In order to clarify sedimentary environments of the latest Pleistocene to Holocene in the Akkeshi area, diatom analyses of bottom surface sediments on Akkeshi Bay and Lake Akkeshi, and diatom analyses and electrical conductivity measurements of the Akkeshi core, 59.22 m long, drilled from the sea floor 2.9 m deep of Akkeshi Bay were carried out. Cocconeis scutellum, Fragilaria faciculata and Thalassionema nitzschioides abundantly yield from the surface sediments. On the basis of diatom compositions, the Akkeshi core can be divided into four diatom zones in ascending order, Aulacoseira ambigua - Navicula contenta - Navicula mutica zone, Cocconeis placentula var. euglypta - Cocconeis scutellum zone, Thalassionema nitzschioides - Thalassiosira eccentrica - Thalassiosira hyalina zone and Cocconeis scutellum - Paralia sulcata - Thalassiosira hyalina zone. Results of diatom analyses show the seawater inundation during the Holocene transgression occurred at the depth of -47.6 m in the Akkeshi core, and its geologic time is inferred as ca 11.2 cal. ka. Salinity indices calculated from diatom compositions suggest that the present lake water salinity is nearly equivalent to the basal part of unit Es, -39.9〜-36.95 m deep of the core.

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The 'Sueki' ancient pottery sites and the ruins of their kilns constitute the Minamihiki ruin group of kilns, the largest archaeological site of the "Big Four Ruins of Kilns in Musashi Province" in west Kanto Plain, that is densely scattered throughout the Iwadono Hills, Saitama Prefecture, Japan. The clay for 'Sueki' has been known to be derived from marine sedimentary rocks of this hill based on occurrence of fired marine siliceous sponge spicules from 'Sueki'. Fragments of 'Sueki' collected from the Shogunzawa 1A ruin of kilns in Ranzan Town and the Kawasaki site in Fujimino City yield the middle Miocene radiolarians. This age is the same with the depositional age of the Shogunzawa Mudstone Member of the Iwadono Formation. While fragments of 'Sueki' collected from the Osugi site in Ogawa Town and clay from Sue in Hatoyama Town contain the late Miocene radiolarians. This indicative age of radiolarians shows the same to that of the Hatoyama Sandstone and Mudstone Member of the Ohashi Formation. As the small fragments of 'Sueki' and a small amount of the clay for 'Sueki' examined in this study certainly yield radiolarians, both are considered to be derived from radiolaria-rich sedimentary rocks of the Shogunzawa Mudstone and Hatoyama Sandstone and Mudstone members.

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Well-preserved many specimens of the trace fossil Zoophycos were found in the Upper Miocene-Lower Pliocene Aoshima Formation of the Miyazaki Group distributed along the Nichinan Coast in southeastern Kyushu, Japan. All of Zoophycos occur in very fine-grained sandstone beds and are of the helical-coil type. The characteristic recurved structure was observed in the lowest spreite of some Zoophycos, although all spreite of many Zoophycos spread obliquely in the downward direction to the bedding plane. The present Zoophycos with recurved spreite is the first record. The depth of the recurved lowest spreite in the sandstone beds shows that the spreading of the lowest spreite is strongly influenced by a change in the grain size; the lowest spreite was recurved upward in the bottom of the very fine grained sandstone beds overlaying on the parallel laminated fine grained sandstone beds.

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