Article: The Ordovician-Silurian boundary graptolite fauna of Dob's Linn, southern Scotland
S. Henry Williams
The strata at Dob's Linn from the Extraordinarius Band of the Upper Hartfell Shale Formation to 2.3 m above the base of the Birkhill Shale Formation and their contained taxa are described and accurate faunal ranges provided. The boundary separating the Climacograptus? extraordinarius and Glyptograptus persculptus zones occurs within a 1.17 m thick unfossiliferous part of the succession. The boundary between the G. persculptus and Parakidograptus acuminatus zones is defined at 1.6 m above the base of the Birkhill Shale in the Linn Branch section, where Akidograptus ascensus and P. acuminatus s.l. first occur. A member of the Glyptograptus? 'venustus' group is recorded from Britain for the first time. Accurate correlation is attempted with zonal sequences in Soviet central Asia, central China, and eastern Canada.