For over a century the position of the Silurian-Devonian Boundary has excited controversy and the problem continues to exercise the Committee on the Silurian-Devonian Boundary instituted by the International Commission on Stratigraphy. There has been vigorous activity to examine and adopt a new horizon at which to draw this boundary. Little enough has been said to maintain the value, usefulness and claims of the boundary that has served so long. While we do not wish to stand in the way of an innovation that may, insofar as recognised graptolite zones are used, be better than that which we have used so far, we question whether British geologists have assessed adequately what is involved in the recommendation of the British Silurian Subcommittee. The matter was indeed raised in a letter to the Editor of the Geological Magazine (March–April, 1969, pp. 215–216) by P. T. Warren on behalf of the Institute of Geological Sciences. Warren said ‘. . . we shall, as a matter of policy, in the immediate future at least, continue to use the Ludlovian-Downtonian boundary as the Siluro-Devonian boundary.’ We offer the following points for serious consideration and we stress that it is more important for British geologists to deliberate fully a recommendation before endorsing it, than to give unqualified assent when indeed there are important grounds for hesitation.

Despite the Silurian Committee’s conclusion that the Downtonian stage be included within the Silurian system, there appear to the undersigned to be good reasons for retaining the base

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