Peneplain

Aerial view of the almost flat and drowned peneplain at Belcher Islands, Hudson Bay, Canada. Note that the peneplain cuts across numerous folds.

In geomorphology and geology a peneplain is a low-relief non-constructional plain. This is the definition in the broadest of terms, albeit with frequency the usage of peneplain is meant to imply the representation of a near-final (or penultimate) stage of fluvial erosion during times of extended tectonic stability.[1] Peneplains are sometimes associated with the cycle of erosion theory of William Morris Davis.[1][note 1]

The existence of some peneplains, and peneplanation as a geomorphological process, is not without controversy, due to a lack of contemporary examples and uncertainty in identifying relic examples.[1][3] By some definitions peneplains grade down to a base level represented by sea level, yet in other definitions such a condition is ignored.[3] A common misconception about peneplains is that they ought to be featureless.[3]

Canisteo River Valley from Pinnacle State Park, New York. The distant peaks at the same elevation represent the remnants of a peneplain that was uplifted to form the Allegheny Plateau, which is a dissected plateau in southwestern New York. In this area, the sharp relief that is seen on some of the Allegheny Plateau has been rounded by glaciation.

See also

Notes

  1. ↑ The term was coined around 1900 by William Morris Davis who described it as follows: Given sufficient time for the action of denuding forces on a mass of land standing fixed with reference to a constant base-level, and it must be worn down so low and so smooth, that it would fully deserve the name of a plain. But it is very unusual for a mass of land to maintain a fixed position as long as is here assumed.... I have therefore elsewhere suggested that an old region, nearly base-levelled, should be called an almost-plain; that is a peneplain.[1][2]

References

  1. 1 2 3 4 Phillips, Jonathan D. (2002), "Erosion, isostatic response, and the missing peneplains", Geomorphology, Vol. 45, No. 3-4. Elsevier, 15 June 2002, pp. 225-241. doi:10.1016/S0169-555X(01)00156-8.
  2. ↑ Chorley, R.J. (1973). The History and Study of Landforms or The Development of Geomorphology. Vol. Two: The Life and Work of William Morris Davis, Methuen.
  3. 1 2 3 Migoń, Piotr (2004). "Peneplain". In Goudie, A.S. Encyclopedia of Geomorphology. pp. 771–772.
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