THE RELATION BETWEEN THE YOREDALE SERIES AND THE MILLSTONE GRIT ON THE ASKRIGG BLOCK

Abstract

Summary The uplift which gave rise to the Bowland Shale overstep at the southern end of the Askrigg Block was late P 2 (pre-E 1 ) in age. This movement had little effect on Yoredalian sedimentation. A later phase of uplift initiated the pre-Millstone Grit unconformity on the Block. The effect of this is very marked in the south, but on the northern margin the break is very slight, if existent at all. The beds above the break are everywhere of approximately the same age, late E 1 , and there is no evidence for a large scale overstep by the Millstone Grit. The basal Millstone Grit sandstone passes laterally northwards into Mirk Fell Ganister of Yoredale facies, but there is no indication of its lateral passage into any of the beds beneath the Mirk Fell Ganister. The Millstone Grit facies encroached farther northwards with time, for the Kettlepot Ganister horizon passes into beds of Yoredale facies in the Stainmore Syncline to the north of the block.