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. Peneplains are sometimes associated with the cycle of erosion theory of William Morris Davis.[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. By some definitions peneplains grade down to a base level represented by sea level, yet in other definitions such a condition is ignored. A common misconception about peneplains is that they ought to be featureless.
- 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.
- 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.
- 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.
- Migoń, Piotr (2004). "Peneplain". In Goudie, A.S. Encyclopedia of Geomorphology. pp. 771–772.