Jointing in the Great Scar Limestone of Craven and Its Relation to the Tectonics of the Area

The Great Scar Limestone of Kilnsey Moor, 4 miles northwest of Grassington in Wharfedale, is traversed by many approximately parallel lead-veins whose direction is marked, in the field, by a series of small trial holes for lead. Over the same area, the limestone is cut by two series of joints which are nearly at right angles to each other. One of these sets of joints is parallel to the lead-veins. Traced towards the North Craven Fault, near Skirethorns, both the lead-veins and the joints parallel to them are found to change from a north-east and south-west direction to an east-north-east and west-south-west direction. These observations, which were made in 1926, were sufficient to suggest: (1) that the jointing was probably formed in pre-Permian times, as the joints may be occupied by lead-veins for whose pre-Permian age there is considerable evidence; (2) that the jointing was produced by regional stresses, since it is constant in direction over large areas; (3) that the jointing, since it alters its direction on approaching the North Craven Fault, may be connected in some way with the faulting and may, therefore, throw some light on the nature of the Craven Fault-system. To test these tentative deductions, and, if possible, to decide the relations between the joints and the tectonics of Craven, a detailed map of the direction of the jointing in the horizontally-bedded Great Scar Limestone between Dentdale, Wensleydale, and the Craven Faults was begun. Previous