Skip to content
Skip to main content


Updated Thursday, 28th September 2006

A brief description of the nature of siltstone

This page was published over 16 years ago. Please be aware that due to the passage of time, the information provided on this page may be out of date or otherwise inaccurate, and any views or opinions expressed may no longer be relevant. Some technical elements such as audio-visual and interactive media may no longer work. For more detail, see how we deal with older content.

Siltstone is a fine to medium-grained sedimentary rock. It is pale grey or brown and quite soft. Sometimes it contains thin layers which are darker or lighter in colour.

Siltstones are made up of particles which are intermediate in size between sandstone and mudstone.


How is it formed?
Siltstones are formed by particles settling through water and accumulating on the ocean floor, river beds or lagoon and lake bottoms. As the silt is buried and compacted by overlying sediment, the water is squeezed out and it turns into siltstone.

Get closer to geology


Become an OU student


Ratings & Comments

Share this free course

Copyright information

Skip Rate and Review

For further information, take a look at our frequently asked questions which may give you the support you need.

Have a question?