Peneplain


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peneplain

[′pēn·ə‚plān]
(geology)

Peneplain

 

a denudation plain that has formed where mountainous regions were leveled under humid conditions. In contrast, there are plains whose initially flat relief was the result of accumulation.

The peneplain concept was introduced into geomorphology in the late 19th century by the American geographer W. M. Davis, who considered the peneplain a theoretically conceivable concluding stage of the geographic cycle. According to Davis, the mechanism of peneplain formation consists in the reduction of every point of the surface of a mountainous region by subaerial erosion, but Davis’ explanation is not universally recognized. L. King disagreed with such an explanation of planation and contrasted the concept of the pediplain to that of the peneplain.

Peneplains are formed at the end of major tectonic cycles during the transition from the orogenic stage of development of the earth’s crust to the platform stage. Thick weathering mantles form within peneplains. When tectonic subsidences occur, peneplains may become buried by sedimentary strata; when uplifts occur, peneplains become raised, as in the case of the syrts of the Tien-Shan.

A. E. KRIVOLUTSKII

References in periodicals archive ?
The final number of samples used was 140 (Marshes: 15; Dunes and Sands: 40; Croplands 12; Peneplains and Slopes: 36; Mountains 37).
The Sardinia Variscan peneplain is locally blanketed by scattered patches of post-Variscan successions that are Carboniferous, Permian and Triassic in age.
The elevated peneplain of Mount Rokko has maximum altitude of 932 m and its southeast border is limited by a series of NE-SW trend composed of Suma, Suwayama, and Gosukebashi fault (LIN et al., 1998; MARUYAMA; LIN, 2000).
The types of wood valued for making charcoal vary, but basically holm-oak and oak Quercus pyrenaica are used, which on the peneplain are often found forming dehesas--savannah-like grasslands with occasional stands of trees--(Santos et al.
Clearly those surfaces recorded at between 40-90 m asl, 118-132 m asl, and 173-187 m asl fall below the "Low Peneplain" of Brown (1960); the surface at between 219-229 m asl is also unlikely to correspond with the "Low Peneplain" because the altitudinal range ascribed to that surface is an order of magnitude greater than the surface recognized here.
These districts lie within the low-lying coastal peneplain. Drawdown failures occurred along river ways along which water advanced with the incoming wave and receded afterwards; this is visible clearly in the southern railway soil embankments.
Within the present metropolitan area, the oldest geological formation extends as a peneplain from Darebin Creek to east of the Dandenong Ranges and from north of Kangaroo Ground to near Lysterfield.
This area is part of a well-drained peneplain with lakes in the hollows and scattered depressions.
The origin of these surfaces is problematic: 1) Are they remnants of an ancient peneplain? 2) Are they the topographic expression of the roofs of sub-horizontal igneous sills?
Plagens characterizes the survey as a professional effort, "leaving the art alone to say what is, at least to me, uplifting in the short run, but then, as I worry about it all, a long, sloping, slight, but discernible peneplain of depression." And he hits the exhibition--and the implicit scene-making aspirations--where it hurts most: its inconsequentiality.
The area south and east of Taylorsville is a southeastward-sloping peneplain dissected by a close network of streams.
The area is a gently rolling peneplain above 200-m altitude with a few residual hills up to 350 m.