The Dinantian stratigraphy of north-west Devon

SUMMARY The Dinantian of north-west Devon is represented by a poorly exposed thin pelagic succession. New sedimentological and palaeontological data permit the recognition of five formations: Pilton Shales (partly Devonian), Landkey, Tawstock (three members), Hearson and Rubble Hills. The last four are newly named and defined, and form part of the Codden Hill (Chert) Group. The two different stratigraphic successions previously proposed are shown to be based on incomplete sequences and erroneous age assessments. Instead, a fairly uniform stratigraphy is recognised. The local variations that do occur can be explained by either tectonic excision of strata (for which there is independent evidence) or basin floor morphology. Redeposited pelagic carbonates suggest a submarine rise existed nearby through much of the Dinantian. Limestone turbidites of shallow-water debris also point to topographic highs in the region.