HORIZONTAL MOVEMENT IN OBLIQUE FAULTING 
OF INCLINED STRATA 
CHARLES KEYES 
In the White Basin of southern Nevada, where extensive borax 
deposits were discovered a few years ago, the depression is formed 
by a huge drop-fault block, in which the displacement is more 
than 1000 feet and there appears a curious set of oblique faults 
which meet the major side-fault at an angle of 45 degrees. The 
strata being inclined about 30 degrees renders the direction of 
movement conspicuous. This is horizontal. 
These oblique faults do not seem to form straight lines but 
are slightly convergent. At first glance they appear to be ex- 
pressions of relief from tortional stresses. But the tract under 
consideration is a part of the Muddy Mountains lately deter- 
mined to be not a typical exemplification of Basin Range structure 
but a huge thrust-block. Mountain thrusts are commonly regarded 
as low-angled faults, the plane of rupture being nearly horizontal. 
On a ground plat the faults under notice are disposed obliquely 
to the main fault bounding White Basin, which is seven miles 
removed from the line where the thrust reaches sky, in the 
steep face of the Muddy Mountains. While the movement of the 
minor faults is horizontal the plane of motion is vertical and at 
right angles to the strike of the thrust. It seems probable, there- 
fore, that these minor faults are not to be attuned to the White 
Basin fault, but are in reality expressions of movement not here- 
tofore recognized. If they are actually a necessary and ordinary 
result of thrusting the fact is important in fixing the date of the 
thrusting, for they cut the boraciferous beds which are doubtless 
Miocene in age. 
