C/N ratios and sulfur and pyrite content in coals from separate basins show a good correlation with inferred paleoenvironments. C/N ratios indicate the extent of input by land plants, and the pyrite content implies sea water incursion into the basins. An analysis of C/N ratios and pyrite content in carbonaceous materials can rapidly be used to classify sedimentary environments in coal basins.

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Large earthquake is a trigger of submarine slope failures, and may form submarine gravity flow deposits such as turbidites and subaqueous debris flow deposits. Therefore, there is a possibility that the recurrence intervals of submarine gravity flow deposits intercalated in hemipelagic mud indicates those of large earthquakes occurred near a site. The recurrence intervals of deep-sea turbidites deposited in the Kumano Trough, a forearc basin along the Nankai Trough, where large and destructive earthquakes occurred periodically, were determined to evaluate the deep-sea sediments as earthquake recorder. Radiocarbon datings using planktonic foraminifers in hemipelagic mud were carried out at 10 horizons. By using the foraminifer ¹⁴C ages, depositional age of each turbidite layer could be determined in high accuracy. The reccurrence intervals of turbidites were calculated as 170-680 years. This intervals were 2 or 5 times longer than the recurrence interval of large earthquakes along the Nankai Trough. The largest problem of the age determination is thought to be the reserver effect of radiocarbon in ocean.

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The turbidite of the Kamikozawa Formation in the Tomikura region was deposited in a NE-SSW trending trough-basin at the west flank of the Tomikura Anticline and in a channel-like trough basin at the east flank differentiated by tectonic movement from latest Miocene to Pliocene time. In the eastern channel-like trough basin, andesite clasts were supplied laterally from the Kato Mountains, south of the Tomikura area, by tectonic uplift of asement rocks, and channel-fill deposits were developed. In the trough-like basin at the west flank, turbidite deposits were formed by sheet flow turbidity currents supplied longitudinally from the Minochi region southwest of the Tomikura region. The Tomikura region was a junction of a NNE-SSW trending trough continuous from the Minochi region to the Higashikubiki region and a channel-like trough connected from the Kato Mountains to the south.

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Curvature profiling software used in this study adopts cubic parametric spline function. Three types of ripples such as wave ripples and two kinds of combined-flow ripples with adverse currents and favorable currents, respectively, were formed in a recirculating flume with a wave generator. These bed forms were investigated.
Wave ripples are characterized by symmetric profiles, while current ripples by asymmetric profiles. Some combined-flow ripples are symmetric profiles other are asymmetric. Both of symmetric and asymmetric combined-flow ripples have rounded profiles. Ripple Index (RI) and Ripple Symmetry Index (RSI) have been known for the distinction of morphology of ripples. But there is no good index for representing the roundness. In this paper, distribution profiles of curvature are calculated to distinguish the combined-flow ripples from wave ripples. Results from investigating morphological feature of combined-flow ripples are presented as examples.
The results of analyses were that it is possible to distinguish differences of these ripples by calculating distribution profiles of curvature. Consequently it turned out for the first time that stoss sides of combined-flow ripples with favorable currents became longer than lee sides as relative magnitude of unidirectional velocity to oscillatory velocity became higher, while combined-flow ripples with adverse currents kept symmetric profiles of ripples.

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This article gives an overview of recent lacustrine studies from a paleoenvironmental point of view, focusing on organic and inorganic geochemical studies to lacustrine deposits. Conclusions of selected studies are; 1. carbon isotopic composition of organic matters reflects climatic changes, 2. carbon isotopic composition of land-plants (C3, C4) is controlled by paleoclimate around lakes, 3. C/N ratio of organic matters reflects origin of the organic matters, 4. oxygen isotopic composition of primary carbonates is a measure of salinity and water balance of lake, and 5. integrated studies to combine microfossil analysis and geochemical analysis improve the reliability of conclusions. Lacustrine studies are expected to provide valuable information in reconstructing paleo-environments in relation with human societies and activities and predicting near future environmental change of the Earth's surface.

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