--- title: "Tectonic divisions of the Nepal Himalaya" subject: "Engineering Geology I" chapter: 7 key: "semester_3/engineering_geology_i:tectonic-divisions-of-the-nepal" source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/tectonic-divisions-of-the-nepal site: BCT Engineering --- # Tectonic divisions of the Nepal Himalaya Engineering Geology I · Chapter 7: Geology of Nepal - Asked in: 2076 Asoj, 4 marks; 2078 Bhadra, 3 marks; 2081 Baisakh (new course), 3 marks; 2066 Bhadra (old course), 5 marks (asked 4 times) - Video: [Himalaya's Fold mountains and Thrust boundaries explained with animation (part 2/3) | UPSC](https://www.youtube.com/watch?v=mF58L2J0FK4) — Zeta Axis (UPSC-SSC) - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/tectonic-divisions-of-the-nepal - Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-7 ## Question Describe the tectonic divisions (subdivisions) of the Nepal Himalaya. ## Short answer Nepal is divided into five tectonic zones separated by thrusts: Terai (Quaternary alluvium), Sub-Himalaya (Siwalik molasse), Lesser Himalaya (low-grade metamorphics), Higher Himalaya (high-grade gneiss, granites), and Tibetan-Tethys Himalaya (fossiliferous marine sediments). Key boundaries are MFT/HFT, MBT, MCT, and STDS. ## Answer From south to north, Nepal is divided into five **tectonic zones**, separated by major thrusts and faults (discontinuities): ```text S N Terai | Sub-Him | Lesser Him | Higher Him | Tethys |(Siwalik)| | | MFT/HFT MBT MCT STDS ``` 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. **Boundaries (major discontinuities)** - **Main Frontal Thrust (MFT) / Himalayan Frontal Thrust (HFT):** between the Terai and Siwalik. - **Main Boundary Thrust (MBT):** between the Siwalik and Lesser Himalaya. - **Main Central Thrust (MCT):** between the Lesser and Higher Himalaya. - **South Tibetan Detachment System (STDS):** between the Higher Himalaya and the Tethys zone. #### Short notes on the zones - **Terai:** Quaternary alluvium; flat, flood-prone. - **Siwalik:** weak sandstone, mudstone and conglomerate. - **Lesser Himalaya:** phyllite, slate, quartzite, limestone, dolomite. - **Higher Himalaya:** gneiss, schist, migmatite and granite. - **Tethys:** fossiliferous limestone, shale, sandstone. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Nepal is divided into how many tectonic zones? A. Three B. Five C. Four D. Seven Answer: B. Terai, Sub-Himalaya, Lesser, Higher and Tethys Himalaya. (Key point: Number of zones) 2. The Main Boundary Thrust lies between: A. Terai and Siwalik B. Lesser and Higher Himalaya C. Siwalik and Lesser Himalaya D. Higher Himalaya and Tethys Answer: C. MFT separates Terai and Siwalik; MCT separates Lesser and Higher. (Key point: MBT) 3. The Main Central Thrust separates: A. Terai from Siwalik B. Siwalik from Lesser Himalaya C. Higher Himalaya from Tethys zone D. Lesser Himalaya from Higher Himalaya Answer: D. STDS bounds the Higher Himalaya and Tethys zone. (Key point: MCT) 4. The Higher Himalaya consists mainly of: A. High-grade metamorphic rocks and granites B. Quaternary alluvium C. Miocene molasse D. Fossiliferous marine sediments Answer: A. Gneiss, schist, migmatite and granite. (Key point: Higher Himalaya rocks) 5. Tethys Himalaya rocks are: A. Quaternary alluvium B. Palaeozoic to Cretaceous fossiliferous marine sediments C. Precambrian low-grade metamorphic rocks D. Granite intrusions only Answer: B. Limestone, shale and sandstone are typical. (Key point: Tethys zone) ## Related in Engineering Geology I - [Engineering geological problems in tectonic divisions](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aengineering-geological-problems-in-tectonic) — Engineering Geology I, chapter 7, asked 2× - [Tectonic division and Lesser Himalaya geology](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atectonic-division-and-lesser-himalaya) — Engineering Geology I, chapter 7 - [Tectonic divisions with sketch and problems](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atectonic-divisions-with-sketch-and) — Engineering Geology I, chapter 7, asked 4× - [Discontinuities and engineering problems in Nepal Himalaya](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Adiscontinuities-and-engineering-problems-in) — Engineering Geology I, chapter 7 - [Physiographic division of the Nepal Himalaya](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aphysiographic-division-of-the-nepal) — Engineering Geology I, chapter 7, asked 7× - [Physiographic and tectonic division of Nepal](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aphysiographic-and-tectonic-division-of) — Engineering Geology I, chapter 7 ## Related in other subjects - [Major discontinuity systems of Nepal Himalaya](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Anepal-discontinuity-systems) — Engineering Geology II, chapter 2, asked 12× - [Why Nepal Himalaya is landslide-prone](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Anepal-landslide-prone) — Engineering Geology II, chapter 5 - [Factors causing hazards in Nepal Himalaya](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Anepal-himalaya-hazard-factors) — Engineering Geology II, chapter 5