Natural Wonders: The Fossil Forest on Axel Heiberg Island

A 50-million-year-old forest of real wood lies on an uninhabited arctic island near the North Pole

At 80˚N and 2,500km from the nearest tree, you would not expect to find thick stumps, logs, and leaf litter from a primeval forest. But 50 million years ago, dawn redwoods, cypress, sycamore, and other temperate trees grew on now-barren Axel Heiberg Island in the Canadian High Arctic. Just a few kilometres away, fossils of turtles and alligators from the same Eocene era have also turned up. It’s as if this arctic island, now just 800km from the North Pole, once looked more like Louisiana.

 

How did this happen? While Axel Heiberg Island has drifted north on its continental plate over the millennia, it wasn’t that much further south, just around 70˚N. It still endured near-total darkness for much of the winter. But during that time, the Arctic was much warmer, with average July temperatures around 19˚C and average winter temperatures a little above freezing. In part, this is thanks to a thick blanket of clouds, which created a Venus-like heat trap.

The fossil forest is eroding out of a single, teardrop-shaped hill. Photo: Jerry Kobalenko

 

Axel Heiberg, first discovered in 1899 by Norwegian explorer Otto Sverdrup, is the world’s third-largest uninhabited island, and the tiny spot on which the fossil forest lies was not discovered until 1985. That summer, a helicopter pilot noticed a concentration of fossil logs and stumps from the air. He landed, had a quick look around, then reported his find to scientists. The next summer, one of them, James Basinger, returned to investigate.

Axel Heiberg’s fossil forest isn’t unique — there are half a dozen others on neighboring Ellesmere Island, for example — but it is by far the richest. Scientists have found over 200 trees, and more emerge all the time as erosion wears away the soft badland hillside. Some stumps are more than 2.5 metres in diameter and straight-sided logs suggest trees that grew up to 50m high.

A fossil stump

Photo: Jerry Kobalenko

 

What separates this fossil forest from other sites elsewhere in the world, such as Arizona’s Petrified Forest, is that these trees, branches, and logs, have not turned to stone. They have remained wood all this time. Basinger, the scientist who first studied the site, famously brewed a cup of tea on a small fire of 50-million-year-old twigs. Some of the cones and leaves are so well preserved that they look contemporary. You can smell the pitch on some of the newly emerged material.

This wood didn’t petrify because the original forest was abruptly buried in a flood and covered with at least a 200m-thick blanket of silt, which protected the trees and kept the silica in the water from replacing the carbon in the wood. Yet the trees were not buried so deeply that they turned to coal under the pressure. These floods were not common — they happened once every 10,000 years or so. Afterward, a new forest grew on top of the old one. There were 19 such floods on Axel Heiberg Island.

Very few people have ever visited the fossil forest on Axel Heiberg Island. Although it’s only 35km from a small weather station on nearby Ellesmere Island, it lies a little inland, and the only visitors — scientists, a few cruise ship passengers years ago, some military tourists from the weather station — have come by small plane or helicopter.