Correct Option
The Himalayas are a prime example of young fold mountains, characterized by ongoing tectonic activity and rapid geomorphological processes. All the listed features are indicative of this geological youth and active orogeny.
- Deep gorges: These are formed by the rapid downward cutting action of rivers (fluvial incision) as the mountains are continuously uplifted. This indicates a young, tectonically active landscape where erosion has not yet reached a mature stage.
- U-turn river courses: Also known as syntaxial bends, these sharp turns in river paths are often a result of the complex folding and faulting associated with mountain building, where rivers are forced to adjust their courses around resistant rock structures or tectonic bends.
- Parallel mountain ranges: The Himalayas consist of several parallel ranges (e.g., Shiwaliks, Lesser Himalayas, Greater Himalayas) separated by major thrust faults. This arrangement is a direct consequence of the compressional forces involved in the collision of the Indian and Eurasian plates, leading to the folding and faulting of sedimentary rocks into distinct, aligned ranges.
- Steep gradients causing landsliding: The steep slopes, unconsolidated young sedimentary rocks, and ongoing seismic activity (due to active faulting and uplift) make the Himalayas highly susceptible to landslides. This instability is a hallmark of a geologically young and tectonically active mountain system.
Incorrect Options
Options (A), (B), and (C) are incorrect because they exclude one or more features that are direct evidence of the Himalayas' status as young fold mountains. All four listed characteristics are geological indicators of ongoing tectonic activity and the youthful stage of mountain building in the Himalayas.