Forty Mile: Landscape
Summer view of the Cloudy Range at the confluence of the Yukon and Fortymile rivers.
Winter view of the Cloudy Range at the confluence of the Yukon and Fortymile rivers.
Forty Mile lies in a broad valley at the confluence of the Yukon and Fortymile rivers. The valley is flanked by low, rounded mountains. The site is part of Beringia, a great band of land extending from Siberia to the Northwest Territories that remained unglaciated during the last major ice age between about 10 and 25,000 years ago. This area is rich in minerals which include gold, asbestos and coal deposits.
Forty Mile also lies within the Tintina Trench, an immense valley that traverses the Yukon Territory from southeast to northwest. The eight-million-year-old Trench is underlain by a huge fault along which bedrock has shifted as much as 450 km. It is an important wildlife migration route and a flyway for species such as sandhill cranes, swans and peregrine falcons.
The presence of permafrost in the ground has done much to shape and alter the landscape. When covered with insulating vegetation, this permanently frozen ground can be quite stable. Unfortunately, early builders did not understand this and cleared the ground to erect their buildings. The frozen ground, stripped of its cover, then melted and froze again causing the surface to sink and heave. The buildings sitting on this active ground also shifted and buckled, causing rapid deterioration.