134 
GEOLOGY OF NORTH CAROLINA. 
high angles, generally 45° to 80°. The clay slates are plumbaginous along 
the western side of the outcrop, and to the northward of Mt. Anderson 
is a bed of impure graphite, in places two and three feet thick. The 
limestone is gre}', bluish and light colored to white, and fine to coarse 
granular, schistose in structure, with tremolite, and disseminated crystals 
of iron pyrites. Some of these beds are dolomytic, as shown by the fol- 
lowing analysis by Dr. Genth, of a sample from a quarry near Lincoln- 
ton : 
Quartz and Silicates, 13. G2 
Carbonate of Lime, 4G.57 
Carbonate of Magnesia, 37. G3 
Carbonate of Manganese, 0.21 
Carbonate of Iron, 1.97 
The most valuable and characteristic mineral of the belt is magnetic 
iron, which is found throughout the length of it, cropping out at inter- 
vals of a few miles in large bedded veins, sometimes over 20 feet thick. 
The ore is usually granular and slaty, talcose or chloritic, and frequently 
more or less specular. At one of the largest veins it is highly epidotic. 
There are also frequent veins of limonite. 
In the direction of the continuation of the line of this belt, near the 
northern border of the State, in Surry and Stokes counties, is another 
body of quartzytes and mica slates, with occasional argillaceous and 
hydro-mica slates, constituting the range of the Pilot and Sauratown 
Mountains. Some of these quartzytes are flexible — itacolmnite, and 
there is a bed of conglomerate near the base of the series. The dip in 
the western part of the range of the Pilot is 17. W. about 20°, and in the 
eastern about the same amount, in the opposite direction ; and the easterly 
clip also holds for the Sauratown range ; while in the gap between, there 
is much less regularity, and the prevalent dip seems to be A. AY., and at 
angles varying between 30°an G0d°. 
The fourth belt of Huronian rocks is coincident in general direction, 
and partly in position, with the Blue Ridge. Towards the S. AY. it crosses 
that chain and ofcnpies a belt of two or three miles across the plateau of 
the upper French Broad; the rocks here being gray and bluish clay slates 
and hydro-mica slates, with very limited and occasional outcrops of 
quartzyte and of alight colored to gray and bluish schistose, compact to 
slightly granular limestone. AVith these are associated occasional beds of 
limonite. The rocks of this belt may be seen in Swannanoa Gap, in a 
large body of quartzo-argillaceous and quartzitic slates, and of mica slates 
