BGS Rock Classification Scheme

Ash-breccia - A type of pyroclastic-sediment. In the Rock Classification Scheme, it is a pyroclastic-sediment which contains more than 25% of each of the main pyroclastic fragment size divisions: blocks and bombs (>64 mm), lapilli (2 - 64 mm), and ash (<2 mm). It is the unconsolidated equivalent of tuff-breccia. British Geological Survey Research Report RR/99/06, section 4.2 and fig. 4.

Code ASHBRC
Description Ash-breccia - A type of pyroclastic-sediment. In the Rock Classification Scheme, it is a pyroclastic-sediment which contains more than 25% of each of the main pyroclastic fragment size divisions: blocks and bombs (>64 mm), lapilli (2 - 64 mm), and ash (<2 mm). It is the unconsolidated equivalent of tuff-breccia. British Geological Survey Research Report RR/99/06, section 4.2 and fig. 4.
Qualifiers No qualifiers currently exist.
Definition Unlithified clastic material >10% debris formed by volcanic processes, >75% pyroclastic fragments, >25% of each of blocks/bombs >64mm, lapilli 2-64mm & ash <2mm, fragments dominantly angular
Linked data http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/ASHBRC

CAVEAT

"Thumbnail" definitions attached to some of the table entries are an interim attempt to provide simple short descriptions of the "unqualified" rock types presented within the BGS Rock Classification Scheme. Every effort has been made to ensure accuracy and consistency but minor contradictions or omissions might be present. The BGS welcomes any feedback pointing out such minor imperfections and/or providing constructive comment and suggestions for improvement of the definitions. In the first instance such feedback should be directed to Dr Tim McCormick.