---
title: "Conglomerate versus agglomerate"
subject: "Engineering Geology I"
chapter: 4
key: "semester_3/engineering_geology_i:conglomerate-versus-agglomerate"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/conglomerate-versus-agglomerate
site: BCT Engineering
---

# Conglomerate versus agglomerate

Engineering Geology I · Chapter 4: Petrology

- Asked in: 2075 Asoj, 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/conglomerate-versus-agglomerate
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-4

## Question

Differentiate between conglomerate and agglomerate.

## Short answer

Conglomerate is a sedimentary rock with rounded gravel clasts cemented in a sand/silt/calcite matrix, bedded. Agglomerate is a pyroclastic igneous rock with angular volcanic fragments in ash, chaotic and unbedded.

## Answer

| Point | Conglomerate | Agglomerate |
|---|---|---|
| Rock class | Sedimentary (clastic) | Igneous (pyroclastic) |
| Origin | Rounded gravel transported by water and then cemented | Volcanic bombs and blocks ejected from a volcano and consolidated |
| Fragments | Rounded to sub-rounded pebbles | Angular to sub-angular volcanic fragments |
| Matrix/cement | Sand, silt, clay; silica, calcite or iron oxide | Volcanic ash and tuff |
| Structure | Bedded | Unbedded, chaotic |

## Check yourself

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

1. Conglomerate and agglomerate respectively belong to which classes?
   A. Igneous and sedimentary
   B. Both sedimentary
   C. Sedimentary and igneous (pyroclastic)
   D. Both metamorphic
   Answer: C. Agglomerate is volcanic fragments. (Key point: Rock class)

2. Which has angular fragments?
   A. Conglomerate
   B. Both equally
   C. Neither
   D. Agglomerate
   Answer: D. Volcanic fragments are not transported and rounded. (Key point: Fragment shape)

3. Which is bedded?
   A. Conglomerate
   B. Agglomerate
   C. Both
   D. Neither
   Answer: A. Agglomerate is unbedded and chaotic. (Key point: Structure)

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