Hans Island, the tiny contested island between Greenland and Canada, is floating in more than just a sea of political controversy. For the past twenty years, the Nares Strait (the body of water surrounding Hans) has been the subject of scientific debate, challenging one of geology’s most universally-accepted theories: that of plate tectonics.
Alfred Wegener, the father of plate tectonics, believed that the world’s continents were once part of the same giant landmass, later breaking up and drifting into their present-day positions. Today, continents and ocean basins are thought to lie on rigid plates that are in continuous – albeit snail-paced – motion, and these movements, whether convergent or divergent, produce the world’s earthquakes and volcanic activity.
Plate tectonic theory is intuitively appealing – consider how the coastlines of Greenland, Baffin Island and Labrador fit together like jigsaw pieces. And for the most part, the geological evidence for continental drift is abundant. Scientists look for evidence of fault lines (fractures in continental rock) or spreading ridges (where the sea floor has split) and attempt to line up geological features on either side: comparable fossils, rock types, and evidence of glacial or other climatic activity. Using these clues, geologists can estimate how far plates have shifted on either side of a fault line, if at all.
But one of Wegener’s prime examples of continental drift – Greenland’s purported shift away from Canada 30 million years ago – is, for the most part, geologically unsubstantiated. Nobody has been able to find the fault that Wegener believed lay beneath the frozen, often unpassable waters of the Nares Strait.
Between 1998 and 2001, the Geological Survey of Canada sent a team of scientists to map the high arctic region near Hans Island, and to collect data about the area’s resource potential. The team sampled rocks on Greenland, Ellesmere and Hans Islands and conducted tests in the waters of the Nares Strait. A side-project – in collaboration with the German Federal Institute for Geosciences and Natural Resources –was to attempt to locate the Wegener Fault.
Chris Harrison, research scientist with the GSC, was a lead researcher
on the project and says the team simply couldn’t find the fault
under the Nares Strait.
“There is evidence of an ancient spreading ridge running down through Baffin Bay and Labrador Sea, but looking at the rocks up onshore on both Greenland and Ellesmere Island, we can’t see enough motion there. We need 300 km of motion on some fault and we simply can’t see it. There’s not enough indication in the rocks themselves that this fault exists.”
Even more problematic was the team’s discovery of an ancient dyke in the southernmost narrow of the Strait.
“We found that a geological bridge goes virtually all the way across from Inglefield Land on Greenland to near Cape Isabella on the Ellesmere side. And so you can’t run a major San Andreas-type fault through the southern part of the Nares Strait…It’s a very serious thorn in the side of the plate tectonic theory, at least in this part of the world.”
But Harrison still believes the ancient boundary between Greenland and Canada can be found.
“When you stand on Hans Island and you look to Greenland, what you see is a plateau. There are coastal cliffs that rise up150 meters and then behind that in some distance is the inland ice cap…. Whereas, when you turn and you look at Ellesmere Island, what you see is a substantial mountain belt.
And that’s quite important…Clearly the boundary between the mountains of Ellesmere and the plateau of Greenland - of which Hans Island is an eroded remnant – is a major boundary. A little bit like the big faulted boundary that separates the Rockies from the Plains.”
Harrison says there is new evidence that the Wegener fault may run onshore on northeastern Ellesmere Island.
“We can prove that there was about 75 km of displacement on that fault, and it’s in the correct direction – with Greenland moving north-eastwards and Ellesmere and the rest of North America moving south west…and we’ve found what may have been a part of Greenland on what is now Ellesmere Island, a part of North America.
But for the time being, Harrison says the Nares Strait region will continue to be a geological grey area, in addition to a political one.
“The problem is, the controversy surrounding the Wegener fault still exists,” he says.
“We’re still looking for the 225 km difference to make up that 300 km of motion.” |
