110 GEOLOGICAL SURVEY 
whole disintegrated in place, to a considerable depth ; and hence the broken surface of the country. 
On Dunean’s Creek the thick gneissoid strata, characteristic of the upper strata, make their appear- 
ance near the mill, where they are intersected by trap dykes of some extent. 
FarirFIELp, KERSHAW AND CHESTERFIELD DisrRIcts. 
There is but little in the geological features of Abbeville, Newberry, Fairfield, and the southern 
parts of Union and Laurens, to distinguish them from each other; and yet they are, in many 
respects, very dissimilar. 'The principal distinguishing features in the topography of Fairfield are 
due to the predominance of feldspar and hornblende in the rocks, and their consequent tendency to 
disintegration and waste. No small portion of the District presents a striking miniature representa- 
tion of a mountain region, that must be referred to this cause. Were particular examples necessary, 
one need only point to such localities as Montecello, Beaver Creek, the very streets of Winnsboro’, 
and the vicinity of Peay’s Ferry, where I saw whole fields in danger of being overspread by the 
debris from the granite on an adjoining hill side, which is brought down by every shower of rain. 
This cause renders it extremely difficult to point out the exact limits of the patches of true 
granite scattered over the District. The Montecello granite, with base of white feldspar, has black 
mica so disposed as to give the rock the appearance of marbled paper. In the northern part of the 
District numerous localities occur; and near Peay’s Ferry a crystalline granite, with reddish feld- 
spar, is seen, which resembles the Kershaw granite. 
But perhaps the geology of Fairfield will be best shown by tracing one or two sections, so as to 
exhibit the relations of the rocks to each other as they present themselves. 
After leaving the band of argillaceous rocks, in Richland, which has already been described, as 
it occurs in Edgefield and Lexington, we pass over the edges of strata of mica slate, intersected by 
veins of quartz; and occasionally, as we approach Montecello, it is interstratified with hornblende 
slate. Around that village the granite already mentioned is laid bare in masses upon the sur- 
face, but to a far greater extent on the declivities of the hills, where it may be examined in the ra- 
vines, and followed through every stage of disintegration. 
Associated with the trap found in the granite of this locality, there are others of sienite, composed 
of snow-white feldspar and crystals of hornblende, a continuation of one seen on the opposite side 
of the river, near the corner of Newberry and Lexington. Pursuing this section along the western 
side of the District, from Montecello to Beaver Creek, gneiss and hornblende are the prevailing rocks. 
Lhave more than once alluded to the fact that wherever gneiss is associated with hornblende, it 
becomes at once slaty; so that instead of the thick beds, characteristic of the gneiss in other parts 
of the State, we have fissile and highly laminated slates: and this part of the section presents 
numerous examples in illustration of this fact. Several extensive trap dykes are found here; one 
immediately after leaving Montecello, others on Terrible Creek; and to the left, near Ashford’s 
Ferry, they: are seen crossing the river. On Rock Creek a very considerable dyke may be seen, 
having its direction indicated by the usual globular masses of the rock strewed along the surface. 
On Beaver Creek it is difficult to say whether trap rocks or hornblende slates predominate—for it 
rarely happens that an opportunity offers of examining the rocks in their solid form; and although 
there is no mistaking the brownish soils of these rocks, still it is not always easy to distinguish 
