
602 GEOTECTONIC (STRUCTURAL) GEOLOGY. [Boox IV. 
that more than one unconformability may be detected in the same 
section. Thus in Fig. 314, the break between the quartzite (q) 
and Old Red Sandstone (s) is to the eye much more violent and 
complete than that between the sandstone and the overlying gravels 









































































































































































































































































Fia. 314.—DousLn UNCONFORMABILITY AT CULLEN, BANFFSHIRE. 
q, Quartzite ; s, Old Red Sandstone; d, Post-Tertiary Gravels. 
and clays (d). Yet there can be no doubt that the interval separat- 
ing the epoch of the quartzite from that of the sandstone was brief 
when compared with the vast lapse of time that intervened between 
the nearly flat sandstones and overlying superficial deposits. It is 
by the evidence of organic remains that the relative importance 
of unconformabilities must be measured, as will be explained in 
Book V. 
Paramount though the effect of an unconformability may be in 
the geological structure of a country, it must nevertheless be, when 
viewed on the large scale, merely local. The disturbance by which 
it was produced can have affected but a comparatively circumscribed 
region, beyond the limits of which the continuity of sedimentation 
may have been undisturbed. We may therefore always expect to be 
able to fill up the gaps in one district or country from the more 
complete geological formations of another. 
