Nahanni National Park Reserve in the Dehcho Region of the Northwest Territories, Canada, approximately 500 km west of Yellowknife, protects a portion of the Mackenzie Mountains Natural Region. The centrepiece of the park is the South Nahanni River. Four noteworthy canyons reaching 1,000 m in depth, called First, Second, Third and Fourth Canyon, line this spectacular whitewater river.
The Rabbitkettle Tufa Mounds are the largest of tufa mounds in Canada. The largest of the mounds is 27m high and 74m across. The source of the springs comes from deep in the earths crust, near the base of the granite batholiths that form the Ragged Range. The volcanic activity that raised the mountains still heats the water deep below the surface of the earth. The heated water percolates upwards, dissolving calcium carbonate from limestone deposits on its way by. When it reaches the surface springs, the water cools and the calcium carbonate particles are released. These microscopic particles settle to form porous calcite rims around the pools of water. These pools range in size from bathtub to fingernail size. This process takes a great deal of time, and it is believed that the mounds themselves are around 10, 000 years old, their creation beginning at the end of the last ice age. These rare and fragile features are protected as a Zone 1, Special Preservation Area, and all visitors must be accompanied by Parks Canada Staff in order to minimize impact.