---
title: "Texture of sedimentary rocks and rock cleavage"
subject: "Engineering Geology I"
chapter: 4
key: "semester_3/engineering_geology_i:texture-of-sedimentary-rocks-and"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/texture-of-sedimentary-rocks-and
site: BCT Engineering
---

# Texture of sedimentary rocks and rock cleavage

Engineering Geology I · Chapter 4: Petrology

- Asked in: 2074 Asoj, 3 marks
- Video: [Mineral Identification...Cleavage vs. Fracture](https://www.youtube.com/watch?v=1SGC3VBQZY0) — Marc Bieler
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/texture-of-sedimentary-rocks-and
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-4

## Question

Define and describe the texture of sedimentary rocks. Describe rock cleavage.

## Short answer

Sedimentary rock texture is clastic (grain size, shape, sorting) or non-clastic (crystalline, oolitic). Rock cleavage is the tendency of fine-grained metamorphic rocks like slate to split along parallel planes from directed pressure, affecting slope stability and providing roofing material.

## Answer

#### Texture of sedimentary rocks
**Texture** is the size, shape and arrangement of the grains making up a rock. In sedimentary rocks:
- **Clastic texture**: made of fragments of older rocks cemented together. Grain size ranges from gravel (>2 mm) through sand (2 to 1/16 mm) to silt and clay (<1/16 mm). Grains may be angular or rounded, and well or poorly sorted. Examples: conglomerate, sandstone, shale.
- **Non-clastic texture**: crystalline (rock salt, gypsum), oolitic (limestone with small spherical grains), bioclastic (shell fragments) or amorphous (chert).

#### Rock cleavage
**Rock cleavage** is the tendency of a rock, usually a fine-grained metamorphic rock such as slate, to split along parallel planes produced by directed pressure, independent of the original bedding. It is a secondary structure. Examples are slaty cleavage and fracture cleavage. It makes rocks weak along (parallel to) the cleavage and affects slope and tunnel stability, but it also gives roofing slate.

## Check yourself

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

1. Clastic texture is
   A. interlocking crystals from precipitation
   B. gas holes
   C. foliated minerals
   D. fragments of older rocks cemented together
   Answer: D. Examples: conglomerate, sandstone, shale. (Key point: Clastic texture)

2. Rock cleavage is developed by
   A. directed pressure, independent of original bedding
   B. sedimentary deposition
   C. cooling of magma
   D. dissolving by acid
   Answer: A. It is a secondary structure in fine-grained metamorphic rocks like slate. (Key point: Rock cleavage)

3. A rock with cleavage is
   A. strongest across the cleavage
   B. weak across the cleavage but gives roofing slate
   C. unaffected for slopes
   D. ideal for aggregate
   Answer: B. Cleavage affects stability. (Key point: Cleavage effect)

## Related in Engineering Geology I

- [Texture of sedimentary rocks](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atexture-of-sedimentary-rocks) — Engineering Geology I, chapter 4, asked 2×
- [Texture of igneous rocks](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atexture-of-igneous-rocks) — Engineering Geology I, chapter 4, asked 4×
- [Metamorphism and rock cleavage significance](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Ametamorphism-and-rock-cleavage-significance) — Engineering Geology I, chapter 4
- [Rock types, rock cycle, sedimentary rock properties](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Arock-types-rock-cycle-sedimentary) — Engineering Geology I, chapter 4
- [Classification of sedimentary rocks](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aclassification-of-sedimentary-rocks) — Engineering Geology I, chapter 4, asked 4×
- [Identify sedimentary rocks in the field](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aidentify-sedimentary-rocks-in-the) — Engineering Geology I, chapter 4