62 PEARL SHELDON 
and one N. 80° W. These were the best seen for measurements, 
since one face of the faults had usually fallen away and the direction 
of movement could be read directly from the strong, even striations 
on the slickensided surfaces. Many other faults in this layer were 
seen but were inaccessible for measurement. The inclination of 
these faults is sometimes south and sometimes north and the angles 
are nearly the same in the two cases, making the faults symmetri- 
cal about a nearly horizontal plane. In the readings made the hade 
varied from 45° to 75°, but most were near the average, which was 
62°. These faults usually continue for a few feet in the adjacent 
shale, but instead of continuing with the same hade they flatten 
out and become nearly horizontal as in the shales where no hard 
layer is present. 
Since the faults of this region are usually nearly horizontal it 
might be expected that where well-developed bedding planes are 
present the slipping would take place along these. This is not 
true in the case of the encrinal layer. The unusually steep angle 
of the faults there seems to be due to the hardness of the rock, 
which has more influence on the location of the slipping planes 
than the presence of planes of weakness along the stratification. 
Some of the best of the horizontal faults were in nearly homogene- 
ous shales, not along bedding planes. Evidently the bedding 
planes do not control the angle of the faults. 
It is probable that the strike of the faults in the shales is about 
the same as that of the small faults in the hard layer which could 
be measured. It is noticeable that the strike varies from the 
direction of the axis of the fold by a rather large angle and that 
this angle increases eastward with the rise of the pitching fold. The 
faults were probably formed at the same time as the folds, that is, 
during the Appalachian Revolution, since no other disturbance of 
sufficient strength to produce these uniform faults is known here. 
The faults show that the direction of the local resultant force 
varied considerably from the general direction of the active force 
which produced the folds if the axes of the folds are at right angles 
to the latter. The explanation seems to lie in the pitch of the 
folds. Localities 9, 14, and 39 are in an anticline which rises 
rapidly to the east. The direction of movement points in toward 
