Abstract
The stratigraphy of the Cenozoic formations in Okuyamada, near Kyoto, Japan, has not been previously studied in detail, even though the locality has long been known to amateur fossil collectors as a unique source of marine molluscan fossils., The stratigraphy of the Tsuzuki group is as follows : Ofuku gravel (Pleistocene ?) ., ., ., unconformity ., ., ., Tsuzuki group Yuantani formation Tawara arkose sandstone and conglomerate Shiodani sandstone Okuyamada formation Kaya tuffaceous mudstone Miyamura sandstone bed Kawakami conglomerate ., ., ., unconformity and fault ., ., ., Chichibu Paleozoic formations The Yuantani and Okuyamada formations each represent a cycle of sedimentation., The geologic age of the Tsuzuki group is probably middle Miocene (F2-F3) because of the occurrence of Katelysia nakamurai, Protorotella yuantaniensis and Comptoniphyllum Naumanni, and also of species common to the Ayugawa and Mizunami groups.,
