288 GEOLOGICAL SURVEY 
be readily cut with the axe. J have seen chimnies, in Lexington, that have stood for 20 years, and 
the angles are now as sharp, and the impressions left by the chissel as fresh, as when they were 
put up. ‘To stand great pressure, this rock would require accurate dressing, as itis not very strong. 
From an analysis by Professor Shepard, its composition appears to be : 
WAG. - = nook HG Seep ocSorcose cosa SSsEeEeSSesesissessso45e 9.00 
Silicaeayae ste oss fC eale eee so sek ae. eee eee 77.50 
JNO), — een eepeetiaaote sea coseaeeecsssessS Gitassas 2.30 
IRrotoxide Of WON, -ss= = ase eee eee ans a eee ee 9.90 
Carbonate(of lime 22222 ee eeeee eee ee eee 1.3 
100.00 
I am inclined to think that the moderately hard marls of the Tertiary would also answer very 
well for certain architectural purposes, and I mentioned, in another place, that they had been applied. 
In Clarke county, Alabama, a white marl, much softer than that on the banks of the Ashley, is 
used for the construction of chimnies very generally. It resembles exactly the white Hocene marls 
of this State. It is so soft when first quarried, as to be cut with the drawing knife, and even planed ; 
and what is more remarkable, it stands fire admirably, provided that no water be thrown upon it 
while hot. 
As the mode of quarrying it is peculiar, it may be worth while to describe it. The face of the 
bluff, selected for the quarry, is cut into vertical pannels; the projecting portions being of the proper 
thickness for the blocks required, and as long as can be conveniently cut with a cross-cut saw. A 
small stream of water, from a barrel, is allowed to trickle down on the saw, which keeps it from clog- 
ging. When the slabis sawed, it is laid flat on the ground and cut, in the same manner, into blocks 
of the requisite size. ‘The length should not exceed double the thickness. The blocks are now 
dressed, and piled up loosely, and protected from rain, by a temporary covering ; after a partial dry- 
ing of this sort, they are ready for the mason, Any of the marls of the State, that are free from 
hard fossil shells, and sufficiently coherent to remain together, will answer for an experiment, which 
I trust some one will try. 
There is found on the sand hills a bed of ferruginous sand stone, which is very durable, because 
the iron is all peroxidised ; it is rough in appearance, but when dressed, forms a good material. In 
Fayetteville, N. Carolina, it is used extensively, and is even ornamental. 
F'LAGSTONES. 
Good flagstones are, in cities, of considerable value; I observed, in the Charleston Market House, 
flags that were imported from Yorkshire, England. These were transported by land, and canal, 
before they were shipped, a distance nearly as great as that from Charleston to Edgefield, where 
flagstones equally good may be found. F'lagstones, besides being durable, must split so as to leave 
smooth surfaces, that need little, if any, dressing. I have pointed out numerous localities, where 
the rocks present these conditions. The slaty gneiss of Edgefield; the talcose slates of Ruff’s 
Mountain, if they should be found sufficiently silicious ; the mica slates of York, near the Catawba; 
and those in Fairfield, on Dutchman’s creek, may be mentioned as favorable and accessible localities. 
There is a slaty rock passing into soapstone, along the King’s Mountain range, that can be pro- 
cured in large slabs; specimens may be seen in the church yards of the upper part of York, where 
itis used for tablets, and its dark gray and sombre color renders it conspicuous. 
