Yew Cogar Scar, Arncliffe, Littondale Nearly all the major cave systems of north-west Yorkshire and the adjacent counties are formed in the thick limestones, known as the Great Scar Limestone. This is the lowest part of the Carboniferous (Mississipian) succession in the area. Black Keld resurgence is formed in the Great Scar Limestone. However the Black Keld system is unusual, because many of the caves draining to the resurgence enter the Yoredale Series of Limestones first. The Yoredale Series is a repetitive cyclic series of limestones, shales and sandstones. The shales and sandstones form a barrier to downward drainage of water. Mossdale and Langcliffe caves both have long sections of crawling passages in which the floor is composed of sandstone. This is actually channeling water away from Black Keld. In Langcliffe a layer of sandstone and shale is penetrated at the Boireau Falls and Nemesis boulder chokes and the passages beyond are much larger. However the cave still hasn't been followed into the Great Scar Limestone. Predictions have been made as to what will happen when the caves reach the Great Scar Limestone. These have varied from, "it will be small and phreatic" (Dave Elliot 1976), to more optimistic descriptions of large passages and pitches (drops) stepping down. Who will be right?! |
