"Conjugate shear fold systems are often developed when brittle laminated rocks are subjected to stress. These structures may have an orthorhombic, monoclinic or triclinic symmetry depending upon the relationship of the principal axes of stress to the surface being folded. Within first order shear zones conjugate second order shear folds may be developed as a result of reorientation of the stress axes in these zones. The axes of both first and second order conjugate shear folds may form at any angle to the principal stress axes and to the direction of movement within the shear zones. The principal axes of stress are most reliably determined from the orientation of the axial planes of the first order conjugate folds."