The stratigraphic sequence in the Susobana-kawa region is as follows: (Quaternary) Terrace deposit Iizuna formation Minochi group (Tertiary)(8) Orihashi formation (7) Nakanogi formation (6) Shimokusukawa formation (5) Arakura formation (4) Machi formation (3) Ju-ni-taira formation (2) Yahagi formation (1) Nishikyo formation The Iizuna formation is principally composed of volcanic detritus., The Tertiary Minochi group represents a great cycle of geosyhclinal deposits which were deposited in the Shigarami basin., The Ju-ni-taira and Machi formations contain many Cyclammina pusilla and other foraminifera, and the Shimokusakawa formation contains Patinopecten healeyi yamasakii, Turritella saishuensis and other mollusca in great abundance., The fossils are a neritic fauna., The principal structural feature of the Susobana-kawa region is the Nishikyo-Kamikusukawa anticline., This anticline is an overturned fold, which becomes an overthrust in the part of the region., And, it is believed that the structure was formed by shearing force which acted in a NW-SE direction.,