When the world was young: Fossil-hunting on Axel Heiberg
Patient Canadian researchers try to understand what the world was like in ancient times by decipering the clues found in fossils.
AXEL HEIBERG ISLAND, Nunavut — On this remote High Arctic island, by the edge of a fast-running river, millions of years are tumbling down into the water.
With little vegetation to hold the soil together, earth and rocks constantly break off along the river’s edge, creating fantastic clouds of dust as they fall.
And each time this happens, the fossils of trees and plants that grew here more than 40 million years ago are lost, carried away to the ocean or slowly dissolved in the swift current. The fragments of mummified wood are batted around in the water or cast up on the shore. Boulders embossed with the imprints of leaves are piled along the bank.
“It’s like a fossil superstore,” said Yusheng Liu, a fossil plant biologist, originally from China.
Liu expertly hammers a thick, nondescript grey rock into sheets and quickly uncovers several remnants of leaves, some in almost mint condition, that were hidden in the clay.
Liu, a researcher, is a member of a team of four from the University of Saskatchewan, all students of paleo-botany — the study of ancient plant life.
“Canada has so many fossils, but so few paleontologists,” marveled Liu. “We have so much to learn.”
While the quantity of fossils on Axel Heiberg is unusual, so is their quality, because they’re not petrified, or turned to stone, but rather mummified or simply pressed into clay.
Fossil bones are much rarer because the soil’s acidity appears to have dissolved the bones’ calcium. Only a few teeth from a moose-like creature called the “Titano” and some beetle cases have been uncovered in the Geodetic Hills, although on the basis of the large number of nuts and seeds found, most paleontologists believe squirrel-like animals existed, too.
While fossil gathering, the team mainly concentrates on the rocks by the water and on the exposed leaf litter that sticks out of the eroding outcrop above. They try not to disturb any materials that aren’t already at risk from erosion. Their only tools are a small pick-axe, a jackknife and a magnifying glass.
Some clay boulders contain a treasure trove of fossils. The group examines each chunk for fossils, and they’re elated to find several intact leaves.
“Leaves are rare — so that’s why we get so excited,” said graduate student Donna Postnikoff.
Liu is especially pleased when he finds a well-preserved seed, cone or leaf. Most of the fossil leaves come from the huge Dawn Redwood or meta-sequoia which flourished here during the warmer Eocene Era, some 45 million years ago.
This tall tree shed its leaves every year, casting thousands of its distinctive fronds on the ground, many of which survived the passage of time.
Liu also finds leaves from beech trees, kiwi-like seeds, and cones from evergreens.
Studying such fossils under an electron microscope can reveal the levels of oxygen and carbon dioxide that existed in the atmosphere of that much warmer period, and how these plants differ from their modern counterparts.
“The plants here are very good, so that you can look at them under the microscope,” said Liu. “If we study these fossils, we can get an image of the paleo-vegetation and we can use it to reconstruct the climate, because it’s a good indicator of the climate.”
Every fossil selected for further study is sprayed with latex to keep the plant tissues fresh. Then, it’s wrapped up in newspaper and taped, so that it will travel without breaking. Months later, the scientists will carefully unwrap the fossils.
“We’re very selective,” said Postnikoff. “But if we put it in the drawer for later, at least we will be able to study it.”
After an afternoon by the river, the team heads back to camp, weighed down by heavy, clay rocks.
Their field camp is a small group of tents pitched on a rocky slope. In mid-July, they’re one of 26 similarly isolated camps spread around the High Arctic that the Polar Continental Shelf Project keeps tabs on, by calling in twice a day by radio, at 7 am and 7 pm.
After a couple of days by the river, this group will move on to another site, by the Fossil Forest. There, they continue their visual search for exposed fossil plants.
In all, the researchers spend just a little more than two weeks on Axel Heiberg, but they’ll spend many more months studying the fossils and adding more information to the pool of knowledge that already exists about these ancient plants.
“But I don’t have to do it all this year and get all the answers,” said Postnikoff who has spent part of the past four summers fossil-hunting in the High Arctic. “My children can also do it.”