In Swaledale, the Stockdale Fault is a major fault that is linked to other major fault systems and marks the northern boundary of the Askrigg Block and southern boundary of the Stainmore Trough. The Stockdale Fault can be seen at Low Bridge and catterby Scar denoted by a limestone escapement along the northern bank of the River Swale upstream of Wain Wath Force. The position of the River Swale has also been partially controlled by the fault as they are natural weakness in the crust, and nature, when eroding the crust, preferentially attacks these broken rocks. Ice and rivers have chosen to use this routeway down the valley as the faulted rocks are least resistant to erosion. The Stockdale fault is a long-lived fault that has been reactivated many times and during latest Carboniferous to earliest Permian times acted as one of the many conduits for hydrothermal fluids depositing the mineral wealth of the dales.
Sketch geological map of the Northern portion of the Yorkshire Dales National Park, including Swaledale.
Map of granite plutons under the Yorkshire Dales, the North Pennines, the Lake District and the Cheviots on the Scottish borders. The Stockdale Fault of Swaledale is an important fault marking the boundary between the upstading Askrigg block and the Stainmore Trough. Adapted from Chadwick et al., 1995.
Cross section north-south from Scottish Borders to the Askrigg Block across Northern England. Note the Stockdale Fault that forms the northern limit of the Askrigg Block and lies along the northern side of Swaledale (after Chadwick et al. 1995. The Northumberland–Solway Basin and adjacent areas. BGS Subsurface Memoir).
Cotterby Scar illustrates the Main Limestone and at the base of the slope next to the far side of the River Swale is the location of the Stockdale Fault orientated parallel with the river and cliff face.
Cotterby Scar
View of Wain Waith Force and Cotterby Scar illustrating the differences in carboniferous stratigraphy across the Stockdale fault. David Medcalf / Wain Wath Force, near Keld / CC BY-SA 2.0