Abstract: The cretaceous age geological profile near Tangjiawan in Yichange City has been field sampled and descripted in order to evaluate the grain size sedimentary parameters of sandstone in this age. There are significant changes in the sequence of the cretaceous outcrops although the sequence is generally presented by mud surrounded by sand. The central bar and cross-bedding is common in the sandstone due to the dynamic sedimentary environment. The grain size parameters are consistent in all samples from sedimentary indicators such as, mean grain size, sorting coefficient, skewness and kurtosis. These are the strong and stable indications of the sedimentary hydrodynamic conditions. The overall bouncing in the all grain size groups in the sediment is very developed. The layer in this age is the most representative of the cretaceous braided river facies.

Key words: Wulong Group, Braided River, Grain Size Parameter, Cretaceous Age, Sedimentary Environment