Following the Silver Trail

Natural History, July, 2001 by Robert H. Mohlenbrock

Vestiges of mining towns line a route into the central Yukon.

Canada's northwesternmost territory, the Yukon, has just two major highways--the Alaska Highway, which runs east to west across the southern part of the region, and the Klondike Highway, which starts south of Whitehorse (the territory's capital) and runs northwest through Stewart Crossing to Dawson City. The great Klondike gold rush, which followed the discovery of gold along Bonanza Creek in 1896, was responsible for making Dawson City a major town. Stewart Crossing is near Stewart Creek and Duncan Creek, where gold was discovered in 1895 and 1889, respectively. Silver-rich deposits of galena, a lead ore, were mined in an area northeast of Stewart Crossing. The road leading there, which strings together the three towns of Mayo, Elsa, and Keno City, is still known as the Silver Trail.

One cool August morning, my wife, Beverly, and I got an early start out of Whitehorse and followed the Klondike Highway for 120 miles, to the few buildings that remain of Stewart Crossing. We then turned onto the Silver Trail, which at first follows the Stewart River upstream. After about two miles, our view of the river was obscured by a white spruce forest. The forest grows atop permafrost, a layer of soil that remains frozen year-round. A dense ground cover of mosses provides insulation during the summer, helping to preserve the permafrost below.

Another ten miles or so down the road, the landscape broadened into a floodplain, and twenty miles farther along, we saw a pair of low ridges. These are moraines--glacial deposits of sand and boulders--marking the western limit of glacial ice in the Stewart River Valley some 14,000 years ago, during the most recent ice age. East of here, geologist Christopher Burn has reported, the area was once covered by ice up to 1,500 feet thick.

Just outside Mayo, thirty-six miles along the Silver Trail--about the halfway point--we reached a bed-and-breakfast where we had arranged to spend two nights. Mayo, which once boasted 30,000 inhabitants, now has about 500. Nevertheless, it is the region's center of activity. (Elsa is nearly a ghost town, with less than half a dozen residents, while Keno City has about twenty-five.) Coincidentally, Mayo holds the record for both the coldest and the hottest temperatures in the Yukon. In February 1949, a low of --80 [degrees] F was recorded, while in June 1967, the temperature rose to 97 [degrees] F.

After we had spent the night, the host of our bed-and-breakfast drove us to Keno City. On the way, near the former settlement of Minto Bridge, we stopped to see a "drunken" forest of spruce trees tilted at various angles. The forest owes its appearance to an adjacent lake, one of a number of thermokarst lakes in the region. Such lakes originate from the melting of ice in the upper layer of permafrost; in this case, according to Burn, the melting resulted from nineteenth-century forest fires. Because the lake does not freeze to the bottom in winter, deeper layers of permafrost beneath it, as well as the frozen soil around it, continue to thaw. As the banks of the lake collapse, the trees begin to topple.

The trip to Keno City gave me the opportunity to see Keno Hill, which rises several hundred feet above the town. Reaching 6,755 feet above sea level, the top of the hill is above the timberline, and several plants unusual for this part of Canada grow here. A rough road leads up to the summit, passing first through one of the northernmost stands of alpine fir in the world. On the way up, we stopped to examine the roadside vegetation in this forest and again, above the timberline, to see a wet meadow and a dry meadow. Finally we reached the rocky summit, which harbors tiny flowering plants. In most of these species, the leaves are crowded into a compact "cushion" that protects them from the harsh, drying winds.

Robert H. Mohlenbrock, professor emeritus of plant biology at Southern Illinois University, Carbondale, explores the biological and geological highlights of U. S. national forests and other parklands.

For visitor information, contact: Yukon Department of Tourism P. O. Box 2703 Whitehorse, Yukon, Canada Y1A 2C6 (867) 667-5036 www.touryukon.com