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Texture of sedimentary rocks and 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.

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

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.

✓ Answer checked by Claude Opus 5.5 (high effort)

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