Dob’s Linn

Scotland, United Kingdom

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June 25, 2026

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Dob's Linn, located near Moffat in Scotland, is a significant geological site. It serves as the global stratotype section and point (GSSP), often referred to as the "golden spike," for the boundary between the Ordovician and Silurian periods. This boundary, established in 1985, is marked by the first appearance of the graptolite species Parakidograptus acuminatus. This point also signifies the base of the Llandovery Series, the lowermost division of the Silurian System, which represents rocks deposited between 443.4 and 433.4 million years ago. The environmental conditions at Dob's Linn during the early Silurian were marine waters deep enough to remain unaffected by sea-level changes associated with Late Ordovician glaciation and subsequent deglaciation.12

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Silurian Period
Ordovician-Silurian boundary
…fixed at a horizon in Dob’s Linn near Moff in the Southern Uplands of Scotland. The effect on sea level of Late Ordovician glaciation, combined with increasing deglaciation during the early Silurian, accounts for widespread stratigraphic unconformities at the Ordovician-Silurian boundary that usually omit the P. acuminatus biozone. In earliest…
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…fixed at a horizon in Dob’s Linn near Moff in the Southern Uplands of Scotland. The effect on sea level of Late Ordovician glaciation, combined with increasing deglaciation during the early Silurian, accounts for widespread stratigraphic unconformities at the Ordovician-Silurian boundary that usually omit the P. acuminatus biozone. In earliest…
Read More