The entire path of the river from source to mouth is divided into three courses.
a. The upper course: It is near the source of a river and is normally found in mountainous areas. Here erosional work is dominant, because the river flows I steep slopes with great velocity. This stage of the river course is known as ‘Young Stage’.
b. The Middle course: The middle course begins when the river enters the plateau and plains from the mountains the dominant work of the river in this stage is transportation. This stage of the river course is called ‘Mature stage’.
c. The lower course: It is the plain course of a river neat its mouth. In the lower course the slope is very gentle, the valley is broad, the speed of the river is very slow, and hence deposition work is dominant. This stage f the river is known as ‘Old Stage’.
