The Bag Tephra is a widespread tephra layer interbedded in Quaternary
loess deposits along the Danubian valley of Hungary and Slovakia. Its
age is poorly defined between 788 and 380 ka B.P. The glass and mineral
composition - micropumice clasts of phono-tephrite and blocky shards of
tephri-phonolite associated with two kinds of clinopyroxene, fassaitic
diopside, and salite - is very distinctive. This tephra could be used
as a chronological marker, as soon as its age is refined. The probable
origin is the middle Italian volcanic area.