THE MIRK FELL BEDS (NAMURIAN, E 2 ) OF TAN HILL, YORKSHIRE

Abstract

INTRODUCTION The Mirk Fell Beds outcrop on the high moorlands of North-West Yorkshire in the area drained by the headwaters of the Swale, Eden and Greta. They are mainly shales and occur at the top of the Yoredale Series immediately below the Millstone Grit. They were first discussed by Chubb and Hudson (1925) in a paper dealing with the nature of the junction between the Lower Carboniferous and the Millstone Grit of this region. In that paper the Millstone Grit was shown to be unconformable on various beds in the Yoredale Series in that immediately south of Wensleydale it rests on the Main Limestone but northwards the unconformity lifts and newer beds appear from beneath its base. North of Wensleydale the position of these newer beds in the Yoredale succession of the Northern Pennines is clear: they include the Little Limestone, the Ten Fathom Grit and the Crow Limestone and Cherts. North of Swaledale, however, still newer beds appear beneath the Millstone Grit; they are found in Stonesdale and Arkengarthdale and on the flanks of Rogans Seat and Water Crag moorlands, and are very variable and difficult to place in the Yoredale succession of the Northern Pennines. The lower part consists of a series of shales and cherts with occasional thin limestones; the upper part only occurs beneath the Millstone Grit in the northern part of Stonesdale and Arkengarthdale and around Tan Hill and Mirk Fell. It is these upper beds that are the Mirk Fell Beds. They begin with ...