CONCERNING THE PROCESS OF THRUST FAULTING 433 



of the member (Fig. 6) , and the tendency to shear due to rotational 

 stress is distributed in parallel planes, one of which must coincide 

 with the plane of maximum shear due to folding. Thus rotational 

 stress adds a tendency to shear along the plane of maximum shear 

 already developed by folding. This explains the low-angle breaks 



Fig. 7. — The rupture of flexed wooden columns by tension and shear. Under 

 flexure, columns tend to split from end to end due to shearing, and to part in a plane 

 at right angles to their long axes above the plane of shear by tension. Tension is 

 greatest at the top of the arch, and shear is greatest along the center of the member. 

 A and B show separate breaks due to shear and tension and C shows rupture induced 

 by a combination of shear and tension. 



near the center of the sHghtly flexed paraffin sheet (Figs. 2 and 5), 

 and the suggestion of a very low-angle break near the center of 

 the ruptured soap (Figs. 2 and 4). 



Contemporaneous with this tendency to shear along a plane 

 parallel to the axis of the deformed member, there is a lesser 

 tendency to rupture by tension. The tensional break approaches 

 a plane normal to the top of the arch, at right angles to the plane 

 of maximum shear (Figs. 6 and jA and B). A combination of 

 these two is a plane which sweeps through a considerable change of 



