Palynology of the Stonehaven Group, Scotland: evidence for a Mid Silurian age and its geological implications

Palynomorphs from the Stonehaven Group indicate a late Wenlock to early Ludlow age. This is older than the currently accepted Pridoli age based on fish and arthropods. Reasons for this discrepancy are discussed. A previous correlative of the Stonehaven Group has been the Old Red Sandstone of Kerrera, Argyll. However, palynological assemblages from both Kerrera and the adjacent succession at Oban are in fact younger than that from Stonehaven in being of latest Silurian to earliest Devonian age. The palynomorphs from Kerra and Oban lie beneath the important geochronological tie-point of the Lorne Lavas and suggest that the Silurian-Devonian boundary is older than currently accepted.