Question

a deep narrow opening formed by the river in the upper course

Answer 1

Upper course features. As the river moves through the upper course it cuts downwards. The gradient here is steep and the river channel is narrow. Verticalerosion in this highland part of the river helps to create steep-sided V-shaped valleys, interlocking spurs, rapids, waterfalls and gorges.
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Answer 2

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As the river moves through the upper course it cuts downward. The gradient here is steep and the river channel is narrow. Vertical erosion in this highland part of the river helps to create steep-sided V-shaped valleys, interlocking spurs, rapids, waterfalls and gorges
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