Abstract
The Yamaoku Formation, one of significant Lower Jurassic strata in the inner zone of Southwest Japan, is characterized by alternation of sandstone and shale. Mineral composition and grain size distribution analyses of fifty-one sandstone samples were performed under a microscope. Sandstones were plotted at the central part on QFR diagram and plotted around the QP line on QPK diagram. CM pattern, skewness-sorting diagram and cumulative frequency curves suggest shallow marine environments. These data were stored in a computer file. By using SPSS and several other computer programs, display and statistical analyses of them were processed, such as trend surface analysis, discriptive statistics, discriminant analysis, cluster analysis and factor analysis. These results were discussed from the point of sedimentology, and it is shown that they have many important informations for sedimentological interpretation of the data.
