Peneplain

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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 who also coined the term around 1900.[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][2] By some definitions peneplains grade down to a base level represented by sea level, yet in other definitions such a condition is ignored.[2] A common misconception about peneplains is that they ought to be featureless.[2]

Usage by W.M. Davis[edit]

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.

The term was coined 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.

—W.M. Davis[3]

See also[edit]

References[edit]

  1. ^ a b c 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. ^ a b c Migoń, Piotr (2004). "Peneplain". In Goudie, A.S. Encyclopedia of Geomorphology. pp. 771–772. 
  3. ^ 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.