The Silurian strata in south Jiangsu are a series of clastic rocks from the continent which are mainly composed of argillaceous siltstones

silty mudstones with interlayers of lithic quartzareite and mixed with various volcaniclastic components.It has a thickness of more than 1600m.The rock assemblage characteristics and sedimentary structure show that sedimentary environment changed from the shallow marine phase to the coastal phase in Silurian period.Gaojiabian stage was mainly shallow marine phase and was transited to coastal phase.Houjiatang group was typical assemblage of onshore bar lagoon tidal flat coastal phases

where as the Fentou stage was tidal flat environment superposed by the action of storms.Maoshan stage was chiefly foreshore nearshore phases of beach environment.