Joints are very common and at same time very complex structures in rocks.

In folded regions, joint orientation is conveniently described with reference to hinge of fold. Joints running parallel to hinge line are called radial joints.

Repeated expansion and contraction is characteristic of regions with dry hot (arid) climates where day and night temperatures on one hand and summer and winter temperatures on or hand vary within a very wide range of -50° to 60° C.

Joints have dip and strike, dip being ir inclination with horizontal and strike being direction of intersection of a joint plane with a horizontal plane.

Mural jointing is a sort of geometrical distribution of joints dividing rock mass into cubical blocks or murals and hence name.

Sheet joints are sometimes caused due to wearing and removal of overlying rock masses, which cause expansion of underlying igneous and or rocks as a consequence of unloading.

Systematic joints occur in parallel or sub-parallel joint sets that are represented in rocks at regular intervals. The columnar joints and mural joints are examples of regular or systematic jointing.

Treating negative qualities of rocks due to joints will differ in different projects. The first requirement in all cases is, however, detailed investigations to establish full characteristics of joints.

Shear joints are commonly observed in vicinity of fault planes and shear zone where relationship with shearing forces is clearly established. In folded rocks, se are located in axial regions.

Under classification based on geometry, three types are recognized: Strike joints, dip joints, oblique joints.