The cross-over point is moved to smaller angles for
trend 2(around 60–701), trend 3(around 30–401), and trend 4
(around 151). For one rock of trend 4(i.e.,Herbeumont Slate),on
average,no cross-over is observed because the fractures in the
weak directions are dominant for all inclination angles. Again,the
synthesis presented in Fig. 10 should not be viewed as a strict
division of categories;rather,it should be viewed as a transition to
the successive trends.