sentences:  Intense evaporation from these lagoons resulted in the precipitation of a carbonate-sulphate complex and the thick halite beds as seen to the south west of Alderley in Northwich where the salt is mined commercially.It was in this type of environment that the Mercia Mudstone Group (formerly Keuper Marl) was deposited.The sequence of formations in the Sherwood and Mercia mudstone groups in this region illustrates clearly the upward transition from continental fluvial to deltaic and littoral marine and ultimately to the hypersaline lake epeiric sea environment of the Mercia Mudstone group.