Correct Option
The correct option is (c) 1 and 3 only.
Explanation
An Ox-bow lake is a crescent-shaped water body formed alongside a winding river. It represents a former meander loop that has been isolated from the main channel due to the dynamic processes of erosion and deposition in a river's floodplain.
Statement-wise Analysis
- Statement 1 is Correct: As a river meanders across a floodplain, lateral erosion accentuates the curvature of the loops. Eventually, the neck of the meander becomes extremely narrow. During periods of high discharge or flooding, the river cuts through this narrow neck to take a straighter course, abandoning the loop. This isolated loop forms the ox-bow lake.
- Statement 2 is Incorrect: Ox-bow lakes are characteristic features of the middle or lower course of a river (plains), where the river flows over a gentle gradient and lateral erosion dominates. They are not found in the mountains (upper course), where vertical erosion is dominant and features like V-shaped valleys, gorges, and waterfalls are formed. While the cut-off process involves erosion, the feature itself is associated with the depositional environment of floodplains.
- Statement 3 is Correct: Because the formation process involves the river abandoning or "cutting off" a meander loop from the active channel, these water bodies are technically referred to as cut-off lakes. In some regions, they are also known as bayous.
Key Takeaway
Ox-bow lakes are features of the mature or old stage of a river, found in floodplains. They result from the cut-off of meanders, a process driven by lateral erosion at the meander neck and subsequent deposition sealing the loop.