Gassan volcano is an extinct (?) Quaternary stratovolcano.
Gassan volcano can be classified into earlier and later stages.
During the earlier stage, dacitic lavas were erupted from
the western side of Gassan volcano and formed the
Amamoriyama and Yudonosan edifices. During the later
stage, andesitic lavas were erupted out and formed Gassan
and
Ubagatake edifices. A horseshoe shaped caldera caused by
the collapse of the central part of Gassan volcano can be
observed. (after Iai and Ban, 2003).
Gassan is seen on the 24 yen value of the sheet below
issued on October 18th, 1952
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