Arctic Dreams Birding Tour > Wilderness Area
Tombstone Territorial Park
The Tombstone Mountains are in fact a distinct range within the Southern Ogilvie Mountains. They are famous for their stunning topography, jagged ridges and immense vertical faces of imposing rock, some more than 2000 feet high: hence the name “Tombstones”. Its geological history is quite interesting. The Tombstones were not thrust up from the earth due to plate tectonics, as many mountains are, but rather the story of the Tombstones is a darker affair, having its beginning deep in the earth’s crust. Here hot molten-lava surged into cracks in the earth’s crust and then slowly cooled, creating a fine-grained and quite hard rock known as syenite. As time passed the softer sedimentary rock in which the Tombstones cooled, the “overburden” as it’s called, eroded away to slowly reveal the Tombstones, which due to their hardness were better able to resist erosion.
The Tombstone Mountains are situated
right at the edge of Beringia, a zone of Alaska and the Yukon that
remained ice-free during the periods of glaciation. This ice-free
zone was caused by the rain-shadow effect of the tall Costal Mountains
of the pacific-northwest. The Tombstones, however, did not escape
the ice. The immense sheets of ice scoured the land creating
u-shaped valley bottoms and such distinct features as arêtes: thin
razor-like ridges formed by the erosive force of parallel valley
glaciers.
Dempster Highway
Modern-day access to the park was made possible by the construction of the Dempster Highway, which was begun in 1959 but not fully completed until 1979. The highway is named after Inspector William Dempster of the Royal Northwest Mounted Police, who headed the search for the infamous Lost Patrol. The Dempster Highway is Canada’s northernmost highway, stretching 671 km (417 miles) to the town of Inuvik, Northwest Territories. It is an engineering triumph. Designers had to pioneer new techniques for building on permafrost, such as laying down a gravel pad 1.5- -2.5m (4-8 feet ) in thickness to insulate the permafrost below from the heat of the short, but sometimes intense, summer. Without this thick layer of insulating gravel the highway would literally sink into the ground. The highway is famous for its stunning fall colours, unsurpassed wilderness, and amazing opportunities to view wildlife.
The Richardson Mountains
The Richardson Mountains are situated in the far north of the Yukon.
The northern half of the Richardson’s straddles the Yukon/Northwest
Territories border, running in a north to south orientation. These
barren and wind-swept mountains are considered by cartographers to be a
sub-system of the Brooks Range, which is primarily in Alaska. Another
range known as the British Mountains in the extreme northwest of the
Yukon runs in a west to southeast orientation and joins the two
systems. When combined with the British Mountains and Brooks Range the
Richardson Mountains are the eastern edge of a crescent-shaped
mountain range that spans almost 1400 km (870 miles) to the western
coast of Alaska.
The western edge of the Richardson’s are part of an area known as Beringia, which remained glacier-free during the ice-age. The glaciers did not form due to the dry climate created by the rain-shadow effect of the large Coastal Mountains of the Pacific Northwest. Many relic plants inhabit these slopes that are not found elsewhere in the Yukon. The gentle rounded slopes do not show the classic u-shaped valley bottoms of glaciated mountains to the south, which were created by the scouring and gouging power of 3 km thick sheets of ice. Rather they are softened at the edges by a few million years of freezing and thawing and high winds, let still show distinct folds and form v-shaped valleys, typical of non-glaciated mountains.
