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Difficulty: HardLandform Evolution by Running Water and Underground Water

During stream piracy, an aggressive river tributary undergoes active headward erosion, breaching a watershed divide and intercepting the flow of a neighboring stream. Which landform is created in the abandoned valley immediately downstream of the elbow of capture?

  1. Wind gapAnswer
  2. B
    Oxbow lake
  3. C
    Knickpoint
  4. D
    Plunge pool

Answer

A wind gap is formed in the abandoned valley immediately downstream of the elbow of capture during river piracy.
When a river captures the upper waters of an adjacent stream, the valley downstream from the elbow of capture is deprived of its main water source. The dry gap or pass cut through the ridge where the original river used to flow is known as a wind gap.

Step-by-Step Solution

1
Analyze the geomorphic process described in the stem.
The process is stream piracy (river capture), where active headward erosion enables one stream to breach a watershed divide and divert another stream's flow.
Understanding stream piracy features requires identifying what happens at and downstream of the interception point (elbow of capture).
2
Identify the features associated with stream piracy.
The interception site is the elbow of capture; the diverted upper stream becomes the pirate stream; the stream below the elbow loses its headwaters and becomes a misfit stream; and the abandoned, dry valley pass downstream of the elbow forms a wind gap.
Landform classification in fluvial geomorphology relies on linking specific river processes to their resultant morphological features.

Key Concept

Stream Piracy (River Capture) and Associated Fluvial Landforms
Estimated Time:1m 15s
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Topics

Landform Evolution by Running Water and Underground Water

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