100 GEOLOGICAL SURVEY 
The result of the wasting action of water upon slightly cohering and finely divided matter, par- 
ticularly when aided by a considerable declivity, is truly astonishing. Deep ravines are excavated 
in an incredibly short time. The excavations are often deep enough to reach the level of the 
springs, and then, where there was at first but an intermitting cause of waste—the rains—there is 
now added a permanent one. Where the surface is protected by any less yielding material, there is 
an elevation left, while around it the excavation proceeds, and one is presented with the phe- 
nomenon of the formation of hill and valley, in miniature. It requires no effort of imagination 
to perceive how such causes, indefinitely continued, and acting under analogous conditions, may 
result in the present configuration of the surface of the country. Hills and valleys can only 
be the result of two causes: an elevatory force, which has raised up the hills, or a force which 
has scooped out the valleys. ‘The result of these two causes can easily be distinguished. In the 
former case, the rocks pushed up lean towards the line where the force acted; or, in other words, 
there is an anticlinal axis there. Instances of this sort I have already mentioned: the ridge run- 
ning across from Horse Creek to the Congaree is an example, and although not a very conspicuous 
one, was quite sufficient to produce considerable modifications of surface, as the turning aside the 
Saluda, whose course should have been along the bed of the Edisto. 'There are other more impor- 
tant efiects of this cause Seen among the spurs of the Blue Ridge; but even here the topographical 
features of the country are due to the joint action of both causes, rather than to one. Beyond 
these instances nearly all the irregularities of surface presented by the State, are the result of the 
other cause—the wasting action of water, and atmospheric agencies, or, as it is called, denudation. 
To have correct notions of the effects produced by denudation, it is only necessary to study a 
section of the rocks in any part of the region under consideration. Fig. 21 is a section represent- 
ing the disposition of the rocks between the villages of Edgefield and Abbeville. 
It is not necessary to turn aside from the road in order to observe, that the upturned edges of the 
rocks are exposed the whole distance, as seen along the undulating line s s s, which represents the 
surface of the country. Now I suppose it to be unnecessary to attempt to prove that rocks could 
not be deposited with their edges cut off in that manner: we can suppose no cause that could have 
produced such deposition. Besides, as we find the same strata upon opposite sides of the fold—and 
this is among the most common phenomena of geology—we are obliged to conclude that these 
strata were once continuous, as represented by the lines aa; and that that portion of the bent 
_strata between a and s must have been removed, in order to produce the appearances presented by 
the surface at present. It is also obvious that by noting carefully the thickness of the strata, and 
their angles of dip, and by joining the corresponding edges on opposite sides of lines of disturb- 
ance, it would be quite possible to approximate the restoration of the original surface of a 
