74 GEOLOGICAL SURVEY i 
slices from the face of the escarpments, by what may be termed exfoliation on a grand_scale. 
Both at Cesar’s Head and Table-rock immense tablets may be seen standing erect, as they dropped 
from the face of the rocks. 
Towards the West, beyond the Jocassa Valley, the mountains, capped with these enormous strata, 
leave the State and are succeded by a series of hills, covered with mica slates. 
HorNBLENDE SLATE. 
This rock, which is a slaty compound of feldspar and hornblende, is often found passing into 
gneiss, and alternating with it; and, although it occupies no very great or continuous area in the 
State, it holds quite an important place in relation to the soils of the Districts where it occurs.— 
The connection of this rock with gneiss has already been shown, and where they alternate the latter 
rock always assumes a slaty structure. All rocks containing hornblende are, in a peculiar degree, 
subject to disintegration, from the decomposition of that mineral. It generally occurs in fissile beds ; 
it is sometimes quite tough, and the feldspar is often absent. Along the base of the mountains, 
‘from the upper part of Spartanburg District to Oconee Station in Pickens, a wide belt of this rock 
occurs. It passes into a slaty hypersthene rock, which may be distinguished by its bluish, bronze 
lustre. About ten miles north of Greenville a strip of hornblende slate may be traced east, to the 
branches of Tyger, and from Pendleton to West Union alternations of the rock occur nearly all 
the way. There are numerous other localities, some of which will be noticed in another place; 
but it would be tedious, as well as useless, to enumerate all the isolated patches of this, and other 
rocks, that are scattered over the State. 
Mica SLate. 
Judging from the wide-spread localities of this rock, it must once have occupied no small portion 
of the upper part of the State. It is found in spots of limited extent, from the Tertiary boundary 
to the mountains. It alternates with gneiss and hornblende, but it is not before we reach Pickens 
that we find it occupying any considerable portion of the surface of the country. In the N. W. 
corner of the State it is the prevailing rock, and has given a soft and rounded character to the hills 
of that region, which, instead of the long ridges of the gneiss, appear in the form of smooth, 
rounded knobs. Very similar to this is the region around the Cowpens, in Spartanburg District. 
The surface is covered with small, lenticular bits of quartz, coated with mica, which are left after 
the finer particles are washed away. The Districts where mica slate prevails, although undulating, 
are rarely so much broken as those Districts where the other rocks abound, for the reason that it is 
not so easily disintegrated. There are several little mountain knobs scattered over the State, which 
are principally composed of this rock, such as Ruff’s Mountain, Gelkey’s Mountain, and Henry’s 
Knob; but these, and other localities, will be noticed in another place. 
Mica slate is found passing, by insensible degrees, into talcose slate, by the substitution of tale 
for mica; when both minerals are found in the same rock, it is called taleo-micaceous slate. 'This 
and the talcose slates are confined to that portion of the State known as the gold region, and to the 
belt in York and Spartanburg that contains the magnetic iron ores. he finest specimens of tal- 
