| 释义 |
knickpoint Geomorphol.|ˈnɪkpɔɪnt|
Also nickpoint and as two words.
[Partial tr. G. knickpunkt, f. knick (see knick n.2) + punkt point.]
A break of slope in a river profile, esp. one where a new curve of erosion arising from rejuvenation intersects an earlier curve.
1924Bull. Geol. Soc. Amer. XXXV. 638 Since erosion progresses headward when a region is uplifted by a uniform tilting movement.., the longitudinal profiles of those streams will record a knickpoint at the headward limit of quickened erosion. 1937Wooldridge & Morgan Physical Basis Geogr. xv. 220 The rate of upstream recession of knickpoints will evidently vary with the character of rocks eroded. 1954W. D. Thornbury Princ. Geomorphol. v. 110 Along some streams..nickpoints are found which do not seem to be related to more resistant rock. 1967J. Challinor Dict. Geol. (ed. 3) 142/2 To the present writer it seems that nearly all knick points are due to some commoner and more compelling cause [than rejuvenation], such as the outcropping of a hard bed or glacial erosion. 1968C. R. Twidale Geomorphol. vi. 190 Not all falls and rapids indicate nick points, for hard-rock strata crossing the river's path may well produce a break of slope. 1973Nature 9 Nov. 75/1 Recession of valley nickpoints inland from the coastal margin was followed by valley widening, scarp retreat and pedimentation. |