2.2.1: A river that has its water diverted into another river is referred to as a captured stream.

Here are the answers to the questions based on the provided sketches on river capture:

• 2.2.1: A river that has its water diverted into another river is referred to as a captured stream.
  • Answer: A
• 2.2.2: Rivers flowing over areas with a steep gradient and soft rock are more likely to be the captor stream, as these conditions favor rapid headward erosion.
  • Answer: C
• 2.2.3: Evidence that river capture has taken place in sketch B is that River Y has captured the headwaters of river X.
  • Answer: B
• 2.2.4: The cause of river capture, as shown in sketch B, is headward erosion by river Y. River Y has eroded backwards to breach the watershed and divert the flow of river X.
  • Answer: A