Knickpoint: Definition from Answers.com

The Horseshoe Falls, one of the three Niagara Falls. The falls are a knickpoint, formed by slower erosion above the falls than below.

A knickpoint is a term in geomorphology to describe a location in a river or channel where there is a sharp change in channel slope, such as a waterfall or lake, resulting from differential rates of erosion above and below the knickpoint. Differential rates of erosion can result from a change in the lithology of the river channel. Sharp changes in channel slope caused by faulting or in-channel construction are not considered knickpoints.

Knickpoints can also be caused by a change in base level. When a river is rejuvenated (that is, has a negative change in base level, the sea level falls), the long profile is lengthened as land rises from the sea. This increases the gradient of the long profile and causes the river to gain more erosive energy. A knickpoint marks the position of the former base level.

The river, having gained more potential energy due to gravity, will then proceed to work the knickpoints out of its system by either erosion (in the case of waterfalls) or deposition (in the case of lakes) in order for the river to reattain its smooth concave graded profile.

As is observed for many major waterfalls, knickpoints migrate upstream due to bedrock erosion.^[1]

References

^ Paul Bierman, Milan Pavich, E-an Zen, and Marc Caffee, Determining Rates and Patterns of Bedrock Incision by Large Rivers

v • d • e River morphology

Large-scale features	Drainage basin • Drainage network • Strahler number (stream order) • River valley • River delta

Alluvial rivers	Meander • Point bar • Cut bank • Riffle • Stream pool • Braided river • Bar (river morphology) • Anabranch • River bifurcation • River channel migration • Oxbow lake • Floodplain • Riparian corridor • Avulsion (river) • Mouth bar

Bedrock river	Canyon • Knickpoint • Plunge pool • Bedrock erosion

Bedforms	Lower plane bed • Current ripple • Dune • Upper plane bed • Antidune

Regional processes	Aggradation • Degradation (geology) • Base level • Erosion and tectonics

Mechanics	Playfair's Law • Hack's law • Sediment transport • Water erosion • Deposition (geology) • Exner equation

Category · Portal

This geology article is a stub. You can help Wikipedia by expanding it.

This article about geography terminology is a stub. You can help Wikipedia by expanding it.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Donate to Wikimedia

	What is knickpoint waterffalls?
	Does River Nore and river barrow for knickpoints and paired terraces?

		Sci-Tech Dictionary. McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved. Read more
		Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Knickpoint". Read more