River Features - Geo for CXC

Overview

• A river valley is divided into three sections:
  • Upper Course
  • Middle Course
  • Lower Course
• Each section has distinct river features due to differences in gradient and valley shape.

Upper Course Features

• Characteristics:
  • Closest to the source
  • Steep gradient
  • Small, fast-flowing river

Key Features

• V-shaped Valleys:

  • Formed by vertical erosion
  • Deep valleys with steep sides

• Interlocking Spurs:

  • Formed as river winds around obstacles
  • High land ridges projecting towards the river

• Waterfalls:

  • River plunges over rock face
  • Commonly formed where river crosses hard rock

• Gorges:

  • Formed as waterfalls retreat upstream
  • Narrow, steep-sided features

• Rapids:

  • Fast water flow over steep, rough river bed
  • Turbulent water often due to alternating rock bands

Middle Course Features

• Characteristics:
  • Less steep gradient
  • Wider, more open river
  • Increased lateral erosion and deposition

Key Features

• Meanders:

  • Bends in the river

• River Cliffs and Slip-off Slopes:

  • Outside banks undercut, forming cliffs
  • Inside banks slow water, depositing sediments creating slip-off slopes

Lower Course Features

• Characteristics:
  • Nearest to the sea
  • Gentle gradient
  • Slow-flowing, large volume river
  • Predominant deposition

Key Features

• Flood Plain:

  • Wide, flat valley floor deposits from flooding

• Ox-bow Lakes:

  • Crescent-shaped lakes from abandoned meanders
  • Formed when river cuts a new, shorter course

• Levees:

  • Natural embankments from repeated flood deposits

• Braiding:

  • River divides into multiple channels separated by sediment bars

• Deltas:

  • Flat land built from river sedimentation at sea
  • Conditions favoring delta formation include large sediment load, calm sea, shallow sea, slow river flow, and small tidal range

Example:

• Nile Delta:
  • Formed as Nile dumps sediment into the Mediterranean Sea

These features illustrate how river dynamics shape landscapes through erosion and deposition at various stages of a river's course.