The dramatic landscape of the Nahanni karst, with its complex network of canyons and underground drainage systems, lies just outside the Nahanni National Park Reserve at the southern end of the Mackenzie Mountains.

Along with other earth scientists from UNBC, Agriculture & Agri-Food Canada, and McMaster University, I was part of a week-long expedition to this remote and fascinating area in mid-summer 2006. Supported by Parks Canada, our field studies collected new information on the evolution of this remarkable landscape.

The labyrinth karst occupies a low saddle between the Nahanni and Ram Plateaus, and consists of a 15-km-long belt of interlaced canyons, separated by expanses of almost bare limestone surfaces.

At ground level, this labyrinth of closed depressions and vertical-walled canyons is a challenge to explore on foot!

Most near-horizontal limestone surfaces have almost no soil cover. Where present, the soils consist of a thin veneer of silty material, likely of aeolian (wind-transported) origin.

The drainage system of the Nahanni karst is almost entirely underground. At the north end of the labyrinth, Raven Lake (left), and the large poljes (centre, right) have no surface outlets, and display large and rapid fluctuations in water levels, even from a single rainstorm.

(Photo: Scott Smith)

At higher elevations on the eastern flank of the Nahanni Plateau, the alpine landscape is dominated by extensive limestone pavements (left), intersected by major canyons (centre, right) with largely underground drainage systems.

Canal Canyon

Death Lake

Alpine soils on the Nahanni Plateau have formed in a thin, discontinuous veneer of silty materials, likely of aeolian origin. Scott Smith (Agriculture & Agri-Food Canada) and I dug a 5 m trench across a shallow depression in the limestone pavement surface, exposing the lateral variability in soil morphology.

The limestone pavement surface displays many of the dissolution features typical of karst landscapes.