The coal-forming models in late permian eporch in Guangxi are divided into "two classes and three types", the two classes are peat bog coal-forming model and peat flat coal-forming model, the three types are bog type, tidal flat type and peat flat type coal-forming models.

After a brief review of the previous studies on distributions and physical environments of Chinese open-coast tidal flats,this paper focuses on analyses of the continuity of tidal flat deposits based on our long time field observations.

Shell sediments on tidal flat near Dongying Harbor of Yellow River Delta;

On the basis of tidal bedding,herringbone cross-bedding,flush cross bedding and plenty of shells,it has been identified that the sedimentary environment of the study area is of tidal flat environment.

The Silurian in this area is tide-controlled coastline sedimentary environment and here mainly developed the tidal flat depositional system.