FAULTS. 183 
of this fracture should drop down many hundreds of feet. Now, to go from 
the low lands to the high lands it would be necessary to climb a great wall. 
We must- conceive this line to be a somewhat meandering one, so that 
the wall is turned more or less from a direct course. Again, the throw of 
the beds is variable, being greater or lesser here and there along the fault 
in some places, but two or three hundred feet, perhaps; in others, two or 
three thousand. For this reason the altitude of the cliffs is greatly variable. 
Again, the brink, or edge, of the irregular wall has tumbled down in 
many places, leaving pinnacles, towers, and crags here and there, and below 
may be seen a great talus, where the rocks which have tumbled down are 
piled against the foot of the wall. Then there are streams heading in the 
upper country, and running down into the lower, which have cut for them 
selves channels narrow gulches, or, perhaps, in some places, narrow valleys, 
so that we have, not a vast, unbroken wall, but an irregular line of cliffs. 
Let us turn our attention to these faults, and the topographic features 
to which they give rise. Sometimes we find that the beds are broken by a 
well defined fracture, and the plane of separation between the beds which 
have dropped down and those which have remained in place is clearly 
marked. Figure 64 is designed to represent a section across such a fault, 
where the bed , a on the left is seen to lie at a higher level than on the 
right. Sometimes the fault branches, and the throw, or displacement, occurs 
along two or more lines, so that a great step may be broken into two or 
more smaller ones, as represented in Figure 69, where the bed , a is 
seen in each step. In other places, the beds have fallen down without 
obstruction for a part of the distance, and have been caught and turned up, 
as in Figure 71. In many places we find no definite line of separation 
between the strata in place and the fallen strata, and there is a space of 
greater or lesser extent, sometimes several hundred feet wide, between the 
two -series, composed of fragments of the same rocks, in some cases, thrown 
down promiscuously, and found much mixed, as seen in Figure 65; but in 
others, preserving, in an irregular, broken way, the stratification, by a flex 
ure, from the upper to the lower beds, as seen in Figure 66, where the rocks 
seem to have been torn asunder by the stretching they received in displace 
ment. Again, we find the rocks intervening between the horizontal beds 
