The sequence of Silurian graptolite zones in the British Isles

Abstract Much modern work on graptolite sequences in the British Isles has provided considerably greater detail regarding species occurrence and range than was available to Elles and Wood (1901‐18) and requires that the more refined zonal schemes of, for example, Rickards (1967, 1969, 1970) and Toghill (1968a) should be more fully discussed than was possible in Strachan (1971), Cocks et al. (1971), or Ziegler et al. (1974). The zonal scheme favoured by the writer is discussed zone by zone, and reference is made to the various difficulties which may obtain, to other zonal schemes in use, and to the questions of local, national and international usage. A summary range chart of British Silurian graptoloids is included as Table I.