
Meet) oso > ) PAULTS. ~ 527 
and the Old Red sandstones and conglomerates of the Lowlands of 
Scotland. So powerful have been its effects that the strata on the 
Lowland side have been thrown on end for a distance of two miles 
back from the line of fracture, so as to stand upright along the 
coast-cliffs, like books on a library shelf. Yet at the actual point 
where the fault reaches the sea and is cut in section by the shore- 
cliff, it does not appear as a line of shattered rock. On the 
contrary, no one, placed at once upon the spot, would be likely to 
suspect the existence of a fault at all. The red sandstone and the 
reddened Highland slates have been so compressed and, as it were, 
welded into each other, that some care is required to trace the de- 
marcation between them. 
Variations in the Effects of Faults.—The same fault may give 
rise to very different effects, according to variations in the inclination 
or curvature of the rocks which it traverses, or to the influence of 
branch faults diverging from it. Faults among inclined strata may, 
in most districts, be conveniently grouped into two series, one running 
in the same general direction as the dip of the strata, the other 
approximating to the trend of the strike. They are accordingly 
classified as dip-faults and strike-faults, which, however, are not 
always to be sharply marked off from each other, for the dip-faults 
will often be observed to deviate considerably from the normal 
direction of dip, and the strike-faults from the prevalent strike, so 
that in such cases they pass into each other. 
A dip-fault produces at the surface the effect of a lateral shift of 
the strata. ‘This effect increases in proportion as the angle of di 
lessens, but ceases altogether when the beds are vertical. Fig. 256 

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Fig. 256.—PLAN OF STRATA CUT BY A Drp-F'Avut. 
- may be taken as a plan of a dip-fault (f/f) traversing a series of strata 
which dip northwards at 20°. The beds on the east side look 
as if they had been pushed horizontally southwards. That this 
apparent horizontal displacement is due really to a vertical move- 
ment, and to the subsequent planing down of the surface by denu- 
ding agents, will be clear, if we consider what must be the effect 
of the vertical ascent or descent of the inclined beds on one side of 
a dislocation. ‘The part on one side of the fracture is pushed up, or, 
what is equivalent, that on the other side is let down, If the strike 
