Pyroclastic 3 : Pertaining to fragmented (clastic) rock material formed by a volcanic explosion or ejection from a volcanic vent. (Foxworthy and Hill, 1982)
U.S. Department of the Interior, U.S. Geological Survey, US Geological Society (USGS), Glossary of Volcano and Related Terminology, USGS/Cascades Volcano Observatory, Vancouver, Washington, USA 2006. http://vulcan.wr.usgs.gov/Glossary/volcano_termino logy.html, (ND/ Volc Sci - Amer) {493}