What is the process called that refers to a renewal of erosive activity in an older stage of a river?

The process referred to in the question is known as rejuvenation. This occurs when a river experiences a renewed phase of erosive activity after a period of relative stability. Rejuvenation typically happens due to changes in base level, such as a drop in sea level or uplift of the land, which allows the river to erode more deeply into its valley and landscape.

During this process, the river can change its profile, becoming steeper in some areas and eroding sediment more vigorously. This leads to the formation of features like entrenched meanders or river terraces as the landscape adjusts to the new erosive forces at play. Understanding rejuvenation helps illustrate the dynamic nature of river systems and how they evolve over geological time.