| 释义 |
▪ I. peneplain, n. Geomorphol.|ˈpiːnɪpleɪn|
Also -plane.
[f. pene- + plain n.1]
A low, nearly featureless tract of land of undulating relief, esp. one held to be the product of long-continued subaerial erosion of land undisturbed by crustal movement and to represent the penultimate stage in the cycle of erosion in a humid climate; also, a former surface of this kind as it exists today (e.g. after uplift and dissection, or buried as an unconformity).
1889W. M. Davis in Amer. Jrnl. Sci. XXXVII. 430 Given time enough, and the faulted ridges of Connecticut must be reduced to a low base-level plain. I believe that time enough has already been allowed, and that the strong Jurassic topography was really worn out somewhere in Cretaceous time, when all this part of the country was reduced to a nearly featureless plain, a ‘peneplain’, as I would call it, at a low level. 1893Bull. Dept. Geol. Univ. Calif. I. iv. 158 The tilting of the Sierra Nevada peneplane was also a post-Pliocene event. 1894Nation (N.Y.) 9 Aug. 99/2 A lowland of moderate relief close to sea level—a peneplain, as I should term it. 1933Geogr. Jrnl. LXXXI. 331 These ‘residual mountains’ rise from a peneplain, that is, a plain of erosion produced during a stable period interrupting an upward movement. 1934C. R. Longwell et al. Outl. Physical Geol. xv. 309 The highest ridges of the present Appalachians are remnants of a former peneplane. 1946L. D. Stamp Britain's Struct. xiii. 150 The magnificent modern sea-cliffs are where the peneplanes of the past meet the seas of to-day. 1954W. D. Thornbury Princ. Geomorphol. viii. 178 Although the peneplain still remains an important concept with most geomorphologists, it is now recognised that many topographic surfaces have been erroneously called peneplains. 1960B. W. Sparks Geomorphol. xv. 335 Good examples of peneplains are extremely rare and some would say that they do not exist. 1968J. Arnold Shell Bk. Country Crafts xxi. 255 The greater part of the many miles of walls [in Pembrokeshire] is composed of small boulders from the peneplain, which is mainly Cambrian. 1970R. J. Small Study of Landforms v. 164 Most peneplains in the British Isles take the form of ‘hill-top surfaces’, and are so fragmented that they are by no means easy to identify. 1977A. Hallam Planet Earth 301 He assumed a standard life-cycle for a river valley, marked by youth (steep-sided valleys), maturity (flood-plain floors), and old age as the river valley was worn lower and lower into a ‘peneplain’.
fig.1964Listener 27 Feb. 353/2 In the eyes of a stray bitch Ribbed with hunger, heavy with young, I saw the peneplain of all imagined Misery.
▪ II. peneplain, v. Geomorphol.|ˈpiːniːpleɪn|
Also -plane.
[f. prec. (after plane v.1), or a back-formation from next.]
trans. To erode to a peneplain.
1923[see kratogen]. 1931N. M. Fenneman Physiogr. Western U.S. iv. 172 The original folds of all these mountains were approximately peneplaned. 1969Bennison & Wright Geol. Hist. Brit. Isles viii. 181 The Old Red Sandstone of south-western Ireland rests on an irregular erosion surface which had not been peneplaned so that the beds are of variable thickness. 1970R. J. Small Study of Landforms v. 164 The English Chalk country..may well have been effectively peneplained during the Pliocene period. |