In ideal shear zones without volume change, the extension fractures make an angle of 45 and cleavage of 135 degrees with the direction of shear. In case of volume increase, the angle that extension fractures make is always less than 45 degrees and cleavage makes an angle with the shear direction that is less than 135 degrees. If there is volume loss during shearing, the extension fractures make an angle >45 degrees since the maximum stress becomes more compressive and the related fabric makes an angle with the shear direction which is greater than 135 degrees. In case of no volume loss but no shear the banded perturbations of P type develop. If there is volume loss, the perturbation is generally marked by development of cleavage, generaly stylolitic during brittle-ductile regime or schistose fabric during ductile regime. In case of volume increase only extension fractures may develop in brittle ductile regime or boudinage and related structures in ductile regime. The figure is reproduced from Ramsay (1983) -Ed Hsu K J Mountain building Processes.