The South Nahanni: High-Latitude Limestone Landscapes

  • Derek Ford


South Nahanni River drains a basin of ∼34,000 km2 at 61°N in the remote Mackenzie Mountains of the Northwest Territories, Canada. In its central sector it flows through a never-glaciated zone where resistant limestones, dolomites, and sandstones are folded into regular anticline and overthrust topography rising to 2,000 m a.s.l. Permafrost is widespread below 1,200 m, technically continuous above. The river has carved three magnificent antecedent meandering canyons through the anticlines. The Nahanni Formation (Devonian) is an ideal platformal karstic limestone 180 m thick, resting on 800 m of karstifiable dolomites in the First Canyon. Relict caves in the canyon contain ancient phases of speleothem growth that were investigated in some of the pioneer applications of U series dating to geomorphic questions, such as rates of canyon entrenchment. The most accentuated surface karst landforms known in any arctic or sub-arctic region extend as a belt for 40 km north of First Canyon. A natural labyrinth of solutional corridors, plus sinkholes and small poljes has developed in the limestone there, modified by scabland glacial outbursts when water was impounded by Laurentide Glacier ice from the east. Modern drainage is all underground, over distances up to 25 km and rates >3,500 m/day in both limestones and dolomites. Northwest of the main belt an ancient upland karst has been gutted by canyon recession and periglacial action. In contrast, most of a younger anticline to the northeast was not stripped of shale cover strata until the regional permafrost was well established: there are deeply entrenched canyons but little karst in either limestone or dolomite as a consequence.


Antecedent river canyons aquifers caves karst neotectonics permafrost periglacial processes 



Field research in the magnificent but remote Nahanni country has relied upon the vigorous support of geomorphology students and cave enthusiasts for many years. Particular thanks to Steve Catto, Marcel Cholo, and Dana Haggarty of Parks Canada for their company and logistic support in 2006 and 2007. Paul Sanborn, Jacques Schroeder, and Steve Worthington have freely made their photographs available. The Natural Sciences and Engineering Research Council of Canada and Parks Canada are thanked for financial aid.


  1. Brook GA (1976) Karst terrains of the South Nahanni area, Mackenzie Mountains. N.W.T. Ph.D. thesis, McMaster UniversityGoogle Scholar
  2. Brook GA, Ford DC (1978) The nature of labyrinth karst and its implications for climaspecific models of tower karst. Nature 275:493–496CrossRefGoogle Scholar
  3. Brook GA, Ford DC (1980) Hydrology of the Nahanni Karst, northern Canada, and the importance of extreme summer storms. J Hydrol 46:103–121CrossRefGoogle Scholar
  4. Ford DC (1973) Development of the canyons of the South Nahanni River, N.W.T. Can J Earth Sci 10:366–378Google Scholar
  5. Ford DC (1974) Evidences of multiple glaciation in South Nahanni National Park, Mackenzie Mountains, N.W.T. Can J Earth Sci 13:1433–1445Google Scholar
  6. Ford DC (1991) Antecedent canyons of the South Nahanni River. Can Geogr 35:426–431CrossRefGoogle Scholar
  7. Ford DC, Williams PW (2007) Karst Hydrogeology and Geomorphology. Wiley, ChichesterGoogle Scholar
  8. Harmon RS, Ford DC, Schwarcz HP (1977) Interglacial chronology of the Rocky and Mackenzie Mountains based upon 230/Th234 U dating of calcite speleothems. Can J Earth Sci 14:2543–2552CrossRefGoogle Scholar
  9. Schroeder J (1977) Les formes de glaces des grottes de la Nahanni, T.N.O. Can J Earth Sci 14:1179–1185Google Scholar
  10. Schroeder J (1979). Le développement des grottes dans la région du Premier Canyon de la rivière Nahanni Sud. T.N.-O. Ph.D. thesis, University of OttawaGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • Derek Ford
    • 1
  1. 1.McMaster UniversityOntarioCanada

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