Ignimbrite
A consolidated deposit of a pyroclastic density current, particularly an ash-flow deposit, welded or unwelded.
Language and route: Scientific Latin ignis + imber. Scientific Latin ignis + imber
Literal gloss: fire-shower
The name and its history
Patrick Marshall (1932), followed by detailed 1935 monograph · 1932 coinage documented by Te Ara; 1935 original paper online
- What does the word literally mean?
- The immediate route is Scientific Latin ignis + imber. In its naming context it meant ‘fire-shower’; deeper associations must be distinguished from the geological term's original purpose. The date of the 1932 naming act and date of the major 1935 descriptive paper are distinct; “shower” should not imply simple fallout.
- What did the original author mean?
- Patrick Marshall proposed ignimbrite in 1932 for widespread fragmental volcanic deposits in New Zealand, elaborated in his 1935 Taupō–Rotorua study.
- Why was the name needed?
- The origin of enormous rhyolitic sheets was debated between lava-flow and fragmental-emplacement interpretations.
- What evidence supported the original concept?
- Ash, pumice fragments, sheet geometry, welding, compaction and petrographic textures in New Zealand.
- How has geology changed the concept?
- Modern interpretation treats ignimbrites as pyroclastic density-current deposits, and recognises welded and unwelded varieties.
Further historical context
Patrick Marshall proposed ignimbrite in 1932 for widespread fragmental volcanic deposits in New Zealand, elaborated in his 1935 Taupō–Rotorua study.
The origin of enormous rhyolitic sheets was debated between lava-flow and fragmental-emplacement interpretations.
Ash, pumice fragments, sheet geometry, welding, compaction and petrographic textures in New Zealand.
Modern interpretation treats ignimbrites as pyroclastic density-current deposits, and recognises welded and unwelded varieties.
Editorial qualification
The date of the 1932 naming act and date of the major 1935 descriptive paper are distinct; “shower” should not imply simple fallout.
Related names
Tuff · Rhyolite · Pumice · Pyroclastic
Sources
- Te Ara, Rocks named in New Zealand — Marshall 1932 coinage, original hot-ash cloud explanation
- P. Marshall (1935), Acid Rocks of the Taupo–Rotorua Volcanic District — Primary elaboration of field evidence, temperatures, texture and emplacement
- Te Ara, Patrick Marshall — Biographical account of volcanic study
- British Geological Survey, Rock Classification Scheme — Authority for modern rock categories and distinctions