Lower Pleistocene Invasion and Pleistocene Terraces on the Japanese Pacific Coast

Abstract

In this paper the Pleistocene terraces and the Lower Pleistocene marine invasion of the Japanese Pacific coast are considered, The writer has divided the Japanese Quaternary deposits into the. following subdivisions: _??_ Of these subdivisions, “dl II” contains Elephas namadieus naumanni MAKIYAMA andd many fossil, marine, shells on the Pacific coast., Between “dl”. beds or below the “Elephas namadicus naumanni M AKIYAMA” horizone, an extensive unconformity has been observed by Japanese writers. The distribution of marine “dl II” beds on the Pacific coast is shown in Fig. a. The “du” beds above “dl II” generally consist of gravel and coarse sand beds. The writer, therefore, concludes that in the early Pleistocene, the Pacific Ocean. invaded. these parts of the Japanese coast. The regions that were covered by the inva _??_ion have been preserved as very smooth flat surfaces, forming coastal terraces I and other flat topographies..Prev ously, the writer divided the Japanese topographic plain into the followir.g subdivisions: A, Du, Dl, Pd Plain. The writer's “Du”, plain agrees with these coastal. terraces and other flat topographies just mentioned. The “Du” plain may therefore be the depositional plain of “dl II, ” which underwent some modifications during the “du” stage. But since no “dl II” are developed on the “Dl” plain, the “Dl” plain may antedate the “dl II” invasion.