In the valleys, from the initial stage to the development, changes also occur in the surface position. Considering the change in base – surface as the basis.
The valleys are classified into the following parts:
1. Drowned Valley
2. Rejuvenated Valley
1. Drowned Valley: A submerged coastal valley formed as a result of rise in water level of a ocean or lake or sinking down of proximal place is called Drowned Valley.
2. Rejuvenated Valley: On the fall in sea level, river rejuvenation involves a renewed period of vertical erosion to achieve a new and lower base level, which is called the Rejuvenated Valley