Observation

This question was fairly popular among the candidates and they performed averagely.
While many of the candidates who answered the question were able to list the landforms in the upper course of a river notably gorge, v-shaped valley, waterfall, rapids/cataracts, interlocking spurs, pot holes, wind gap, misfit, elbow of capture and plunge pool, many of them were unable to describe the characteristics and mode of formation of ox-bow lake using diagrams to aid their explanations. The characteristics of ox-bow lake that were to be described included:

-           landform of deposition by river
-           feature of lower course of a river
-           occurs in marshy areas
-           horse -shoe in shape
-           shallow convex bank
-           deep concave bank
-           called buyouts or cut offs
-           may dry up
-           Examples in Mississippi river, Mekong river, River Trente in Great Britain,
Muraine in Australia, etc.

            The mode of formation of an ox-bow lake that should have been described included:

• formed in the lower course of a river
• formed due to pronounced meanders
• erosion on the concave bank
• deposition on the convex bank
• neck becomes very narrow
• river breaks through the narrow neck during floods
• leads to deposition of sediment at the entrance of the loop.
• results in a cut off lake called oxbow lake.