Middle-upper devonian palaeogeography of North Devon and west Somerset, England
Abstract Most of the thick, argillaceous and arenaceous deposits of the Ilfracombe Beds and Morte Slates are considered to have accumulated in shallow-water prodelta and delta-platform environments during Givetian and Frasnian times. The thin, predominantly biostromal limestones in the Ilfracombe Beds also seem to have formed in comparatively shallow-water conditions; three separate coral assemblages in the limestones possibly reflect slightly different depositional depths. A series of palaeogeographical maps for the upper part of the Hangman Grits and the Ilfracombe Beds is presented, in order to illustrate the sequence of depositional events throughout the Givetian of North Devon and West Somerset, and a general synthesis of Givetian palaeogeography in southwestern England and South Wales is also given.