volcanic ash  search
RTamorphous materials
 ash falls
 ash flows
 ash-flow tuff
 atmospheric transport
 bentonite
 clastic sediments
 dust
 ejecta
 ignimbrite
 K-bentonite
 nuees ardentes
 pyroclastic flows
 pyroclastics
 sediments
 shirasu
 terrigenous materials
 tuff
 volcanic rocks
 volcanicla
SNIn GeoRef, ash is used for artifical ash. May be used as an igneous rock and a sediment. Also index pyroclastics; OR clastic sediments as applicable (See lists H or N).