OF SOUTH CAROLINA. 118 
red and yellow ochre. Immediately on the banks of the creek trap rocks may be traced in a direc- 
tion N.50° BE. At the mill, near the village, beds of highly inclined silicious rocks occur, that resem- 
ble gray wacke, and belong probably to the paleozoie rocks. I could find no fossils in them, not- 
withstanding that I made diligent search for them. Similar rocks occur in North Carolina, not far 
from the line; but I am not aware that any organic remains have been discovered in them. 
In South Carolina it is difficult to ascertain the relative position of these rocks, as nearly the 
whole of the region in which they occur is covered by beds of sand; and it is only on one or two 
streams, where the latter are removed, that they are seen at all. 
At Mount Crogan the Tertiary deposits terminate, and we have again the usual argillaceous 
rocks, which occupy this part of the District till they are covered by the New Red sandstone, on 
Clay Creek. 
I ascertained the curious fact that the air, in wells recently dug in the argillaceous rocks of this 
region, becomes so foul, that it becomes necessary to resort to artificial means of ventilation before 
the men can proceed with the work. TI think it highly probable that this result is due to the absorp- 
tion of oxygen by the clay slates. Humboldt has recorded a similar instance, where the air, in 
certain mines, became so deoxidised by this cause, as to be irrespirable. 
In old wells it is quite common for carbonic acid to accumulate, but in wells in the progress of 
construction it is not easy to suppose such a cause, in this region, as the evolution of that gas. 
At Slate-ford, on Lynch’s Creek, the argillaceous rocks are again brought to the surface, by denu- 
dation; and between Fork Creek and Lynch’s Creek they are seen reposing against the talco-mica- 
ceous rocks of the gold formation. It is here that the remarkable mine, known as Brewer's, occurs, 
which has been described at length in another place. , 
The strip of New Red sandstone that comes into the State, extends from the line a distance of 
five miles. It is composed of quartzose particles, cemented by red ferruginous clay, varying in 
color from a brick-red to yellowish gray. On clay Creek the solid ledges of the rock are found out- 
cropping, Which are quarried for building materials, and sometimes for grindstones. One of the 
most interesting features in the geology of this part of the District is found in the trap dykes, which 
may be traced for miles by the black streaks they have produced by the alteration of the sandstone. 
ABBEVILLE. 
From the manner in which the subjacent granite rocks of these Districts are laid bare, by the 
removal of the metamorphic slates, by denudation from their prominent and irregular points, it is 
obvious that their surface must be constantly increasing, in proportion to the destruction of the 
slates. It appears that the granitic foundation upon which the superincumbent rocks were depo- 
sited, was exceedingly uneven—so that the prominent points would first be reached by denudation, 
while the depressions would yet remain covered up. 
Numerous examples of true granite are found in Abbeville at distant localities: on the South be- 
tween Hard-labor and Long-cane; on the South-east, along the Saluda, from the line to Swansey’s 
Ferry. On the weathered surface of the rocks exposed here, a lively imagination could readily con- 
vert the effects of decomposition into foot-prints of various animals. Very similar to these are the 
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