Question

Which of the following landforms is formed in the upper course of the river?
A. Estuary
B. Delta
C. Alluvial fans
D. Waterfalls

Answer 1

Hint: The upper Course of the river (which is also known as the stage of youth) begins at the source of the river near the watershed, which is probably the crest of a mountain range. The river is very swift and it descends towards the steep slopes, and the predominant action of the river causes vertical erosion.

Complete answer:
The valley developed in these regions as the river moves through the upper course is deep, narrow, and distinctively V-shaped. Down-cutting takes place so rapidly that vertical erosion cannot keep pace. Where the rocks are very resistant, the valleys are narrow and the sides are steep that gorges, spurs, rapids, cataracts, and waterfalls are formed.
Because of the unequal resistance of hard and soft rocks traversed by a river, the outcrop of a band of hard rock may cause a river to ‘jump’ or ‘fall’ downstream. When rivers flow down in a sudden fall of some height, they are known as waterfalls. Waterfalls are formed when a river flows into soft rock after flowing over hard rock. Niagara Falls which is 167 feet high is an example of such a waterfall.
So, the correct answer is Option D.

Note: Estuary, delta, and alluvial fans are formed at the mouth of the river which is also known as the lower or plain course (stage of old age). Waterfalls are formed in the upper stages of a river. They occur where a stretch of hard rock overlies a softer rock. Falling water and rock particles erode the soft rock below the waterfall, creating plunge pools e.g. River Congo.