pyroclasticadj.n.

1862 J. B. Jukes Student's Man. Geol. (new ed.) iv. 68 The word ‘ash’ is not a very good one to include all the mechanical accompaniments of a subaerial or subaqueous eruption... A word is wanting to express all such accompaniments, no matter what their size and condition may be, when they are accumulated in such mass as to form beds of ‘rock’. We might call them perhaps ‘pyroclastic materials’.

1888 F. Rutley Rock-forming Minerals 124 Breccias and tuffs, whether of pyroclastic origin or not.

1931 Geogr. Rev. 21 269 Visible vents..are wholly absent in the older lavas..and the many favourable natural sections fail to reveal any pyroclastic material or any trace of central vents.

1976 P. Francis Volcanoes v. 158 Pumice is the best-known of all pyroclastic..rocks.

2000 Jrnl. Biogeogr. 27 1051/2 Coastal erosion has been dramatic,..as the unconsolidated pyroclastic deposits forming the majority of the coastline provided little resistance to wave action.

1896 C. D. Walcott Cambrian Rocks Pennsylvania ii. 20 An acid volcanic rock..is amygdaloidal or compact, is accompanied by pyroclastics and breccias, and [etc.].

1939 W. H. Twenhofel Princ. Sedimentation viii. 291 The coarse-grained pyroclastics fall near the places of expulsion.

1976 P. Francis Volcanoes iv. 127 All volcanic rocks..may turn up either as lavas or pyroclastics.

2000 Science 19 May 1200/1 Eastern flows..could be from an earlier stage of the 1997 eruption but covered with thick insulating pyroclastics from the plume that accompanied the eruption.

1938 M. G. Wilmarth Lexicon Geol. Names U.S. ii. 1650 Phoenix volcanic group.—Pyroclastic flows (?) and contemp. intrusions of porphyrite.

1941 H. Williams in Geology, 1888–1938 (Geol. Soc. Amer.) 379 Between such continuous lava flows as the pahoehoe and the ultra-pulverized tuff flows just mentioned, magma may pour out in all degrees of comminution. This recognition of truly pyroclastic flows is among the chief discoveries of the last few years.

1961 T. Nagata & S. Akimoto in T. Nagata Rock Magn. (rev. ed.) xi. 318 Mud flow deposits..are formed at atmospheric temperatures, while..pyroclastic flow deposits, and some tuff, tuff-breccia, pumice and scoria fall deposits are known to be deposited at the temperatures very close to that of magma.

1997 N.Y. Times 17 Feb. 44 Martinique's Mt. Pelée,..erupting back in 1902, had killed nearly thirty thousand people when a pyroclastic flow incinerated the town of St. Pierre.

2006 Philippine Daily Inquirer (Nexis) 5 Oct. There was still continuing threat from sudden explosions..and secondary pyroclastic flows as a result of the collapse of the newly deposited lava at the upper and middle slopes.