A lineation is any linear feature or element in a rock, and can occur as the product of tectonic, mineralogical, sedimentary, or geomorphic processes. Lineations are the one-dimensional counterparts of foliations, and both are part of the fabric (geometric organization of features) of a rock. Lineations and foliations are said to possess preferred orientations, meaning that the spatial orientation of the features comprising the lineation or foliation is similar throughout the rock mass.

The spatial orientation of a lineation is described by two angles known as bearing and plunge. The plunge angle is the inclination of the lineation relative to an imaginary horizontal plane (ranging from 0 to 90 degrees), whereas the bearing angle is the compass direction of the lineation in the direction of the plunge (ranging from 0 to 360 degrees).

Structural lineations are those that are formed by tectonic activity such as folding, faulting, or metamorphism. Structural lineations can...