Mudstone

These are some of the oldest rocks in the Dingle Peninsula, being Silurian in date. They consist of mudstones and siltstones with some volcanic material (County Kerry)

A mudstone is a siliciclastic sedimentary rock which has a mixture of silt- and clay-sized particles (at least 1/3 of each). So, a mudstone is a type of mudrock with a more varied grain size than either siltstones or claystones.

Alternatively, some sources say it is a synonym for mudrock.

Claystone in Slovakia

Claystone

A claystone is a mudrock which does not split easily.

In order for a rock to be a claystone, it must be up to half (50%) clay, whose particles measure less than 1/256th of a millimeter.

References

  1. ↑ Blatt H; Middleton G & Murray R. 1980. Origin of sedimentary rocks. 2nd ed, Prentice Hall, Englewood Cliffs, N.J. ISBN 0-13-642702-2
  2. ↑ Kearey P. The new Penguin dictionary of geology. London: Penguin Books. p176