Your backyard geology

Throughout history, asbestos had been known as the miracle mineral due to its unique properties. The ancient Greeks wove wicks out of it for their oil lamps. They were known as the eternal lights because the wick did not burn down. Asbestos can be woven, it does not rot and it is waterproof. Marco Polo encountered cloth made from asbestos in China. It would not burn. In the late 1800s, the industrial age of asbestos began. Italy produced fireproof gloves, clothing and theatre curtains. With the invention of the automobile came new uses in brakes, clutches and gaskets. The early movie industry used it as fake snow on sets. Chrysotile or white asbestos is the most common type, comprising more than 90 per cent of all that was mined. The other common types are amosite, or brown asbestos, and crocidolite, known as blue asbestos.

The formation of asbestos starts on the seafloor where two tectonic plates are spreading apart and magma is upwelling from deep in the earth. This forms oceanic crust in the form of rocks known as ultramafics. The newly formed rocks contain magnesium, iron, silicon and oxygen. Over time the rocks absorb seawater into their chemical structure, forming a rock known as serpentinite, named for its serpent-like texture, which is green, slippery and similar to fish scales.

Over millions of years, serpentinite is subjected to tectonic forces that push it to the surface. This fractures the rock and groundwater is warmed from the friction of the sliding rocks. Warm water starts circulating through the fractures absorbing the minerals from the serpentinite. When the water cools, asbestos crystals grow and fill the fractures.

At Clinton Creek, 75 kilometres northwest of Dawson City, an asbestos mine operated from 1967 to 1978. That mine and its older sister, British Columbia’s Cassiar mine, southwest of Watson Lake, were both operated by the Cassiar Asbestos Corporation. The larger Cassiar mine operated from 1953 to 1993.

In 1887, placer miners in the Forty Mile area knew of asbestos fibres in Clinton Creek. The discovery of the Clinton Creek deposit is one of determination and cooperation by some knowledgeable and curious Yukoners. The story is told in detail in an orientation booklet called “Clinton Creek,” given to new workers at the Clinton Creek mine in the 1970s.

It starts on Cassiar Creek, 20 kilometres up the Yukon River from Forty Mile. Willie and Walter DeWolfe (sons of the “Ironman of the North,” Percy DeWolfe) found asbestos on their trapline there. In 1955 they brought some samples to Fred Caley, a merchant and prospector who lived in Dawson and had a general store on Third Avenue. He knew what asbestos was and had many mining contacts. Caley grubstaked the DeWolfes and others to stake some claims. These claims were optioned to Conwest Exploration, an arm of Cassiar Asbestos Corporation, but it turned out the “Caley” deposit was too small for a standalone mine.

In February 1957, Arthur Anderson was talking to Fred Caley. Anderson had a trapline on Clinton Creek. In the 1940s, Anderson and his dad came across some asbestos-bearing rocks. They collected some samples and kept them in their cabin. When Caley showed Anderson some samples he had from Cassiar Creek, Anderson told Fred he found similar rocks on Clinton Creek many years before. Caley grubstaked Anderson and another trapper, George Walters, to find the spot and stake some claims. It was April and there was lots of snow on the ground, so it was not easy to find the spot, but they persevered, found the asbestos showing and staked claims. By June, Cassiar Asbestos had optioned the property. Soon after, Dawson contractor Dick Gillespie bulldozed a 60-kilometre road into the property from what is now the Top of the World Highway. The company brought in equipment and started trenching, drilling and underground sampling in 1957.


It was not until 1964 that a decision was made to go into production. Things started to happen. An airstrip (still one of the longest in the Yukon) was put in by the mine site. A crusher, mill and tramline needed to be constructed. To house the expected 300 employees, a town had to be built.

First, a bridge was built over the Fortymile River. Until then, people had been using a barge to get across the river. In the middle of the winter of 1965/66, in temperatures of -50 C, concrete was poured and a bridge erected. A town site for 500 people was selected at the confluence of Clinton Creek and the Fortymile River, nine kilometres from the mine. The site had permafrost, so all the buildings were built on cedar piles that were embedded five metres into the icy soil.

The town was ahead of its time. It reused waste heat from the diesel electric generators to warm water. There was a central heating plant for all the large buildings in town. It also had the first sewage treatment plant in the territory. Clinton Creek was the westernmost community in the country, only 13 kilometres from the Alaska border. There was the Malamute Saloon, curling rink, recreation centre, medical clinic and a monthly newspaper called The Rock Fluff.

Fluff refers to the process used in the mill to extract the asbestos from the rock. When the rock is crushed and screened, the asbestos is freed and fluffs up, floating on top of the rock. From there it is vacuumed up. It is sorted and graded by size and blown into 45 kilogram bags. Clinton Creek asbestos was known for its good quality and long fibres. It was shipped around the world and rumoured to have been used on the space shuttle. Prime Minister Trudeau visited the mine in 1968.

It was in the early 1900s that health hazards related to asbestos fibres were recognized. Mill workers were getting lung diseases and dying. Inhalation of asbestos is now known to cause asbestosis, scarring of lung tissue and mesothelioma, cancer of the lining of the lungs.

It was 1979 when the manufacture of asbestos products was banned in Canada. It could still be mined and exported. Legislation halting the export and import of asbestos in Canada did not pass until 2018. A few exemptions remain for nuclear facilities and the military. You can find a bit of asbestos in a number of serpentinite rock outcrops in the Yukon, including the Midnight Dome in Dawson City, the southeast end of Marsh Lake, and Monarch Mountain near Atlin. Asbestos has been shown to absorb carbon dioxide from the atmosphere. Dr. Greg Dipple of the University of British Columbia has tested the Clinton Creek tailings and has shown that the carbon dioxide reacts with the serpentinite rock and becomes fixed in the chemical structure. Tailings work best because of the greater surface area of the mineral exposed. In theory, such a mine today would be naturally carbon neutral throughout its operation.

The road to Clinton Creek starts about 60 kilometres from Dawson on the Top of the World highway. The mine site itself is now the responsibility of the Government of Yukon as an abandoned site. Access is prohibited. The former town site of Clinton Creek is now privately owned. Many of the original houses were moved intact to Dawson after the mine closed down.

The drive down the Clinton Creek road is worthwhile. About 53 kilometres down, just before the Fortymile River bridge, take the road to the right. It will lead you to the Yukon River where you can walk in the 1.5-kilometre trail to the Forty Mile town site. It is now a historical site co-managed by the Tr’ondëk Hwëch’in First Nation and the Government of Yukon. Talented local tradespeople are stabilizing and restoring the buildings at this beautiful location.

Telegraph Creek area