Abstract: A detailed biostratigraphy is established, using the high foraminiferal abundance and diversity at Trowbarrow Quarry, which is also proposed as a stratotype section for the late Asbian (late Viséan), a substage not previously formally subdivided. The foraminiferal assemblages suggest that the early Asbian has to be revised, which has implications for the chronostratigraphy of many late Viséan outcrops in Britain, which are probably erroneously interpreted. From the upper part of the Park Limestone Formation...