126 
G-EOLO r OF NORTH CAROLINA. 
of tlie zone, across Gaston and Lincoln counties. A few miles west of this- 
is a narrow terrane of syenytes and other liornblendic rocks and granites, 
which extend northward across Lincoln and Catawba counties, reaching 
the Catawba river at the great bend. It is seen about 4 miles west of 
Lincolnton, at Newton, and in the railroad cuts near Catawba Station, and 
be} 7 ond. The predominance of liornblendic rocks, the absence of mica, 
and the general absence of stratification have seemed to justify the 
reference of this belt to the lower part of the series, along with the pre- 
ceding central zone. 
Preceding westward we find the rocks occasionally more micaceous, 
mica slates and slaty gneisses becoming in some localities cpiite common ; 
and there comes in along the centre and southern portions of the tract 
a series of mica schists and slates, some of which seem to be more or less 
talc-ose, and very felspatthic, which weather into a spongy, purplish- 
brown, soft rock, easily cut with the axe, which is much used for chim- 
neys, and as a substitute for soapstone. In places these slates are hard 
and abound in imperfect crystals of garnet, and occasionally of staurolite 
and cyanite. These rocks may be seen in the railroad cuts and hills 
about Hickory, and in the eastern ridges of the South .Mountains, and in 
the middle and southern parts of Polk county. It is noticeable that these 
schists and slates every where occupy the ridges and higher swells and do 
not reach the level of the river channels, so that they overlie the gneisses, 
and are to be referred to an upper division of this formation, or more 
probably to the next system, the Huronian. These rocks extend across 
the Catawba into Caldwell and Alexander counties and are seen in the 
southward spurs of the Brushy Mountains, from Gunpowder Creek to 
Middle Little River. The rocks of this tract are generally fine grained 
but toward the western side of it there is a body of coarse porphyritic 
grey gneiss, sometimes so rough and nodular as to appear like a con- 
glomerate, the nodules being lenticular and rounded masses of cleaveable 
felspar and cpiartz of various sizes, up to an inch and more in length, the 
dark gray argillaceous mica-schist matrix lapping around and enclosing 
them and filling up accurately the interstices, — a true augen-gneiss. This 
rock is seen conspicuously in the vertical and overhanging cliffs on the turn- 
pike just below Blowing Rock in Caldwell, in the steep mural ledge of 
Hickory Nut Mountain on Crooked Creek in McDowell, in the large 
masses of porphyroidal gneiss near Hickory Nut Gap, in the naked 
ledges about Flat Rock and the quarries near Hendersonville, and again 
on Little River near Jones’ Gap. And there is a wide belt of light 
colored fine-grained, very felspathic, easily decomposable gneiss, in Mc- 
Dowell county, very conspicuous in the railroad cuts about Marion, and for 
