THE BASE OF THE NAMURIAN AND OF THE MILLSTONE GRIT IN NORTH-EASTERN ENGLAND

Abstract

Summary During the last few years evidence has been accumulating which has indicated that the junction between the Lower and Upper Carboniferous, the Viséan–Namurian junction, lies in the vicinity of the Great Limestone at the base of the Upper Limestone Group. The zonal evidence for the position of this boundary is reviewed and five new goniatite records from this part of the succession are described. Two have a direct bearing on the boundary problem— Cravenoceras leion Bisat, the basal goniatite of the Namurian, from the shales above the Great Limestone at Greenleighton quarry, Northumberland, and Cravenoceras aff. malhamense (Bisat) from the shales above the Little Limestone in Swinhope Burn, East Allendale. The base of the Namurian is now shown almost certainly to lie between the Four Fathom Limestone and the Great Limestone; the base of the latter is shown to be the nearest suitable mapping horizon for the base of the Millstone Grit Series.