

162 STRUCTURAL AND FIELD GEOLOGY 
ing retreat of the outcrops in the opposite direction on the 
low side of the dislocation. Similar appearances present 
themselves when a fault cuts across an anticline, as will be 
seen by examining the models in Fig. 39. The anticline 
before dislocation is represented by A, while B shows the 
dislocation completed. When the portion lying above the 
line s s is removed, we have the new surface (C) produced 
by denudation, upon which the outcrops on the high side 
of the fault appear to have been shifted, but in opposite 
directions to the apparent shifting produced on the high 
side of a fault traversing a syncline. In the case of a faulted 
anticline the opposing outcrops on the “upcast” side appear 
to recede from each other, while on the “downcast” side the 
corresponding outcrops seem to have been brought closer. 
together, the appearance of movement in opposite directions 
being, of course, entirely the effect of denudation. 
Strike-faults or, as they are often termed, longdtudinal 
faults, are so called because they trend in the Weemevar 
direction of the strike or the axes of the folds of a district. 
They also affect the outcrops, but in a different way from 
dip-faults. ‘hey do not cause any apparent horizontal shift- 
ing, and therefore are not so easily detected, in many cases at 
least, as ordinary dip-faults. Sometimes their dcwnthrow 
is in the same direction as the inclination of the strata; at 
other times it is in the opposite direction or against the dip. 
In Fig. 40, A represents, as before, a block of strata traversed 
by a strike-fault / 7 the vertical displacement being shown 
in B. In this case the downthrow of the fault is im the 
direction of dip. Removing the higher portion of the model 
above the line s s in B, we have the ground-plan as shown 
in C. Obviously, the effect of a fault hading in the direction 
of dip is to cut out strata—to carry their outcrops below 
the surface. In the area represented by the model A, we 
have a considerable succession of strata numbered consecu- 
tively, I, 2, 3, 4, 5, 6. The same beds are shown in C, but 
some no longer crop out at the surface, but under the surface 
and against the dislocation. The beds 2, 3, and 4 are cut 
out, as it were. 
Let us now take the case of a strike-fault which has a 
downthrow against or in the opposite dtrection to the dip of the 

