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Sahtu sinkholes continue to fascinate
Cluster of seven caverns dot landscape 50 km outside Norman Wells

Elaine Anselmi
Northern News Services
Monday, February 23, 2015

Within 50 km northwest of Norman Wells, sinkholes in varying stages of formation are collapsing into the earth.

NNSL photo/graphic

A major sinkhole near Bear Rock, outside of Tulita, was photographed by Eric Mcleod in 2013. - photo courtesy of Eric Mcleod

"Six are in the same area and then there's one big one, a seventh, about 50 metres away," said Eric Mcleod, who does engine maintenance on helicopter-accessible sites throughout the North. "Some have started and they've got trees in them, others have just started to drop but the trees are sloping in, some have 30 to 40 feet of exposed rock."

Mcleod first noticed the collection of sinkholes while on a commercial flight out of Norman Wells 13 years ago. Spending a significant amount of time in helicopters for work, he was able to get a closer look.

"There are a couple of sinkholes I've found, one that's fairly well-known between Tulita and Norman Wells, northwest of Bear Rock," Mcleod said. Bear Rock is a rock formation just northwest of Tulita which has significance tied to the Dene hero Yamoria.

This group of sinkholes, Mcleod said, is between Norman Wells and Fort Good Hope and far off the winter road.

While the largest sink hole he's seen is the one near Tulita, Mcleod said several of the holes in the cluster are large enough to fit a helicopter.

A report on karst landscapes, or landscapes prone to sinkholes, in the Norman Wells region was completed for the Department of Environment and Natural Resources in 2008.

Author Derek Ford, a professor emeritus in Geography and Earth Sciences at McMaster University, pointed out several sinkholes, saying they range "from a few metres to hundreds of metres in diameter and up to 100 metres or more in depth."

In the Sahtu, these formations are generally have two causes. Either they are formed by runoff of surface water sending the flow into an underground cave system or through the collapse of a cave underground, according to the report. Soluble rocks, such as limestone and dolomite, erode to create these caves. In Norman Wells, Ford noted there is an abundance of karst features in the dolomite.

"This is the stuff that makes the North what it is," Mcleod said. "I can post all of these pictures on Facebook, but it seems that in my mind, it's not doing the North justice in regards to some of the things I get to see on a regular basis."

Based out of Inuvik, Mcleod's work takes him from north of Fort Good Hope to south of Fort Simpson, as well as on-road sites along the Dempster Highway. He is trained to work out of helicopters on remote sites such as Eagle Plains, Yukon, three sites north of Tuktoyaktuk and the diamond mines for Atco Structures.

"There isn't a lot I haven't seen going up and down the Mackenzie River," he said.

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