. Without its blanket of ice, organic material decays and disappears.
Ravens feast on the newly thawed carcasses. Objects rot in the open air and rodents gnaw on ancient bones.
Dixon and geologist William Manley of the Institute of Arctic and Alpine Research developed a computerized mapping system to help them locate the most promising areas for collecting.
Manley, an expert in past climates, layered a series of maps together, looking for areas where glacial melting coincided with good hunting grounds, mineral licks or rock-collecting sites that may have drawn ancient people. "Rather than rely on serendipitous discovery, we wanted to hone in on the most productive areas," Manley said.
They tested the model in Wrangell-St. Elias National Park and Preserve in southeast Alaska in 2001. Manley and Dixon selected the 32 best areas and leapfrogged from one to another by helicopter, hopping out onto the ice to pluck up an archeological potpourri.
The finds included an antler-tipped weapon lying next to a punctured caribou scapula, a series of freeze-dried vole mummies, a scattering of bird bones, handfuls of horse hoof trimmings from Gold Rush days and, dozens of miles from the coast, one perfectly preserved fish. They resume the hunt this summer.
"If we don't get to the material in a year, or even a month, it might be gone," Dixon said.