---
title: "Geological work of wind and its landforms"
subject: "Engineering Geology I"
chapter: 6
key: "semester_3/engineering_geology_i:geological-work-of-wind-and"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/geological-work-of-wind-and
site: BCT Engineering
---

# Geological work of wind and its landforms

Engineering Geology I · Chapter 6: Physical Geology

- Asked in: 2081 Baisakh (new course), 3 marks; 2081 Bhadra, 2.5 marks; 2074 Chaitra, 4 marks; 2073 Shrawan, 4 marks; 2076 Chaitra, 1.5 marks; 2076 Asoj, 2.5 marks (asked 6 times)
- Video: [Geological Work of Wind](https://www.youtube.com/watch?v=JvXL3Aw5szc) — Deva Ram
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/geological-work-of-wind-and
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-6

## Question

Describe the geological work of wind and the (erosional and depositional) landforms developed by it.

## Short answer

Wind erodes by deflation and abrasion, transports by saltation and suspension, and deposits sand as dunes (barchan, transverse) and silt as loess. Erosional landforms include mushroom rocks, yardangs, deflation hollows, and ventifacts.

## Answer

The **geological work of wind** is called aeolian action. It is strong in deserts and dry coasts where there is little vegetation, loose sand and strong wind. It has three parts:

1. **Erosion**
   - *Deflation:* lifting and removal of loose fine particles.
   - *Abrasion (sand blasting):* grains carried by wind cut and polish rocks.
   - *Attrition:* grains wear each other down to rounded, frosted shapes.
2. **Transportation:** fine dust moves in **suspension** for long distances; sand moves by **saltation** (bouncing, the main way) and coarse grains by **surface creep**.
3. **Deposition:** when the wind speed falls or hits an obstacle.

#### Erosional landforms
- **Deflation hollows (blowouts):** wind lifts loose fine particles and lowers the ground, e.g. Qattara depression.
- **Mushroom (pedestal) rocks:** sand abrades the base of a rock more than its top.
- **Yardangs:** streamlined ridges of rock parallel to the wind.
- **Ventifacts:** pebbles with polished, flat faces cut by sand blast.
- **Zeugen:** tabular ridges of hard rock over softer layers.
- **Desert pavement:** gravel left after fine particles are blown away.
- **Inselbergs:** isolated residual hills.

#### Depositional landforms
- **Sand dunes:** barchan (crescent shaped, horns point downwind), transverse, longitudinal (seif) and parabolic dunes.
- **Ripple marks:** small ridges on sand surfaces.
- **Loess:** thick deposit of fine, windblown silt, uniform, porous and buff in colour (northern China). It collapses when wetted, which matters in foundation design.

## Check yourself

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

1. What is deflation?
   A. Cutting of rock by grains
   B. Wearing down of grains by each other
   C. Deposition of dunes
   D. Lifting and removal of loose fine particles by wind
   Answer: D. Abrasion cuts rocks; attrition wears grains. (Key point: Deflation)

2. How does sand mainly move by wind?
   A. Saltation
   B. Suspension
   C. Solution
   D. Surface creep only
   Answer: A. Sand bounces; dust is suspended. (Key point: Main transport)

3. Why do mushroom rocks form?
   A. Water dissolves the top
   B. Sand abrades the base more than the top
   C. Ice carves the base
   D. Deposit builds the top
   Answer: B. Sand is carried near the ground. (Key point: Mushroom rock)

4. What is a problem of loess in foundations?
   A. It is too hard
   B. It is impermeable gravel
   C. It collapses when wetted
   D. It floats
   Answer: C. Loess is porous and collapses on wetting. (Key point: Loess)

## Related in Engineering Geology I

- [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×
- [Geological work of running water and its landforms](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Ageological-work-of-running-water) — Engineering Geology I, chapter 6, asked 5×
- [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
- [Geological agents and their geological work](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Ageological-agents-and-their-geological) — Engineering Geology I, chapter 6, asked 7×