Abstract
A peculiar formation was recently reported from Kamimasuki-gun, Kumamoto-ken, central Kyusyu by certain geologists working on Southwest Japan., And the present paper is a report of our preliminary study on it., The complex is here called provisionally the Mizukosi formation., It is a thick series of slaty shale with intercalating members of conglomerate and sandstone and containing lenses of limestone., It is noteworthy that the conglomerate contains iu abundance rounded pebbles, cobbles, and boulders of granite and altered green andesites or porphyrites ; and the material of sandstone is also grains derived mainly from similar igneous rocks., Through the study of fossils (see list in the Japanese text) found in the limestone, we have ascertained that the formation belongs to the upper Titibu system, i., e., the Permian., In conclusion, we have pointed out several geological problems related to the Mizukosi formation., Among them the question of Palaeozoic igneous aetivity in the Japanese Islands may be the most interesting.,
