Rocks become deformed when the Earth’s crust is compressed or stretched. The forces needed to do this act over millions of years – deformation, bending and breaking of rocks is a very slow process! The rocks of Swaledale have been affected by many events over geological time and provide the geologist with many geological structures to understand these events. These geological structures include joints, fractures, folds and faults, all of which significantly influence an area’s rocks and landscape. Swaledale contains structures of many different types and ages, ranging from tiny fractures to major faults which have influenced the entire landscape.
A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other. This movement may occur rapidly, in the form of an earthquake – or may occur slowly, in the form of creep. Faults may range in length from a few millimetres to thousands of kilometres. Most faults produce repeated displacements over geological time as represented here for the Carboniferous rocks of Swaledale. Image ©Elizabeth Pickett, 2022.
