40 R. T. CHAMBERLIN AND W. Z. MILLER 
place at an angle as high as 45° upward from the resultant of the 
forces, would still be only 26° 34’ from the horizontal. The 
relative magnitude of the horizontal thrusting force and the 
weight of the heaped-up mass determines how much the angle of 
faulting, under the given conditions, will be diminished from 45°. 
If the weight of the load gave a force equal to half that of the lat- 
eral thrust, the angle would be lowered because of this factor to 
the extent of 26° 34’, thus making it 18° 26’ from the horizontal. If 
the vertical force due to the extra load amounted to one-fourth the 
horizontal thrust, the angle of faulting would be lowered approxi- 
mately 14° 2’, leaving it 30° 58’ from the horizontal. The resulting — 
angle for the various stress ratios may readily be calculated. 
i> 
Lu, 
39404 WOILYSA 
HORIZONTAL THRUST 
Fic. 18.—Diagram to illustrate the position of a fault plane inclined 45° to the 
resultant of forces. The horizontal thrust is here taken to be three times the vertical 
force. Result: the fault plane will be inclined 26° 34’ from the horizontal. 
The effect of adding load, and hence additional force acting 
downward, is to subject the material under thrust to increased 
cubical compression. According to the principles so strikingly 
worked out by Adams and his colleagues, the effect of this should 
be to increase the internal resistance of the material and thus 
necessitate a much greater stress difference to initiate deformation 
than would be required without the additional load. Greater 
stress difference necessitates much greater lateral thrusts. As a 
result faulting may be hindered or even prevented altogether 
until much greater thrusts are developed. It may also, in conse- 
quence, be caused to take place elsewhere, as, for example, some 
distance beyond the edge of the loaded area. In our experiments 
with weighting the faulting most frequently appeared at the surface 
close to the border of the weighted portion, the fault plane dipping 
