--- title: "Physiographic and tectonic division of Nepal" subject: "Engineering Geology I" chapter: 7 key: "semester_3/engineering_geology_i:physiographic-and-tectonic-division-of" source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/physiographic-and-tectonic-division-of site: BCT Engineering --- # Physiographic and tectonic division of Nepal Engineering Geology I · Chapter 7: Geology of Nepal - Asked in: 2075 Chaitra, 2.5+2.5 marks - Video: [नेपाल का भूगोल | Geography of N | World Geography](https://www.youtube.com/watch?v=UuT2K1YgREE) — Satya - Vishal Gangwani - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/physiographic-and-tectonic-division-of - Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-7 ## Question How do you differentiate physiographic division and tectonic division of Nepal? Describe. ## 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. ## Answer **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 1. **Terai (Gangetic plain):** Quaternary alluvium. 2. **Sub-Himalaya (Siwalik zone):** Miocene to Pleistocene molasse sediments. 3. **Lesser Himalaya:** Precambrian to Palaeozoic low-grade metamorphic rocks and sediments. 4. **Higher Himalaya (Great Himalaya):** high-grade metamorphic rocks and granites. 5. **Tibetan-Tethys Himalaya:** Palaeozoic to Cretaceous fossiliferous marine sediments. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is the basis of physiographic division compared with tectonic division? A. Physiographic: structure and thrusts; tectonic: altitude B. Physiographic: landform, relief and altitude; tectonic: structure, rock type, age and bounding thrusts C. Both are based on rock age only D. Physiographic: rock age; tectonic: climate Answer: B. Physiographic division uses surface landform, relief and altitude; tectonic division uses geological structure and bounding thrusts or faults. (Key point: Basis of division) 2. How do the boundaries differ? A. Physiographic are sharp thrusts; tectonic are gradual B. Physiographic are gradual changes in relief; tectonic are sharp (MFT, MBT, MCT, STDS) C. Both are sharp D. Both are gradual Answer: B. Physiographic boundaries change gradually with relief while tectonic ones are sharp thrusts or faults. (Key point: Boundaries) 3. How many zones are there in each division? A. Physiographic five, tectonic six B. Physiographic six, tectonic five C. Both five D. Both six Answer: B. Nepal has six physiographic zones and five tectonic zones. (Key point: Number of zones) 4. Which division is mainly used for geology, engineering hazards and earthquakes? A. Physiographic division B. Tectonic division C. Neither D. Climatic division Answer: B. Tectonic division is used for geology, hazards and earthquakes; physiographic is used for climate, settlement and land use. 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