- 2075 Chaitra · 2.5+2.5 marks
Physiographic and tectonic division of Nepal
Short answer
Physiographic division classifies Nepal by landform and altitude (Terai, Siwalik, Mahabharat, Midland, Higher Himalaya, Inner Himalaya), with gradual boundaries. Tectonic division is based on rock types, ages, and bounding thrusts (MFT, MBT, MCT, STDS), dividing Nepal into Terai, Sub-Himalaya, Lesser Himalaya, Higher Himalaya, and Tethys zones.
How do you differentiate physiographic division and tectonic division of Nepal? Describe.
Physiographic division is based on the surface landform, relief and altitude. Tectonic division is based on geological structure, i.e. rock types, age and bounding thrusts or faults.
| Point | Physiographic division | Tectonic division |
|---|---|---|
| Basis | Landform, altitude, climate | Structure, lithology, major thrusts |
| Boundaries | Gradual, changes in relief | Sharp: MFT, MBT, MCT, STDS |
| Zones | Terai, Siwalik (Churiya), Mahabharat, Midland, Higher Himalaya, Inner Himalaya | Terai, Sub-Himalaya (Siwalik), Lesser Himalaya, Higher Himalaya, Tethys Himalaya |
| Number | Six | Five |
| Use | Climate, settlement, land use | Geology, engineering hazards, earthquakes |
| Age relation | Not considered | Rock age is distinct in each zone |
Physiographic zones
| Zone | Approx. altitude | Main features |
|---|---|---|
| Terai plain | 60-300 m | Flat alluvial plain, Indo-Gangetic plain |
| Siwalik (Churiya) range | 300-1500 m (up to 2000 m) | Youngest, low hills of weak rocks, with Dun valleys |
| Mahabharat range | 1500-2700 m (up to 3000 m) | Steep, continuous ridge of the Lesser Himalaya |
| Midlands (Pahad), Fore Himalaya | 800-2500 m | Hills, river valleys and basins (Kathmandu, Pokhara) |
| Higher (Great) Himalaya | 4000-8848 m | Snow-capped peaks, glaciers, Mt. Everest |
| Inner (Trans, Tibetan-Tethys) Himalaya | 2500-5000 m | Dry, rain-shadow region north of the Great Himalaya |
Tectonic zones
- Terai (Gangetic plain): Quaternary alluvium.
- Sub-Himalaya (Siwalik zone): Miocene to Pleistocene molasse sediments.
- Lesser Himalaya: Precambrian to Palaeozoic low-grade metamorphic rocks and sediments.
- Higher Himalaya (Great Himalaya): high-grade metamorphic rocks and granites.
- Tibetan-Tethys Himalaya: Palaeozoic to Cretaceous fossiliferous marine sediments.
✓ Answer checked by Claude Opus 5.5 (high effort)
Related questions
- Physiographic division of the Nepal Himalaya · Engineering Geology I, chapter 7 · asked 7×
- Tectonic division and Lesser Himalaya geology · Engineering Geology I, chapter 7
- Physiographic division; Siwalik and Higher Himalaya · Engineering Geology I, chapter 7
- Tectonic divisions of the Nepal Himalaya · Engineering Geology I, chapter 7 · asked 4×
- Tectonic divisions with sketch and problems · Engineering Geology I, chapter 7 · asked 4×
- Engineering geological problems in tectonic divisions · Engineering Geology I, chapter 7 · asked 2×
- Restoring vs non-restoring division · Computer Organization and Architecture, chapter 5 · asked 5×