The selection of the base of the Monograptus uniformis zone as the new Silurian-Devonian boundary as proposed by C. H. Holland (for reference, see this Bibliography Vol. 31, No. 3, 18 E67-02281; see also No. 9, 18 E67-08162) is examined. It is felt that there is no need to establish a new boundary until a datum horizon is found that meets more widespread international agreement and that a boundary based essentially on graptolite species is not of wide enough applicability.

GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States