A REVISED CHRONOSTRATIGRAPHY FOR THE LOWER DURNESS GROUP

The significant breaks proposed by previous researchers in the Cambro- Ordovician succession of north-western Scotland to explain the absence of Mid- and Late Cambrian faunas cannot be justified by field evidenc e. Moreover, comparison with the once contiguous succession of western Newfoundland suggests that the Scottish succession contains both Midd le and Upper Cambrian strata. Age-diagnostic faunas from the Early Cam brian Bonnia-Olenellus Zone in both sequences allow the upper Forteau Formation and the lower Hawke Bay Formation of western Newfoundland to be biostratigraphically correlated with the lithologically similar Fu coid Beds and Salterella Grit, and with the basal dolostones of the Gh rudaidh Formation, in north-western Scotland. Similarly, Early Canadia n cephalopods and matching lithostratigraphy allow the correlation of the Scottish Lower Ordovician Sailmhor Formation with the Watts Eight Formation in western Newfoundland. These benchmarks, together with the close similarities of lithostratigraphy, facies, faunal trends and pa tterns of cyclicity, allow the Eilean Dubh Formation of north-western Scotland to be correlated with the dolostones of the Upper Cambrian Pe tit Jardin and Berry Head formations of the interior shelf of western Newfoundland. The middle and upper Ghrudaidh Formation can also be cor related with the Middle Cambrian Bridge Cove Member of the upper part of the Hawke Bay Formation and the overlying Upper Middle Cambrian Mar ch Point Formation, suggesting that the Cambrian succession in north-w estern Scotland is largely continuous.