Shear zones may have long history and cut through large section of the crust. Within one shear zone, deformation structures may vary over time and in space. A cohesive cataclasite with quartz fragments in a cohesive epidote-rich matrix. At very shallow levels the fault rocks can be incohesive . Shortening and stretching is possible during progressive deformation, but also take into account variations over time of applied deformation sheath folds.
Extreme strains can shear out any irregularity in layering into a tubular fold.
Active buckling and rotation enhances formation of sheath folds. They may look similar but are not the same as crenulation cleavages, which normally develop normal to shortening. Develops early in shear zone formation. Mantle is not the same as pressure shadow or pressure fringe With high strain, mantles can get stretched to form wings. Flow field and amount of mantle material determine geometry of mantled porphyroclasts.