868 W. M. Fontaine—Primordial Strata of Virginia. 
The quartzites predominate in the lower beds. The kaolin 
shales often pass into a fine-grained sandstone, in which the 
grains = soe and kaolin of uniform size are re equally and uni- 
formly mixed. This latter rock, whic common in the 
Potedam of the northern part of the State, appears in great force 
at Rockfish Gap, and will be described in the section there more 
fu The strata of (10) are remarkable for their freedom 
from coloring matters, and for the thorough decomposition of 
the feldspathic matter present. The kaolin shales and shaly 
sandstones occur in plates of a few inches to a foot or more in 
in composition and texture than the siliceous layers w hich are 
of the disturbed rocks of the Silurian and Devonian areas i 
Virginia and elsewhere, where I have observed them. The 
usual effect on these shales of the Pitre eran. ne produced 
by disturbances is to cause them to assume more or less of the 
slaty cleavage, but I have never seen any ogi to general 
crystallization of the ies even in the most profoundly 
convulsed districts. Again, the change in the beds of sand- 
stone is as the eons lteadie of the ar hapa erains of 
san oreign material is introduced, it is always in 
the form of sea) impregnations, plainly ae es cirvalating 
heated waters. I will return to this we a he The strata 
of No. (11) do not require a further deseriptio 
The following section, No. I, represents ti strata from (1) 
to (8) inclusive. No. (8) rises in a cliff 200-800 feet high, 
leaning over in an arch toward the syenite. 
Srction I. (d) « 
©) O OOa9 O 
In this section, (a) A hv the bed of quartzite mentioned 
in a former paper, as occurring on the east side of the syenitic 
mountain, while (b) senies a portion of the mica slates which 
lean against this range on the east, with a southeast dip. The 
