Southwards from here, the Dempster Highway lies along the edge of a 200 million year-old sea. Evidence of that ancient sea is preserved as limestone and other sedimentary rocks up to 10 km thick that form much of the Richardson Mountains. Corals that once lived in this sea can be found as fossils scattered in the limestone beds along the highway. Water continues to be a powerful force in this sub-arctic region. The underlying permanently frozen ground (permafrost) causes patterns, like polygons and circles, on level ground and pushes rocks to the surface, creating rock streams, on slopes. Surface thawing can cause soil to flow down steep slopes to create long looping ridges, or solifluction terraces.
Much of the landscape below the steep mountain slopes is tussock tundra vegetation. The most common plant here is Cottongrass (Eriophorum vaginatum), although there are a variety of others all adapted to a very wet and cold environment. Soils are frozen most of the year and even in summer thaw only to a depth of 25 to 40 cm. The rock, soil and ice below 40 cm never rises in temperature above 0 Celsius. Permafrost acts as an impermeable barrier that prevents water from draining out of the root zone.
The remote and empty appearance of the landscape in this part of the Yukon is deceptive. As you travel along the Richardson Mountain foothills, you will pass through a region which preserves an exceptionally large number of prehistoric sites. Archaeologists have found hundreds of broken and discarded stone spears, knives, and hide and meat processing tools. These abundant remains of ancient camps relate to a many-thousand-year tradition of hunting the Porcupine Caribou Herd on its annual migration along the mountain front. Because this region is part of Beringia, human occupations date to the end of the Ice Age, more than 10,000 years ago.
In more recent times, these territories were hunted by both the Tukudh and Teetl'it Gwich'in, whose descendants now reside in Old Crow and Fort McPherson. The Dempster Highway follows one of several routes used traditionally by these communities through the Richardson Mountains. In times past, the "Peel River people" regularly hunted with Tukudh Gwich'in relatives when the appearance of thousands of migrating caribou drew everyone into the foothills on the Yukon side.
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