According to the study of the grain size in the Changjiang Delta

the Luanhe River Delta

the Nanliujiang Delta and Qinzhou Bay

following conclusions are obtained: 1. As far as our information goes

grain size parameters

C-M plots

probability cumulative curves and multivariate analysis can be important in studying depositional environments. 2. Multivariate analysis is a process in which large amount of grain size data are turned into dynamic classification

therefore the hydrodynamic conditions in deposition can be interpreted by it. 3. Probability cumulative curves once had been used to analyse subenvi-ronments. Since they are controlled by various factors

they can not be simply used to distinguish depositional environments. However

in the same depositional system

the curves are regarded as more ideal for distinguishing sedi-mentary environments. 4. The study of grain size distribution can be helpful to the identificationof depositional environments. But it provides simply the information of the general kydrodynamic conditions in the deposition. Only when it is considered together with sedimentary structures

bioturbation and geological settings

canit be good environmental index.