Which among the following statements provides the best evidence that a river is flowing through a rift valley?

The best evidence that a river flows through a rift valley is its inability to form a delta, resulting instead in an estuary. Rift valleys, such as those occupied by the Narmada and Tapi (Tapti) in India, are linear lowlands formed by tectonic plates pulling apart [t2, t7]. These valleys are characterized by steep, parallel escarpments and narrow paths that create high gradients [t2]. This steepness prevents the accumulation of sediment necessary for delta formation at the river's mouth, leading to the formation of an estuary where the river meets the sea [t2]. While the Chambal valley is known for badland topography due to soil erosion, and the Grand Canyon and Satkosia gorge are primarily products of vertical downcutting and erosional cycles rather than tectonic rifting [c3, c4, t2], the Tapi's lack of a delta is a direct consequence of its confinement within a rift valley [c2, t2].

Sources

1. [1] INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.) > Chapter 3: Drainage System > THE PENINSULAR DRAINAGE SYSTEM > p. 23
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 16: Fluvial Landforms and Cycle of Erosion > River Valley > p. 198
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 16: Fluvial Landforms and Cycle of Erosion > River Valley > p. 197