Eight-Foot-Long Beavers, Scimitar Cats, and Woolly Mammoths

What the Past Tells Us about the Future Arctic

At Ballast Brook, on the north end of Banks Island in the Canadian Arctic Archipelago, the trunk of a spruce tree emerges from the eroding permafrost. Although it looks as if this tree might have died only two or three years ago, it has been entombed in an icy grave of peat and gravel for the past three million to five million years. This tree is a remnant of a boreal forest that once covered this stark tundra landscape.

In the summer of 1967, geologist Len Hills was hiking along this plateau at Ballast Brook when he spotted a large, fossilized bone protruding from the surface not far from that tree. It was cold, wet, and snowing at the time. Hills picked up the specimen, put it in his bag, and carried on without really knowing what he had found that day. Being a palynologist, he was more interested in finding the spores and pollen from the ancient plants that once grew here than what might have walked on four legs.

Hills didn't give the discovery another thought until Dale Russell, a paleontologist with the Canadian Museum of Nature, telephoned him some ten years later and asked whether he had ever come across some Cretaceous-era bones during his explorations in the High Arctic.

Hills thought it an odd request. At the time, very few scientists seriously considered the possibility that Tyrannosaurus rex and other dinosaurs had ever ventured anywhere near the polar world. It had never occurred to him that one or more of the unidentified fossils he had picked up during his many research expeditions to the Arctic could be that of a "terrible lizard."

Back in his lab, Hills searched for, and found, the fossil he had picked up at Ballast Brook that day. He gave it a wash and then had a good laugh when he and his colleagues finally figured out what it was. The fossil was not that of a dinosaur; rather, it was the shinbone of a woolly mammoth, a giant elephant-like animal that once lived in the Arctic.

For some time, no one knew what to make of that specimen or another mammoth fossil that was found on Melville Island to the northeast. Paleontologists knew that these big, hairy, elephant-like animals had lived in the Arctic at one time, but no one thought that their range extended beyond the north coast of the Yukon and Alaska on to the Arctic islands.

In time, paleontologist Richard Harington, the man who dated the fossil bone, came up with an explanation that seemed to satisfy most everyone then. Harington, arguably the world's most respected Ice Age paleontologist, suggested that Banks Island and parts of southwestern Melville Island were once part of the northeastern limit of Beringia, a verdant mass of lowland that periodically connected Arctic Russia to Arctic North America when sea levels were much lower than they are today because most of Earth's water was locked up in glaciers.

Over a period of tens of thousands of years, Harington suggested, most of those woolly mammoths that migrated across this continent sized lowland would have slowly moved southeast into Canada until massive sheets of ice that periodically expanded northwestward from the Hudson Bay region stopped them. He thought that some of them, however, may have stayed behind or retreated north across the ice sheets that connected the mainland to Banks Island when sea levels were so low.

Even today, many scientists assume that much of Banks Island and other parts of the western Arctic Archipelago were largely ice-free through the last period of glaciation and at least partially ice-free for hundreds of thousands of years before that. You can almost see it in the soft, verdant look of this treeless tundra on a warmish summer day. In places such as the Thomsen River valley, the sedge- and grass-covered terrain looks as if it had never been scoured by the sharp edges and heavy weight of ice that expanded to its Ice Age maximum 18,000 years ago before petering out 7,000 years later.

For most of his forty-year career conducting research in the Arctic, scientist John England also thought that Banks Island was a relatively undisturbed relic of an ancient world. Sometime in the 1990s, however, he and a handful of colleagues in the paleoenvironmental community saw something in the accumulation of geological evidence that suggested that this theory might be flawed.

England and I were standing on the tundra at Ballast Brook, the site of Hills's mammoth bone find, in the summer of 2012 when he described to me how he saw it all unfold. It was cold and bleak that day in August, just as it might have been when Hills had been there more than four decades earlier. England was waving his arms, much like a sketch artist might do in a courtroom, drawing a picture of a monstrous sheet of ice moving north from the mainland in super-slow motion, churning up granite and gravel, sand and stone, and possibly the bones of animals that may have died in its path (Figure 1.1). Banks Island may have been home to woolly mammoths and other Ice Age animals at one point in time, he told me, but if it had been, the animals were eventually displaced by this big sheet of ice.

"If there was such a population, it is surprising that no additional evidence has been found of any other animals like it," he said. "One bone on Melville, one on Banks? And the Melville sample was found below marine limit, the height of the postglacial sea level that inundated the land after ice retreat." He offered a different interpretation of the evidence: "That mammoth bone could have been rafted in by sea ice long after the animal from which it was derived, lived," he added. "How far away is anyone's guess."

England didn't arrive at this theory lightly.

The truth about how Banks Island and other parts of the Arctic have been shaped by climate, glaciers, and ice sheets has been germinating, evolving, and constantly changing as a result of the research that he, Harington, and many other scientists have been conducting in the circumpolar world. It all it points to a region that has undergone massive changes over the eons.

For the longest time, putting together the pieces of the puzzle to get a picture of the past proved to be elusive because radiocarbon dating is generally not reliable for dating anything more than 50,000 years old. Additionally, many important pieces of the puzzle were buried in permafrost, snowpack, and riverbeds in the most inaccessible parts of the world. Those that were found offered only a snapshot, not necessarily strong evidence of the land's complex evolution.

No one in Hills's day, however, expected this once very blurry picture of the past to unfold as clearly as it has. Two Smithsonian scientists, Charles Schuchert and David White,...