Presidential address to the manchester geological association: Sedimentation facies in the namurian of North‐Western England and adjoining areas

Abstract

AbstractThe correlation links which have been established within the Namurian (Plates VIII & IX) across the sedimentation facies of the Central Province and Northern Province are reviewed. It is possible to portray the palaeogeography during particular sub‐zones and to suggest limits for the various facies (Figs. 1–3). A total of seven facies is recognised—sedimentation facies, of fluvial‐grits, of grit‐shales, of coals, of limestones, of Yoredale‐limestones, of Yoredale‐grits and of marine‐shales.In E1a times a marine‐shale facies lay in the Central Province between the Welsh‐Mercian ridge and an E‐W narrow ridge through the Isle of Man to the Settle district; in the Northern Province, northwards from this ridge to the Midland Valley of Scotland, there is a Yoredale‐limestone facies except in the extreme south‐west where lay a limestone facies.In E1c‐d times a fluvial‐grit facies invaded the Central Province from the east, whilst in the Northern Province a Yoredale‐grit facies occupied much area and passed northwards into a coal facies along the Scottish border.In E2b times marine shales passed northwards into a grit‐shale facies in the Central Province whilst a Yoredale‐grit facies predominated in the Northern Province with land areas emerging in the Isle of Man—Lake District, on the Alston Block and along the Southern Uplands.During H times the Northern Province emerged and remained as land until the close of the Namurian. In the Central Province marine‐shales characterized the western part of the basin, the eastern part having a grit‐shale facies, except during upper R1 times when a fluvial‐grit facies spread eastwards almost as far as Preston.