Arrange the following stages of river capture (stream piracy) in their correct chronological sequence from the initial headward erosion to the final landform development.
- 1A stream with a steeper gradient or softer bedrock actively erodes headward toward a neighbouring watershed divide.
- 2The capturing stream breaches the watershed divide and intercepts the headwaters of the less powerful stream.
- 3The upper course of the captured river is diverted into the capturing river channel at a sharp bend called the elbow of capture.
- 4The trunk valley downstream of the diversion point loses its headwaters, leaving a dry valley forming a wind gap and a misfit stream.
Answer
The correct sequence begins with headward erosion toward the watershed divide, followed by breaching the divide to intercept the weaker stream, the diversion of flow creating an elbow of capture, and finally the formation of a wind gap and misfit stream downstream.
River capture begins when a stream with higher energy or a steeper gradient erodes headward into a watershed divide. Once the divide is breached, the stream intercepts the headwaters of a neighbouring channel. The diverted water creates a sharp bend known as an elbow of capture, while the dry valley below the point of capture becomes a wind gap containing a reduced misfit stream.
Step-by-Step Solution
Key Concept
River Capture (Stream Piracy) and Drainage Evolution