The soil mixed with paper is taken from a stratum called the second tuff of the Miocene Kobe group at the foot of a mountain, from a terrace in Najio, which is exposed here and there.
紙に漉き入れする泥土は、名塩の山麓や段丘に神戸層群第二凝灰岩と呼ぶ地層があり、所々に露出している。