GENERAL MEETING. 31 
seen that a vertical fault in easterly dipping strata, having its 
direction somewhat nearer the meridian than the present strike 
and its downthrow on the west side of the fault, would produce a 
lateral discontinuity like that here observed, the upthrown part of 
any stratum cropping out on the east of the downthrown part at a 
distance depending upon the amount of the vertical displacement. 
All this would depend upon whether the sand rocks were origi- 
nally continuous in the two ridges—a question which was left for 
the geologists to decide. The writer, however, took occasion to 
suggest that great longitudinal faults might be formed near coast 
lines when the gradual overloading of the balanced crust by depo- 
sitions of sediment produced a strain too great to be relieved by flex- 
ure. A rupture would then occur, the strata going:down on the 
overloaded side of the fault and up on the other until equilibrium of 
pressure upon the yielding magma below was restored by lateral 
displacement of the magma. The fault so formed would present a 
diminished resistance to dislocation, and if the action which origi- 
nated it should continue, it would be likely to increase in dimensions 
both in length and in the amount of vertical displacement. This 
action might even continue after the emergence of the region above 
the surface of the water, provided a more rapid denudation of the 
landward than of the seaward side of the fault took place, in which 
case a continued disturbance of equilibrium would be accompanied 
by vertical yielding, increasing the amount of dislocation, and by sub- 
terranean movements of the supporting magma, whereby a restora- 
tion of material would be effected from overloaded to denuded areas. 
Moreover, the hypothesis of a constant restoration of disturbed 
equilibrium makes it easier to understand why the folding of strata 
should grow steeper, even to a folding under, as the axis of a moun- 
tain chain is approached. A diagram exhibiting the so-called 
“fan-like structure of the Alps,” enlarged from a figure by Rogers, 
(see Rogers’ Report on the Geology of Pennsylvania, Vol. II, p. 
902,) was shown in illustration. The gradual subterranean move- 
ments inward under a mountain chain, as the upper portions were 
removed and the remainder elevated, would carry the strata along 
on a support of diminishing width until they were folded upward 
and backward. 
The gradual increase towards the east in the amount of corrugation 
and steepness of dips, together with the supposed reversed folding by 
which the rocks of the eastern part of the Appalachian region seem to 
