The channel or valley formed by fluvial systems that extend their channels basinward and erode into underlying strata in response to a relative fall in sea level. Incised valleys can be up to several hundred feet deep and range in width from a half mile to many tens of miles.
Timing of the incision of the incised valley will often be within the Falling Stage Systems Tract, while the fill of the incision will tend to occur during the following Lowstand Systems Tract to be capped by a Trangressive Surface.

Coe, Angela, Dan Bosence, Kevin Church, Steve Flint, John Howell and Chris Wilson, (2002) "The Sedimentary Record of Sea Level Change" ,Cambridge University Press, 288 pp.