A second class of kinematic criteria is based of the obliquity between the kinematic and the strain reference framework. Throughout a shear zone the strain axes X and Z rotate to parallel the axes a and b of the kinematic frames. Indeed, the foliation plane or S plane (S for schistosity) rotates and tends to become parallel to the shear plane or C plane (C for the french work cisaillement). As the shearing increases the angle between S and C decreases (sketch A below). This rotation is consistent with the kinematic of the shear zone i.e. a clockwise rotation of the S plane implying a clokwise sense of shear on the C plane.
In the mylonitic zone where C and S are sub-parallel a new generation of shear plane called C' may develop with a small angle (10-15º) to the C plane. This is illustrated in the sketch B on the right, showing a CSC' mylonite.
