The stratigraphy and structure of the Cotherstone Syncline

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Abstract
Summary: The Cotherstone area is a physical and geological depression lying between the two upstanding block areas of the northern Pennines. Structurally it is an asymmetrical syncline pitching gently to the east. The succession of Carboniferous rocks displayed ranges from late P 2 to late E 2 and includes beds of Yoredale facies of the Middle and Upper Limestone groups, overlain by Millstone Grit. The tracing of the marine members of the Yoredale rhythmic units or cyclothems has established correlations between the successions of the Alston Block to the north and the Askrigg Block to the south. These show that marine conditions frequently persisted longer to the south and east of the area than elsewhere. Millstone Grit facies enter at a lower horizon on the east and west of the Cotherstone area than they do in the centre, the lower horizon corresponding with the Tan Hill Grits to the south, which, it is suggested, pass laterally into the Coalcleugh Transgression Beds of the north. This is demonstrated by equating the Upper Felltop Limestone of the Alston Block with the Hearne Beck Limestone of Upper Swaledale. The upper horizon, of grit facies, is subjacent to the Botany Limestone and is considered to be the equivalent of the First " Millstone Grit " of Durham and the Water Crag Grit of Upper Swaledale, the Botany Limestone corresponding with the Shunner Fell Limestone.