1932 Bull. Geol. Soc. Amer. 43 416 If one convex nick can not be produced in the profile of a stream that is eroding its valley in an enlarging dome of continuously accelerated upheaval, all the less can a series of nicks be produced.

1941 C. A. Cotton Landscape xx. 233 Even where nicks occur at resistant outcrops, this is quite commonly a result merely of retardation at such points of headward erosion due to rejuvenation. The most widely accepted explanation of nicks in valley profiles is that they are the effects of successive lowerings of base-level.

1970 I. Cornwall Ice Ages i. 35 At the point where renewed erosion begins there will be a sharp increase in rate of fall, showing a ‘knick’, or downward break in gradient.

1936 Zeitschr. f. Geomorphol. IX. 132 Massive rocks, on weathering, produce steep mountain slopes because of their widely spaced joints. They are also characterized by a relatively sharp ‘Knick’, whereas in the same area more closely jointed rocks have lower slopes and there is a more gradual transition into the pediment at the base.

1952 Ann. Assoc. Amer. Geographers XLII. 305 Johnson..pointed to the sharp angle (knick) between pediment and inselberg as an indication that lateral corrosion and not weathering-retreat is the cause of destruction of the feature.

1963 D. W. Humphries & E. E. Humphries tr. H. Termier & G. Termier Erosion & Sedimentation ii. 36 Pediments are surfaces cut into hard rocks at the foot of mountains which they continue to erode. At their highest point, they join the mountain side at a break of slope called a ‘knick’.