132 
GEOLOGY OF NORTH CAROLINA. 
and talcoid, and at two lines of outcrops less than a mile apart, and three 
to four miles from Raleigh, these slates become highly pumbaginous, the 
main seam of 12 to 20 inches in former case, and three feet in the other, 
containing 50 pier cent, and upwards of graphite. The more eastern of 
these beds is nearly vertical to 75° N. W., and the other 40° to G0°, 
probably forming an anticlinal, and a heavy body of micaceous white 
slaty quartzytes follows closely along the west side of the graphite. Alter- 
nations of argillaceous, talcoid and quartzytic beds continue for five and 
or six miles, when they disappear beneath a narrow trough of Triassic 
sandstones ; beyond which they emerge along an irregular, but approx- 
imately In. E. and S. W. line, in the great central mineral-bearing slate 
belt, so widely familiar to miners and geologists. This tract extends quite 
across the State in a breadth of 20 to 40 miles, and is composed of silic- 
ious slates and clay slates chiefly ; the former being often brecciated 
and conglomerate, the pebbles sometimes a toot and upwards in 
diameter, frequently chloritic, and often passing into hornstone and 
chert and occasionally into quartzyte. The clay slates are generally thin 
bedded, often shaly, grey, drab, banded, blue and frequently greenish, 
from an admixture of chlorite, sometimes talcoid or hydro-micaceous; and 
very often they may be better described as conglomerate slates, being 
composed of flattened and differently colored soft slaty fragments of 
all sizes, from minute particles to an inch and more in diameter. Rear 
the middle of the breadth of this body of slates in Montgomery county, 
in a very heavy ledge of silicious slates, occurs a silicious conglomerate 
which is filled for hundreds of feet with very singular silicious concretions, 
some of which Dr. Emmons has described under the name Palseotrochis ; 
but the rock for several miles, as well as at this particular locality, con- 
tains a multitude of rounded and ovoid masses from the smallest size to 
that of a hen’s egg ; showing the wide prevalence of conditions favorable 
to the operation of concretionary forces. 
Quite characteristic also of this bolt is the occurrence of extensive beds 
of pyrophyllyte slate, white and greenish, in places with disseminated 
crystals of chloritoid. Pyrophyllyte also occurs at several places in stellate- 
fibrous aggregations and also foliated like talc. 
The talcose, silicious and chlorotic slates are more abundant towards the 
base of the series, the east side, and the clay slates predominate on the 
west. 
A notable characteristic of this belt of rocks is the abundance of quartz 
veins, the fragments often covering and whitening the knolls and the 
roads for rods together, so that one can ascertain with considerable accu- 
racy when the boundary of these rocks has been passed by the sudden 
