Ingleborough - Geology

Geology

The striking appearance of Ingleborough from all directions and from a great distance is due to the unusual geology of the underlying rock. The base of the mountain is composed of ancient Silurian and Ordovician rocks and it is on these that the village of Ingleton stands. A belt of Carboniferous Limestone, the 'Great Scar Limestone', some 600 feet (180 m) thick, lies on top of this. Due to the limestone's permeability, all the streams flowing down from the mountain are engulfed upon reaching it, falling into a number of potholes. Above lies the layered Yoredale Series of sedimentary rocks, predominantly shale and sandstone, and generally concealed by the peat but revealed in the escarpments about 1,700 feet (520 m) up. There are also layers of harder limestone sandwiched between the softer rocks which have been eroded faster, and which protect the layers beneath them, leading to the 'tiered' effect. The whole mountain, however, is protected from erosion by a cap of Millstone Grit, known as the Yoredale Series, approximately 100 feet (30 m) tall. The rock above the Millstone Grit layer has been eroded away, which explains the flatness of the summit. A good explanation of the geology and scenery of the area is given in Waltham.