The sequence of sediments between 2 Upper Carboniferous (Westphalian A) coals in the Lancashire Coalfield is described with particular reference to Ravenhead Quarry, near Wigan. Part of this succession consists of regularly-bedded laminated sandstone/siltstone units containing nonmarine bivalves and their escape shafts. The escape shafts provide evidence of rapid sedimentation. At least 4 sandstone/siltstone units accumulated within the lifetime of a bivalve community which eventually died out because of failure of recruitment of new spat. Sedimentation was controlled by monsoons. The sandstone accumulated during wet seasons, intervening siltstones during dry seasons.