A break in a hill slope where it discontinuously steepens is referred to as a knickpoint or scarp, a standard term in geomorphology describing abrupt changes in river profiles or topography.
The claim provides standard geomorphological definitions for a knickpoint or scarp as a break or steepening in slope/profile. Retrieved literature in geomorphology (such as papers 1 and 5) discusses knickpoints and scarps in the context of bedrock channels and slope discontinuities, supporting the statement. No papers refute the claim.