Rivers

• • A river's long profile shows how the steepness of a river changes over the course of the river.
  • The course of a river is the path that the river takes from its source.
  • A river's course is split into the upper, middle, and lower course.
  • The gradient decreases (the slope becomes more gentle) as the river moves from its upper course towards its lower course.

  
• • In the upper course, erosion dominates over deposition. This means that:
  • The valley is steep-sided and shaped like a V.
  • The channel that the water flows through is narrow and not very deep.

  
• • In the middle course, neither erosion nor deposition is particularly dominant. This means that:
  • The valley has a gentle slope.
  • The channel is wider than at the upper course. The channel is also deeper than at the upper course.

  
• • In the lower course, deposition dominates over erosion. This means that:
  • The valley is wide and flat.
  • The channel is wide and deep.

  
• • Vertical erosion makes the river valley deeper.
  • Vertical erosion dominates in the upper course.
  • This is because high levels of turbulence make rough and angular particles drag along the river bed.
• • Lateral erosion makes the river valley wider.
  • Lateral erosion dominates in the lower course and middle course.