Mytilus-type and cylinder-type bioclasts in a shell bed of the Tsukinoura Formation, Oshika Group, were interpreted for paleocurrent analysis. The bioclasts, composed mainly of Retceramus cf. galoi, belemnites and plant fragments, are scattered on the shell bed; therefore they may sufficiently reflect the paleocurrent that formed the shell bed. Orientation of the beaks of R. cf. galoi and a solemarking in the shell bed suggest a current toward east-northeast. R. cf. galoi on the shell bed imbricate toward both northwest and southeast. In addition, the orientation of the longitudinal axis of belemnites, plant fragments and R. cf. galoi on the shell bed indicates waves having a southwest-northeast axis. The beaks of R. cf. galoi have the deviation of southeast direction. Thus the shell bed may have recorded both bidirectional and unidirectional paleocurrents. According to this interpretation, the shell bed would have been formed either by 1) a current toward east-northeast first, then waves having a southwestnortheast axis, or by 2) a combined-flow of a current toward east-northeast and waves having a southwest-northeast axis. If the southwest-northeast axis of the waves indicates the shoreline direction, the current toward east-northeast should have been parallel to the shoreline. This current may be a geostrofic current.

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Both heavy mineral analysis and modal composition analysis were carried out for the same sandstones in the Late Cretaceous Terasoma Formation of the Shimanto Supergroup in the Kii Peninsula, Southwest Japan. Heavy mineral assemblages of the lower part of the Terasoma Formation are rich in zircon and garnet associated with epidote, titanite and allanite. In the upper part, Zircon is also abundant, but only minor amounts of garnet and anatase are contained. The modal composition of the sandstones from the lower Terasoma Formation are situated in the boundary zone between feldspathic and lithic wacke, and rich in K-feldper and granitic rock fragments. The sandstones from upper formation are more dominant in rock fragments, and belong to lithic wacke without exception. The provenances deduced from the heavy mineral composition are in accordance with the those from the modal composition; the provenance of the sandstones in the lower Terasoma Formation was composed chiefly of granitic rocks, whereas in the upper part of the formation felsic volcanic rocks became predominant. Similar transition of sandstone composition in the middle Late Cretaceous is also recognized in the Soto-Izumi Group, which is situated in the north and correlated with the Terasoma Formation in age. Judging from the modal and chemical composition of sandstones from the Cretaceous Shimanto Supergroup in Japan, violent felsic magmatism took place in the provenance areas where granitic rocks were mainly exposed associated with minor andesitic vol-canism.

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A computational study on the development of sand dune morphology was performed to extend mathematical models that modulate depositional processes of creep, saltation and avalanche. Basically the numeric expressions are based on the equations of sand-transport budget and diffusion. To figure cross-sectional asymmetry, an equation for saltation with apparent contrast of the quantity and distance of blown sand on stoss side, summit and lee side, and an equation for avalanche on lee side are necessary. The results of the simulation of dunes agree with real dune fields on the points of plan form and the cross sectional topography. In spite of simplifying the physical processes of dunes dramatically, this simulation indicates that parameters such as sand quantity, saltation distance and current directions are the fundamentals for dune development. Although any set of formulae describing whole behavior of the dune system has not yet been established, this simulation should be one of the methods to better understand the phenomenon.

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