This website looks at geological structures such as folds, faults, and joints. The definition of geologic structure is any feature produced by the deformation of a rock. A fold is characterized by the bending of a rock.
Faults are fractures along which rock on one side has moved relative to rock on the other side.
A joint is a fracture without movement of rock. Joints and faults often occur as sets of many parallel fractures. Folded Structures A fold is a bend in a rock which tends to show up best in layered rocks, although they do occur in unlayered rocks such as granite. These folds can arch upwards, downwards, or sideways but the effect is always to shorten the crustal rocks. Folds are usually caused by compressional forces.