Avalanche safety zone, Atigun Pass, Alaska
Source: Museum Victoria
Museum Victoria’s Tom Rich, Senior Curator, Vertebrate Palaentology, discusses digging for dinosaurs in Alaska:
Why would an Australian palaeontologist be interested in the polar dinosaurs of Alaska? Because 100 million years ago, southeastern Australia was well inside the southern polar region of the day.
Eighteen years ago while visiting a joint palaeontological field party collecting dinosaurs from permafrost exposed on the left bank of Alaska's Colville River, a bank slump occurred under the summer sun.
As ten tonnes of mud missed me by about five metres and slid into the river, I couldn’t help but wonder why we were working out in the open like sitting ducks. Particularly since the site's discoverer, Liscomb, had died in a landslide a few years after locating it.
It occurred to me that it might be safer to cut a tunnel into the permafrost using techniques long known to Alaskan miners. With a snow shed at the entrance so any slumps would not cover it, work could proceed more safely. Recovered bones would also not go through the freeze-thaw process and thus be in better shape than those collected close to the surface.
After 18 years of trying to find funding to trial this approach, last April an adit (horizontal tunnel) was cut into the permafrost on the Colville River’s left bank at 70 degrees 5' N, 151 degrees 33' W.
Cut into the rocks immediately above, rather than into the fossil layer itself, it gives airspace to work so that fossils buried in the adit's floor can be extracted by working down onto them instead of horizontally. It also makes it easier to collect fossils intact.
The Colville River dinosaurs are particularly important because the rocks on the left bank, which extends more than 200 km, are the richest known polar dinosaur site on Earth. They also are the only known location with potential for collecting dinosaurs spanning 40 million years—elsewhere that polar dinosaurs are known, they represent a single moment of geologic time.
Phase two of the dig is occurring right now, during a month-long return to excavate the floor. The objective is not only to collect fossils, but to refine the techniques for doing so. Then if others wish to apply the same procedure at other sites along the left bank in future, they will gain maximum benefit from our experience.