Abstract
Lithologic characters and radiolarian fossil evidence suggest that the Miyoshino district is occupied by Cretaceous strata belonging to the Shimanto Belt, except for the B Formation (Chichibu Belt) which is distributed in the uppermost part of tectonic piles as a nappe. The formations (tentatively nominated) in this district and their ages are as follows. Akataki Formation; Turonian〜 Takahara Formation; Jurassic-Cretaceous Makio Formation; Coniacian-Santonian〜 Miyoshino Formation; Late Albian-Cenomanian〜 Heibara Formation; Jurassic-Cretaceous The strata of the Shimanto Belt are widely distributed in the central area of the Kii Mountains including the study district. It is possible that the Shimanto Belt is in fault contact with the Sambagawa Belt, lacking the Chichibu Belt.
