pyroclastic

adjective

py·​ro·​clas·​tic ˌpī-rō-ˈkla-stik 

: formed by or involving fragmentation as a result of volcanic or igneous action

Examples of pyroclastic in a Sentence

Recent Examples on the Web

But after the eruption buried the trilobites, cool seawater mixed with the hot ash and quickly hardened the pyroclastic flow into a tomb of solid rock. —Mindy Weisberger, CNN, 9 July 2024

Surrounding states, including Montana, Idaho and Wyoming, would face pyroclastic flows—a dangerous high-density mix of hot lava blocks, pumice, ash and volcanic gas. —Thomas G. Moukawsher, Newsweek, 8 Nov. 2024

On May 18, 1980, the eruption of Mount St. Helens emitted 1.5 million metric tons of sulfur dioxide into the atmosphere while its pyroclastic lava flow incinerated virtually everything within a 230-square-mile radius. —Andrew Paul, Popular Science, 7 Nov. 2024

Some hours later, pyroclastic flows—masses of hot gas and ash—hurtled down the mountain, covering the city and killing any survivors. —Byalex Epshtein, science.org, 18 July 2024

Word History

Etymology

probably from pyro- + clastic

Note: The term was introduced by the English geologist Joseph Beete Jukes (1811-69) in The Student's Manual of Geology, new edition (Edinburgh, 1862), p. 68: "The word 'ash' is not a very good one to include all the mechanical accompaniments of a subaerial or subaqueous eruption, since ash seems to be restricted to a fine powder, the residuum of combustion. A word is wanting to express all such accompaniments, no matter what their size or condition may be, when they are accumulated in such mass so as to form beds of 'rock.' We might call them perhaps 'pyroclastic materials'…." In the index pyroclastic is glossed as "broken from fire."

First Known Use

1862, in the meaning defined above