---
title: "Erosional features of glacier and underground water"
subject: "Engineering Geology I"
chapter: 6
key: "semester_3/engineering_geology_i:erosional-features-of-glacier-and"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/erosional-features-of-glacier-and
site: BCT Engineering
---

# Erosional features of glacier and underground water

Engineering Geology I · Chapter 6: Physical Geology

- Asked in: 2072 Chaitra, 3 marks
- Video: [Erosional Landforms made by Glaciers - Landforms and Their Evolution | Class 11 Geography | NCERT](https://www.youtube.com/watch?v=Svp-6cXYrgY) — Smart Tute
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/erosional-features-of-glacier-and
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-6

## Question

Mention the erosional features of glacier and underground water.

## Short answer

Glacial erosion produces cirques, arêtes, horns, U-shaped valleys, hanging valleys, fjords, and roche moutonnée. Underground water dissolves limestone to form sinkholes, caves, sinking streams, lapies, uvalas, and poljes in karst topography.

## Answer

#### Glacier
- **Cirque (corrie):** armchair-shaped hollow at the head of a glacier, made by plucking and abrasion; a lake in it is a *tarn*.
- **Arête:** knife-edge ridge between two cirques.
- **Horn (pyramidal peak):** sharp peak left when cirques cut back on all sides, e.g. Matterhorn.
- **U-shaped valley (glacial trough):** the glacier widens and deepens a river valley.
- **Hanging valley:** side valley left high above the main trough; it often ends in a waterfall.
- **Fjord:** glacial trough drowned by the sea.
- **Roche moutonnée, striations and grooves:** smoothed and scratched bedrock surfaces.
- **Rock basins and tarns.**

#### Underground water
Groundwater erodes mostly by **solution**, working on soluble rocks (limestone, dolomite, gypsum). The landscape is called **karst topography**. Features:

- **Sinkholes (dolines):** closed depressions made by dissolution or by collapse of a cave roof.
- **Caves and caverns:** underground hollows enlarged along joints and bedding planes.
- **Sinking streams and underground rivers**, **springs**.
- **Lapies (karren):** grooves and ridges on exposed limestone.
- **Uvala and polje:** large, compound sinkholes and wide valley-like basins.
- **Natural bridges** and **dry valleys**.

## Check yourself

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

1. U-shaped valleys form when:
   A. River cuts vertically
   B. Wind erodes
   C. Glacier widens and deepens a river valley
   D. Sea floods
   Answer: C. Rivers give V-shapes. (Key point: U-valley)

2. A hanging valley is:
   A. Valley drowned by sea
   B. Valley under ice
   C. Deep gorge
   D. Side valley left high above the main trough, often with a waterfall
   Answer: D. Fjords are drowned troughs. (Key point: Hanging valley)

3. Groundwater erodes mainly by:
   A. Solution of soluble rocks
   B. Plucking
   C. Abrasion
   D. Deflation
   Answer: A. Limestone, dolomite, gypsum. (Key point: Groundwater erosion)

4. Landscape produced by solution is:
   A. Glacial trough
   B. Karst topography
   C. Delta
   D. Dune field
   Answer: B. With sinkholes, caves and lapies. (Key point: Karst)

## Related in Engineering Geology I

- [Erosional features of underground water](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aerosional-features-of-underground-water) — Engineering Geology I, chapter 6
- [Erosional and depositional features of river and glacier](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aerosional-and-depositional-features-of) — Engineering Geology I, chapter 6, asked 2×
- [Erosional feature of running water and wind](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aerosional-feature-of-running-water) — Engineering Geology I, chapter 6
- [Erosional and depositional landforms of glaciers](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aerosional-and-depositional-landforms-of) — Engineering Geology I, chapter 6, asked 3×

## Related in other subjects

- [Underground water tank: excavation, brick, plaster](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Aug-tank-g-brick-plaster) — Estimating and Costing, chapter 6