NEOGENE TUFFACEOUS LAYERS CONTAINING THE PALAEOGENE SANDSTONE PEBBLES IN THE VICINITY OF OKUSA, NORTH OF NAGASAKI CITY

Along the coast of Okusa, the tuffaceous layers consisting of tuffs and tuff breccias are well exposed are compared with the Kikitsu plant beds including the Mogi fossil flora, being overlain or intruded by the two pyroxene andesite lavas of Nagasaki volcano. It is noted that these tuff breccias include considerably subangular pebbles and cobbles of the Palaeogene sandstone presubably derived from the Palaeogene exposed around Hidake. Besides these, a angular pebble of hyperthene-biotite-hornblende rock was obtained from the tuff breccia of Oura. In this paper the writer mainly described the field observations of these tuff breccias. Similar tuffaceous layers are found also in the basal part of Tara and Uki volcanos. The writer is investigating in the geologic relations between these volcanos through their palaeontological and stratigraphical studies