---
title: "Dun valley and midland lithology and altitude"
subject: "Engineering Geology I"
chapter: 7
key: "semester_3/engineering_geology_i:dun-valley-and-midland-lithology"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/dun-valley-and-midland-lithology
site: BCT Engineering
---

# Dun valley and midland lithology and altitude

Engineering Geology I · Chapter 7: Geology of Nepal

- Asked in: 2072 Chaitra, 2 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/dun-valley-and-midland-lithology
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-7

## Question

Describe the lithology and altitude range of the Dun valley and midland.

## Short answer

Dun valleys: 200-700 m altitude; unconsolidated alluvial and fluvial gravel, sand, silt, clay, colluvium. Midland: 800-2500 m (ridges to 3000 m); phyllite, slate, schist, quartzite, limestone, dolomite, gneiss, granite with lacustrine/fluvial basin sediments.

## Answer

| Zone | Altitude | Lithology |
|---|---|---|
| Dun valleys | About 200-700 m | Unconsolidated alluvial and fluvial gravel, sand, silt and clay, with colluvium from the surrounding hills |
| Midland | About 800-2500 m (up to 3000 m on the ridges) | Phyllite, slate, schist, quartzite, limestone, dolomite, gneiss and granite; basins with lacustrine and fluvial sediments |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What fills the Dun valleys?
   A. Hard granite
   B. Unconsolidated alluvial and fluvial gravel, sand, silt and clay with colluvium
   C. Marine limestone
   D. Metamorphic gneiss
   Answer: B. Dun valleys are filled with unconsolidated alluvial and fluvial sediments plus colluvium from surrounding hills. (Key point: Dun valley lithology)

2. What is the approximate altitude of the Dun valleys?
   A. About 200-700 m
   B. About 800-2500 m
   C. About 4000-8848 m
   D. About 2500-5000 m
   Answer: A. Dun valleys lie at about 200-700 m, lower than the midland at 800-2500 m. (Key point: Dun altitude)

3. Which describes the midland zone?
   A. Phyllite, slate, schist, quartzite, limestone, dolomite, gneiss and granite, with lacustrine basins
   B. Only Quaternary gravel
   C. Only fossiliferous shale
   D. Only snow and glacier
   Answer: A. The midland (800-2500 m) has Lesser Himalayan rocks and basins with lacustrine and fluvial sediments. (Key point: Midland lithology)

## Related in Engineering Geology I

- [Altitude and lithology of Churiya, Fore and Trans Himalaya](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aaltitude-and-lithology-of-churiya) — Engineering Geology I, chapter 7