Grain size distributions of coarse sediments from a shallow depth of an accretionary prism were examined by two-dimensional image analysis using thin sections. The analyzed samples were obtained during Integrated Ocean Drilling Program (IODP) Expedition 311. Statistical parameters such as kurtosis, skewness, and correlation coefficients of exponential and power functions show no relationship with depth and porosity. There is an inverse relationship between the correlation coefficients of exponential and power functions, indicating that some grain size distributions can be classified. The correlations also relate to sediment textures. Samples with rounded and isolated grains have a higher correlation coefficient with the exponential function. Angular grains and a denser packing texture represent a lower correlation coefficient with the exponential function.