NABTEB Geography 2024 Theory — Question 7

Model answer

(a) Three features found in the middle course of a river: - Meanders: Curved sections of the river channel formed by erosion and deposition. - Flood plains: Flat areas adjacent to the river, subject to periodic flooding. - Levees: Natural or artificial ridges along the river, formed by sediment deposition. (Also acceptable: terraces, oxbow lakes, point bars, braiding.) (b) A pothole is a rounded, bowl-shaped hollow eroded into the rocky bed of a river. Mode of formation: - Erosion: Potholes form when a rock surface is subjected to repeated erosion by water, which wears away the rock surface and creates a depression. - Abrasion: Sediment and debris (pebbles and stones) carried by the water act as abrasives, scouring the rock surface and deepening the depression as they are swirled around by turbulent flow (eddying). - Plucking: As the water flows, it may dislodge and remove fragments of rock, further enlarging the pothole. Characteristics of potholes: - They typically have a rounded, bowl-like shape, reflecting the erosive/swirling action of water and trapped stones. - They can range from small, shallow depressions to large, deep holes. - The sides of potholes are often steep and smooth, reflecting the erosive action of water. - The floor of a pothole is typically smooth and polished, reflecting the abrasive action of sediment and debris.