---
title: "Residual and transported soils"
subject: "Soil Mechanics"
chapter: 1
key: "semester_4/soil_mechanics:residual-transported-soils"
source: https://www.bctengineer.com/q/semester_4/soil_mechanics/residual-transported-soils
site: BCT Engineering
---

# Residual and transported soils

Soil Mechanics · Chapter 1: Introduction

- Asked in: 2078 Poush, 2 marks; 2075 Baisakh, 2 marks (asked 2 times)
- Video: [TRANSPORTED SOILS Vs RESIDUAL SOILS](https://www.youtube.com/watch?v=7E6ij26S7-s) — BE A CIVIL ENGINEER 
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/soil_mechanics/residual-transported-soils
- Whole chapter: https://www.bctengineer.com/md/semester_4/soil_mechanics/chapter-1

## Question

Differentiate between residual and transported soils. What would be a solution of different soil engineering problems?

## Short answer

Residual soils remain over parent rock after weathering, are angular and unsorted; transported soils are moved by water, wind, ice or gravity, are rounded and layered. Solutions to soil problems include deep foundations, compaction, drainage, stabilization, and retaining walls.

## Answer

**Residual soils** are formed by weathering of rock and remain at the place of formation. **Transported soils** are weathered particles carried by an agent and deposited away from the parent rock.

| Basis | Residual soil | Transported soil |
|---|---|---|
| Location | At the parent rock | Far from the parent rock |
| Agent | None | Water, wind, ice, gravity |
| Particles | Angular, unsorted | Rounded and sorted by size |
| Depth | Variable, grades into rock below | Often thick and layered |
| Grain size | Wide mixture; fine at top, coarse at bottom | Fairly uniform in each layer |
| Examples | Laterite, black cotton soil | Alluvial, loess, glacial till, colluvium |
| Strength | Depends on weathering depth; weathered rock can be strong | Often loose and compressible |

#### Solutions to soil problems
- **Settlement:** compaction, preloading, drains, or deep foundations.
- **Low strength:** stabilisation, soil replacement, reinforcement with geosynthetics.
- **Slope failure:** drainage, retaining structures, slope flattening.
- **Seepage:** cut-off, filters and sheet piles.
- **Expansive soil:** lime treatment, replacement, and deep foundations.

## Check yourself

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

1. Which statement correctly defines transported soil?
   A. Soil that stays over its parent rock
   B. Soil with no mineral content
   C. Soil formed only by chemical weathering
   D. Weathered particles carried by an agent and deposited away from the parent rock
   Answer: D. Transported soils are carried by water, wind, ice or gravity and deposited elsewhere. (Key point: Definition)

2. Compared with residual soil, transported soil particles are generally:
   A. Angular and unsorted
   B. Rounded and sorted by size, in layers
   C. Always larger than gravel
   D. Identical to the parent rock
   Answer: B. Transport rounds and sorts particles, so transported soils are layered with fairly uniform grain size per layer. (Key point: Particle shape and sorting)

3. Which pair gives examples of residual and transported soils respectively?
   A. Alluvial soil; laterite
   B. Colluvium; black cotton soil
   C. Loess; glacial till
   D. Laterite; alluvial soil
   Answer: D. Laterite and black cotton soil are residual; alluvial, loess, till and colluvium are transported. (Key point: Examples)

4. Which is a listed solution to slope failure?
   A. Cut-off and filters
   B. Drainage, retaining structures and slope flattening
   C. Lime treatment
   D. Preloading with drains
   Answer: B. Slope failure is handled by drainage, retaining structures and flattening; cut-offs are for seepage. (Key point: Solution for slope failure)

## Related in Soil Mechanics

- [Define soil; soil engineering problems](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Adefine-soil-engineering-problems) — Soil Mechanics, chapter 1
- [Factors for residual soil characteristics](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aresidual-soil-characteristics-factors) — Soil Mechanics, chapter 1
- [Geotechnical problems and their solutions](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Ageotechnical-problems-solutions) — Soil Mechanics, chapter 1, asked 2×
- [What is soil mechanics; why study](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Asoil-mechanics-why-study) — Soil Mechanics, chapter 1
- [Field identification of fine-grained soils](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Afield-identification-clay-silt) — Soil Mechanics, chapter 3, asked 4×
- [How soils are formed](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Asoil-formation-process) — Soil Mechanics, chapter 1, asked 2×

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