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Tuff identification and geology

A rock composed of consolidated volcanic ash and other fine pyroclastic material <2 mm diameter ejected during explosive volcanic eruptions. Tuffs are classified by their composition rhyolitic, dacitic, andesitic, basaltic and the nature of their fragments: crystal tuff abundant crystal fragments , lithic tuff rock fragments , and vitric tuff glass shards . Welded tuffs ignimbrites are formed from hot pyroclastic flows whose fragments fuse together upon deposition. Field: volcanology. Example: The Bandelier Tuff of New Mexico is a welded ignimbrite erupted from the Valles Caldera approximately 1.6 and 1.2 million years ago, forming the dramatic cliff dwellings at Bandelier National Monument.. Related terms: Pyroclastic, Ignimbrite, Ash, Welded tuff.

Sources, scope & corrections

These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.

Editorial owner
GeoMiner
Last updated
2026-03-30T15:19:42.096023+00:00
Review status
Published; not independently peer-reviewed
  • USGS Thesaurus — U.S. Geological Survey. Controlled earth-science terminology used to describe USGS information resources.
  • Glossary of Geologic Terms — U.S. National Park Service. Geologic definitions prepared by the NPS Geologic Resources Inventory.

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Common questions

What does Tuff mean in geology?
A rock composed of consolidated volcanic ash and other fine pyroclastic material <2 mm diameter ejected during explosive volcanic eruptions. Tuffs are classified by their composition rhyolitic, dacitic, andesitic, basaltic and the nature of their fragments: crystal tuff abundant crystal fragments , lithic tuff rock fragments , and vitric tuff glass shards . Welded tuffs ignimbrites are formed from hot pyroclastic flows whose fragments fuse together upon deposition.
What is an example of Tuff?
The Bandelier Tuff of New Mexico is a welded ignimbrite erupted from the Valles Caldera approximately 1.6 and 1.2 million years ago, forming the dramatic cliff dwellings at Bandelier National Monument.
Which earth-science field uses the term Tuff?
Tuff is used in volcanology.
Which terms are related to Tuff?
Related terms in this reference are Pyroclastic, Ignimbrite, Ash, Welded tuff.

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