WAEC Geography 2023 Theory — Question 11

Model answer

(a) Processes of river transportation: traction; saltation; suspension; solution. (b) Characteristics of the middle course of a river: the river channel becomes wider than in the upper course; the velocity of flow reduces compared to the upper course; both erosion and deposition occur; meanders begin to form; the valley becomes broader with a flatter gradient. (c) Formation of interlocking spurs: Interlocking spurs are formed in the upper section of a river. There is the presence of a highland projecting into the course of the river with alternate bands of hard and soft rocks, and the presence of obstacles such as hard rocks. Vertical erosion dominates at this section, and the river meanders as it takes its course along the easiest path down its slope. Soft rocks are eroded by the fast-flowing river; as a result, the river tends to go round the hard rock. The fast-flowing river takes a winding course and cuts deep valleys; as this continues, the bends in the river become more pronounced as the river flows faster. This erodes the concave sides, causing the highlands to project into the floor of the river as spurs. Little erosion occurs at the convex side; materials eroded from the concave bank are deposited at the convex bank. Further erosion causes the alternate spurs on the bank to project into the concave banks of the river, which eventually interlock with each other to form features called interlocking spurs.