{"thcode":4,"term":{"code":"3.2.1.2","name":"Ash-flow tuff","parent":"3.2.1","scope":"A tuff deposited by an ash flow or gaseous cloud; a type of ignimbrite.  It is a consolidated, but not necessarily welded deposit."},"uf":[],"bt":[{"code":"3.2.1","name":"Tuff","parent":"3.2","scope":"Consolidated or cemented volcanic ash."},{"code":"3.2","name":"Pyroclastic rock","parent":"3","scope":"...clastic rock material formed by volcanic explosion or aerial expulsion from a volcanic vent."},{"code":"3","name":"Volcanic rock","parent":"0","scope":"A generally finely crystalline or glassy igneous rock resulting from volcanic action at or near the Earth's surface, either ejected explosively or extruded as a lava.  The term includes near-surface intrusions that form a part of the volcanic structure."},{"code":"0","name":"Earth material","parent":null,"scope":"Geologic map unit classification (Bruce R. Johnson) version 6.2: A hierarchical classification of earth materials for digital geologic maps."}],"nt":[],"rt":[]}