BGS Rock Classification Scheme
Agglomerate - A type of pyroclastic-rock. In the Rock Classification Scheme, it is a pyroclastic-rock in which more than 75% of the pyroclastic fragments exceed 64 mm in size. Agglomerate and pyroclastic-breccia are separated according to the relative proportion of blocks (angular fragments exceeding 64 mm) and bombs (rounded fragments exceeding 64 mm): if bombs dominate over blocks the rock is agglomerate. It is the consolidated equivalent of bomb-tephra or block-bomb-tephra. British Geological Survey Research Report RR/99/06, section 4.2 and fig. 4.
| Code | AGG |
|---|---|
| Description | Agglomerate - A type of pyroclastic-rock. In the Rock Classification Scheme, it is a pyroclastic-rock in which more than 75% of the pyroclastic fragments exceed 64 mm in size. Agglomerate and pyroclastic-breccia are separated according to the relative proportion of blocks (angular fragments exceeding 64 mm) and bombs (rounded fragments exceeding 64 mm): if bombs dominate over blocks the rock is agglomerate. It is the consolidated equivalent of bomb-tephra or block-bomb-tephra. British Geological Survey Research Report RR/99/06, section 4.2 and fig. 4. |
| Qualifiers | No qualifiers currently exist. |
| Definition | Unimodal well sorted lithified clastic material (>10% debris) formed by volcanic processes; >75% pyroclastic fragments, >75% >64mm bombs (rounded) >blocks, <25% 2-64mm lapilli + <2mm ash |
| Linked data | http://data.bgs.ac.uk/id/EarthMaterialClass/RockName/AGG |
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.