In the introduction, the writer emphasizes strict discrimination of differences between observable stratigraphic units and inferential ones, between stratigraphic paleontology and paleontological stratigraphy, and relationship between geologic time units (defined first) and time-stratigraphic units (defined secondarily). He also points out that biostratigraphy (in sense of stratigraphical paleontology) depends primarily upon two independent factors, namely, lithostratigraphy and identification of fossils, and thus, biostratigraphy done by excellent taxonomists (systematic paleontologists) is not always good and sometimes confusing or misleading, unless geologic horizons of examined rock samples are correctly determined by cooperation of good geologists. He concludes that the greatest defect of modern biostratigraphy lies in determinations of geologic horizons of examined rock samples rather than accuracy of identifications of fossil species. For these reasons, the writter shows locations of examined rock samples clearly based on large scale topographic maps or his own field mapping (Figs. 1-4), and also shows geologic horizons of them based on kind cooperation of many geologists of Geological Survey of Japan, oil companies and universities (Figs. 4-5). The surface rock samples were collected by the writer in many areas including type exposures of the standard formations of the Niigata oilfields, and cuttings of two boreholes were used at an interval of 20m with one exception of 10m interval. These samples were analyzed semiquantitatively. Based upon the detailed results from Sado Island already reported (Uchio, 1971-1974), results from the other areas of the Niigata oilfields are interpreted, and the Hazime Stage and upper part of the Nishiyama Stage (though these stage names are not appropriate in view of recent stratigraphical nomenclature) are found to belong to the Braarudosphaera bigelowi-Coccolithus pelagicus Zone, an assemblage zone as emended previously (Uchio, 1974c).
In order to start a comparative study of Japanese Palaeogene and Cretaceous sedimentasy basins, the dry sandstone samples from Muroto Peninsula, Izumi, and Kuma groups in Shikoku were studied with high pressure experimentation up to 1500 bars. All studied rocks are coarse or medium grained well sorted sandstones and collected from 6 localities which are different each other in geological horizons. Porosity ranges between 2.2 and 5.7%. The stressstrain curves as the result of the experimentation are shown in Figs 2 to 7. In these figures, strong dependance of porosity for both strength and deformational behavior was obviously indicated. The relation of strength versus porosity is shown nearly linear in semi-log diagram at each confining pressure as indicated in Fig. 9, although the sampling localities are scattered in three different sedimentary basins. Comparision with Kishima-Sassebo groups in northwestern Kyushu was shown in Fig. 8.In this Kishima-Sasebo basins, thick sedimenttary cover of approximately 3500m have been deposited, and, it is indicated, that as it is getting deep, porosity and deformational behavior changes regularly from the brittle deformation of less porous samples seated at lower stratigraphic horizon (HSF or HSG) to the more ductile deformation of more porous samples at upper horizon (HSD or HSC). Such a good accordance with Kishima-Sasebo groups in porosity-deformation relation indicates that the strength-porosity relation in Shikoku sandstones is closely related with compaction mechanism.