W. M. Fontaine—Primordial Strata of Virginia. 419 
slates or shales, in which the dip rises to 75° to the southeast. 
These slates, which in fact are highly compressed eri are 
in places much crushed, and show on their faces fine wrinkles. 
They are 300 feet thick. We then have 80 feet of iocureiel 
brown sandstone, with some chlorite, and a good deal of 
partly decomposed feldspar interspersed i in it. Then an interval 
of concealed rock occurs for 100 feet. We then have for 150 
with greenish shaly beds, in which the dip comes down to 
50° southeast. Then very finely Seale pink-colored slaty 
shales, which weather purplish red. Thickness 200 
About 50 feet (on the east side) of these shales differ from the 
rest in color alone, being greenish when fresh, and taking a 
yellow tint on weathering. “Then for 100 Leo a ‘bluish shale i is 
found. The two last series of beds, (5) and (6), appear to be 
the equivalent of No. (9) at Balcony Falls, Their combined 
thickness is about 1450 feet, that i is, provided no reduplication 
from folding occurs. This is possible, though not probable, I 
think. It will be seen that these rocks are characterized by 
the large amount of ferruginous matter which they contain, by 
which they are i distinguished from those which precede 
and follow t 
(7.) The ri: in se mio series gradually declines until 
it attains on the west side 40° S.E., which is still more de- 
creased in No. (7), ie it varies from 30° to 40° S. The 
strata now to be described are the equivalent of the Potsdam 
sandstone, and resemble No. (10) at Baleony Falls in their 
almost total freedom from iron and other coloring matters, also 
in the great amount of siliceous matter and kaolin present in 
them. But while at Balcony Falls we find many layers of 
very considerable thickness to be pure cde all the strata 
here have some kaolin, and — substance forms by far = 
greater part of the rock. The system here consists of a 
number of thin —— in oh i we may cep a ‘three 
lin sandstone, th cute: grains being now eon to the 
naked eye. The kaolin still peelbaccios but this rock occurs 
in slabs four to eight inches thick, and with a, forms layers or 
beds interstratified with c, which is a banlin sandstone of 
moderately fine grain, and has often a thickness of several feet 
in the individual layers. The quartz grains are mixed with an 
equal amount of kaolin, which here serves as a cement for 
them, and forms a peculiar, eae looking rock, which can be 
easily crushed and crumbl a loose grit. All of these 
varieties assumed a drab or fa yellow color on weathering, 
