tuff


tuff
tuff1
/tuf/, adj. Slang.
tough (def. 13).
tuff2
tuffaceous /tu fay"sheuhs/, adj.
/tuf/, n. Geol.
a fragmental rock consisting of the smaller kinds of volcanic detritus, as ash or cinder, usually more or less stratified. Also called volcanic tuff.
[1560-70; < F tuf < It tufo. See TUFA]

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Relatively soft, porous rock that is usually formed by the compaction and cementation of volcanic ash or dust.

Tuff may vary greatly not only in texture but also in chemical and mineralogical composition. In some eruptions, foaming magma wells to the surface as an emulsion of hot gases and incandescent particles; the shredded pumice-like material spreads swiftly, even over gentle slopes, as a glowing avalanche (nuée ardente) that may move many miles at speeds of 100 mph (160 kph).

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      a relatively soft, porous rock that is usually formed by the compaction and cementation of volcanic ash or dust. (The Italian term tufa is sometimes restricted to the soft, porous, sedimentary rock formed by the chemical deposition of calcite, or calcium carbonate, or silica from water as sinter.) Tuffs may be grouped as vitric, crystal, or lithic when they are composed principally of glass, crystal chips, or the debris of pre-existing rocks, respectively. Some of the world's largest deposits of vitric tuff are produced by eruptions through a large number of narrow fissures rather than from volcanic cones.

      In extensive deposits, tuff may vary greatly not only in texture but also in chemical and mineralogical composition. There has probably been no geological period entirely free from volcanic eruptions; tuffs therefore range in age from Precambrian to Recent. Most of the older ones have lost all original textures and are thoroughly recrystallized; many old basaltic tuffs are represented by green chlorite and hornblende schists and many rhyolitic tuffs by sericite schists.

      In some eruptions, foaming magma wells to the surface as an emulsion of hot gases and incandescent particles; the shredded pumaceous material spreads swiftly, even over gentle gradients, as a glowing avalanche (nuée ardente) that may move many kilometres at speeds greater than 160 km (100 miles) per hour. After coming to rest, the ejecta (erupted matter) may be firmly compacted by adhesion of the hot glass fragments to form streaky, welded tuffs (welded tuff) (ignimbrites) such as those covering vast areas in New Zealand, Guatemala, Peru, and Yellowstone National Park in the United States. When explosions occur underground, the fragmental material may be forced violently into the surrounding rocks, forming intrusive tuffs (peperites (peperite)).

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Universalium. 2010.

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  • Tuff — (from the Italian tufo ) is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff should not be confused with tufa , another type of rock. Volcanic ashThe products of a volcanic eruption are… …   Wikipedia

  • Tuff — Tụff 〈m. 1〉 Sediment aus vulkanischen Auswürfen; Sy Duckstein, Tuffstein [<ahd. tuf , tubstein, südital. tufo <lat. tophus, tofus, vermutl. <osk.] * * * Tụff [gleichbed. ital. tufo (lat. tofus)], der; s, e: 1) vulkanischer Tuff: ein… …   Universal-Lexikon

  • Tuff — (Tuffstein) Sm per. Wortschatz fach. (10. Jh.), mhd. tuftstein, tupfstein, ahd. tufstein, tubstein, tuhstein Entlehnung. Mit verdeutlichender Komposition entlehnt aus it. tufo, zu l. tōfus. Die einfache Form beruht auf erneutem Anschluß an das… …   Etymologisches Wörterbuch der deutschen sprache

  • Tuff — Tuff, n. (Min.) Same as {Tufa}. [1913 Webster] …   The Collaborative International Dictionary of English

  • tuff — tuff; tuff·a·ceous; …   English syllables

  • Tuff — Tuff, 1) Trümmergesteine, bei welchen in einem seinen, aus zerriebenen od. zerstäubten Gesteinen entstandenen Bindemittel Bruchstücke verschiedener Gesteine od. Krystalle verschiedener Mineralien eingeschlossen[922] sind; immer herrscht das… …   Pierer's Universal-Lexikon

  • Tuff — Tuff, lockerer Absatz aus Wasser (wie Kalktuff, Kieseltuff, Kreidetuff), ferner ursprünglich in Form von Asche, Sand oder Lapilli ausgestoßenes und unter dem Einfluß des Windes oder des Wassers mehr oder weniger geschichtetes, zuweilen auch… …   Meyers Großes Konversations-Lexikon

  • Tuff — Tuff, zelliges, mürbes, zerreibliches Gestein, durch Mitwirkung des Wassers gebildet; entweder vulkanischer T., d.h. mehr oder weniger fest verbundene Anhäufungen vulkanischer Ausschleuderungsprodukte (Basalt , Bimsstein T.) oder Kalk T. (s.d.) …   Kleines Konversations-Lexikon

  • tuff — fonosimb. CO 1. voce che imita il rumore di un tuffo o di qcs. che cade nell acqua; anche s.m.inv. Sinonimi: tuffete. 2. spec. iter., voce che imita il rumore di una locomotiva a vapore; anche s.m.inv. Sinonimi: tuffete. {{line}} {{/line}} DATA:… …   Dizionario italiano

  • tuff — advertiser s spelling of TOUGH (Cf. tough) (adj.), attested by 1940 …   Etymology dictionary

  • tuff — ► NOUN ▪ a light, porous rock formed by consolidation of volcanic ash. ORIGIN Latin tofus …   English terms dictionary


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