Waterfall, gorges and interlocking spurs

• What are the two main features formed by rivers mentioned in the study material?

  Waterfalls and gorges
• How are waterfalls formed according to the study material?

  By a river flowing over hard and soft rock
• What happens to the softer rock when a river flows over it?

  It is eroded more than the hard rock
• What is created as water flows over the step formed by erosion?

  A steep drop called a waterfall
• What happens to the hard rock as erosion continues at a waterfall?

  It becomes undercut and collapses
• What is formed at the foot of the waterfall due to erosion?

  A deep plunge pool
• What process continues to occur over time at a waterfall?

  More undercutting causes more collapses
• What is left behind as a waterfall retreats?

  A steep-sided gorge
• What type of valleys are created in the upper course of a river?

  Steep-sided v-shaped valleys
• Why do rivers lack the power to erode laterally in their upper course?

  They primarily erode vertically
• What do the hillsides that interlock with each other resemble?

  They resemble a zip
• What are the processes involved in the formation of waterfalls and gorges?

  • River flows over hard and soft rock
  • Softer rock eroded by hydraulic action and abrasion
  • Step created as water flows over
  • Waterfall forms from steep drop
  • Hard rock undercut and collapses
  • Erosion creates deep plunge pool
  • Waterfall retreats, leaving steep-sided gorge
• What are interlocking spurs and how are they formed?

  • Formed in the upper course of a river
  • Vertical erosion creates steep-sided v-shaped valleys
  • Rivers wind around high hillsides
  • Hillsides interlock like a zip