大阪層群のイ***ー火山灰層準における海成相とケイソウ群集(近畿地方の新期新生代層の研究-18-)

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In previous papers, it is already recognized that the eight transgressions took place at the Osaka Basin in early Pleistocene Age and that the remarkable continuous clay beds, given the following symbols; Ma 1, ……Ma 8, in ascending order, were deposited in internal bays (ITIHARA: 1960). Recently, TAKETSUJI and ITIHARA (1967) and NAKAGAWA (1967) discovered a marine-like clay bed about 20m. under Ma 1, at the Senriyama Hills and the western part of Nara City.The writers carried out the analysis of the diatom flora in order to know the environment in which the marine-like clay bed were deposited. We obtained the following results;Osaka Group{Ma 1 marine Ryugaike volcanic ash lacustrine? marine……Coscinodiscus cf. commutatus, Cos. rothii var. normanii, Cyclotella striata etc. Yellow volcanic ash lacustrine……Gommphonema augur, Stephanodiscus niagarae etc. Grey volcanic ash marine……Coscinodiscus cf. commutatus, Cos. rothii var. normanii, Cyclotella striata, Cyc. stylorum etc marine……Coscinodiscus rothii var. normanii, Cycltella striata etc.