{"thcode":4,"term":{"code":"3.2.1","name":"Tuff","parent":"3.2","scope":"Consolidated or cemented volcanic ash."},"uf":[],"bt":[{"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":[{"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."},{"code":"3.2.1.1","name":"Welded tuff","parent":"3.2.1","scope":"A glass-rich pyroclastic rock that has been indurated by the welding together of its glass shards under the combined action of the heat retained by particles, the weight of the overlying material, and hot gasses."}],"rt":[]}