Definition of clast in English:

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Pronunciation: /klast/


A constituent fragment of a clastic rock.
Example sentences
  • The clasts in volcaniclastic rocks may range from fine ash to bombs and enormous blocks.
  • This is substantiated by the presence of eroded Permian carbonate clasts.
  • The siltstones contain poorly sorted angular fragments of quartz, and angular clasts and cleavage fragments of plagioclase and alkali feldspar.


Mid 20th century: back-formation from clastic.

For editors and proofreaders

Line breaks: clast

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