pyroclastn.
/ˈpʌɪrə(ʊ)klɑːst/, /ˈpʌɪrə(ʊ)klast/, U.S. /ˈpaɪroʊˌklæst/ Geology.
A pyroclastic rock fragment; (also) a pyroclastic rock. Cf. pyroclastic n.
ΘΚΠ
the world > the earth > structure of the earth > constituent materials > rock > igneous rock > [noun] > volcanic rocks > volcaniclastic > fragment
pyroclast1920
1920 A. Holmes Nomencl. Petrol. 193 Pyroclasts, a general term for fragmental deposits of volcanic ejectamenta.
1934 Bull. Amer. Assoc. Petroleum Geologists 18 1573 The bentonite beds in the basal McLure shale represent purer beds of originally vitric pyroclasts.
1944 A. Holmes Princ. Physical Geol. xx. 443 The great clouds of gases, vapours, and pyroclasts that are the most conspicuous feature of explosive eruptions may be luminous or dark.
1962 H. F. Von Bandat Aerogeology xxi. 246 Layers of fine and coarse pyroclasts, occasionally with some lava, are conformable with the outer slope of the cone.
2000 A. Milne Doomsday vi. 63 Incandescent pyroclast flows, tens, even hundreds, of feet thick, poured out over much of the North Island of New Zealand, vaporizing all living matter in the process.
This entry has been updated (OED Third Edition, December 2007; most recently modified version published online March 2022).
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