---
title: "Define weathering and its controlling factors"
subject: "Engineering Geology I"
chapter: 6
key: "semester_3/engineering_geology_i:define-weathering-and-its-controlling"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/define-weathering-and-its-controlling
site: BCT Engineering
---

# Define weathering and its controlling factors

Engineering Geology I · Chapter 6: Physical Geology

- Asked in: 2075 Chaitra, 1+3 marks; 2076 Chaitra, 1.5 marks; 2073 Shrawan, 1 marks; 2072 Chaitra, 2 marks (asked 4 times)
- Video: [2.1 | Video 2 | Weathering | Controlling Factors | Types & Geological Importance](https://www.youtube.com/watch?v=xa1Dvhymk0o) — e-GyanSetu
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/define-weathering-and-its-controlling
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-6

## Question

Define weathering. Describe the factors that affect weathering of rocks.

## Short answer

Weathering is the in-place disintegration and decomposition of rocks. Factors controlling it include climate, rock type and mineral composition, rock structure, topography, vegetation, time, and grain size/porosity.

## Answer

**Weathering** is the in-place disintegration (physical) and decomposition (chemical) of rocks at or near the earth's surface by the action of atmospheric agents, water and organisms, without transport of the material.

#### Factors controlling weathering
1. **Climate:** temperature and rainfall. Frost action dominates in cold areas; chemical weathering in hot, humid areas.
2. **Rock type and mineral composition:** quartz is very resistant; olivine, feldspar and calcite weather quickly.
3. **Rock structure:** joints, bedding and faults let water and air enter.
4. **Topography (relief):** steep slopes remove debris and expose fresh rock; gentle slopes keep a thick soil cover.
5. **Vegetation and organisms:** roots, bacteria and humic acids speed up weathering, but dense cover also protects the surface.
6. **Time:** the longer the exposure, the deeper the weathering.
7. **Grain size and porosity:** coarse or porous rocks have more surface for reaction.

## Check yourself

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

1. Weathering is best defined as:
   A. Removal of material by rivers
   B. In-place disintegration and decomposition of rocks at the surface without transport
   C. Melting of rocks
   D. Deposition of sediments
   Answer: B. No transport is involved. (Key point: Definition)

2. Which climate favours chemical weathering over frost action?
   A. Cold
   B. Hot desert
   C. Hot humid
   D. Polar
   Answer: C. Frost action dominates cold areas; chemical weathering is fastest in hot, humid areas. (Key point: Climate)

3. Which mineral is very resistant to weathering?
   A. Olivine
   B. Feldspar
   C. Calcite
   D. Quartz
   Answer: D. Olivine, feldspar and calcite weather quickly. (Key point: Rock type)

4. Why do joints and faults speed weathering?
   A. They let water and air enter the rock
   B. They make rock harder
   C. They stop water entering
   D. They cool the rock
   Answer: A. Openings admit agents of weathering. (Key point: Structure)

## Related in Engineering Geology I

- [Chemical versus physical weathering; factors](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Achemical-versus-physical-weathering-factors) — Engineering Geology I, chapter 6

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