Cataclasite
Cohesive fault rock dominated by brittle mechanical fragmentation of the original grains.
Language and route: English formation from Greek κατά (katá, down) and κλάσις (klásis, breaking), mediated through scientific cataclasis. English formation from Greek κατά (katá, down) and κλάσις (klásis, breaking), mediated through scientific cataclasis
Literal gloss: crushed / broken rock
The name and its history
Historical fault-rock nomenclature; first individual coiner unverified · established twentieth-century geological usage
- What does the word literally mean?
- Immediate linguistic pathway: English formation from Greek κατά (katá, down) and κλάσις (klásis, breaking), mediated through scientific cataclasis. Relevant original form: κατά + κλάσις (katá + klásis); conventional gloss ‘crushed / broken rock’. The linguistic gloss should not be mistaken for the original scientist’s stated motive unless directly demonstrated.
- What did the original author mean?
- Petrologists needed to distinguish rocks broken by brittle faulting from those recrystallised and foliated in ductile shear zones.
- Why was the name needed?
- As explanations of deformation improved, the presence of broken grains became a classification criterion rather than a single genetic theory.
- What evidence supported the original concept?
- Angular fragments, crack networks, comminuted matrix and relations to fault surfaces.
- How has geology changed the concept?
- Cataclasite is differentiated from mylonite by dominant deformation mechanism; some shear zones record mixed brittle and ductile histories.
Further historical context
Petrologists needed to distinguish rocks broken by brittle faulting from those recrystallised and foliated in ductile shear zones.
As explanations of deformation improved, the presence of broken grains became a classification criterion rather than a single genetic theory.
Angular fragments, crack networks, comminuted matrix and relations to fault surfaces.
Cataclasite is differentiated from mylonite by dominant deformation mechanism; some shear zones record mixed brittle and ductile histories.
Editorial qualification
Etymology of Greek components is straightforward; historical first coiner/date not demonstrated.
Related names
Sources
- USGS glossary and bibliography of cataclastic rocks — Historical terminology for cataclasite, phyllonite and mylonite; full page not independently inspected
- BGS Northern Highlands: mylonite definition and field evidence — Distinguishes original mill analogy from predominantly ductile recrystallisation
- BGS Loch Eriboll field guide — origin of thrust and mylonite — Historic sequence; Geikie thrust 1884, Lapworth mylonite 1885