THE MID-VISEAN (S 2 —D 1 ) SUCCESSION IN NORTH DERBYSHIRE AND NORTH-WEST ENGLAND

Abstract

In 1908 Sibly described the Carboniferous Limestone succession in North Derbyshire and North Staffordshire, applying a zonal scheme which was correlated with the type-sequence of the Avonian (12). The North Derbyshire succession was said to be an expanded development of the Dibunophyllum Zone, at least in so far as the exposed beds are concerned, for the base of the formation nowhere reaches the surface. In 1922 Jackson, following a study of the associated fauna, suggested that the lowest beds of the Carboniferous Limestone exposed in the Wye Valley section (type section for the massif-facies in North Derbyshire) should be referred to the upper part of the Seminula Zone (11, p. 467). It was later indicated that the lowermost 300 ft. of this section is of S2 age (3, p. 143). Reasons have previously been given for placing the boundary between the D1 and D2 subzones about 25 ft. below the upper lava flow (toadstone) in the Miller’s Dale area (6). This paper deals with the exposed part of the S2 subzone and the whole of the D1 subzone. Certain details of the lithology and palaeontology have been given previously (3). Further data more recently obtained are however incorporated in order to make a direct comparison with the corresponding portion of the Lower Carboniferous succession in the North-West of England (Westmorland and Yorkshire), as described in detail by Garwood (7 and 8). THE S2—D1 SUCCESSION IN NORTH DERBYSHIRE. The lithological succession and the more important details of the palaeontology of …