A section of the longitudinal course of a river from head to mouth, showing only vertical changes (Harmar and Clifford (2007) Geomorph. 84, 3–4). See Jain et al. (2006) Geomorph. 74, 1–4 on stream power plots along long profiles. The theoretically smooth curve shown by such a profile may be interrupted by breaks of slope which can result from bands of resistant rock or from rejuvenation (Larue (2008) Geomorph. 93, 3–4).