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The Parks / Northwest Territories / Nahanni National Park Reserve

The process of water dissolving limestone results in landforms known as karst formations. Sinkholes, caves and underground waterways are all a part of a karst topography evident in the 120 cave openings on the north face of First Canyon, and in the canyons and lakes of the Ram Plateau beyond. Water seeps into the porous rock creating underground passages to the water table below. As the land rose, the water sought lower and lower levels, leaving caves and channels in the rock above it. In many places, a sinkhole results from the land collapsing into an underground space, later filling with rain and meltwater to form a lake which appears to have no outlet. But the outlet is simply hidden, draining into the complex system of waterways that run underground to the Nahanni River. Raven Lake is a magnificent example of this type of karst formation, a perfect circle of water sunk deep into the limestone plateau.

The Grotte Valerie is the best known of the Nahanni cave systems. Its subterranean passages vary in size from grand chambers and tunnels to impassable cracks in the rock walls. At one time, park visitors who explored these caves discovered delicate ice sculptures and a frozen waterfall that ended in a large chamber now christened ‘Gallery of the Dead Sheep’. Sometime during the last 2000 years, over 100 Dall sheep had explored these caves only to find themselves trapped at the bottom edge of a steep wall of ice with no food and no exit. Their skeletons are an eerie reminder of the dangers of cave exploration. Grotte Valerie is a Class 1 sensitive area and consequently off limits to park visitors today.