W. M. Fontaine—Primordial Strata of Virginia. 417 
This rock is well exposed in a quarry near the railroad, from 
which a large amount of stone has been removed. Its 
structure and composition is thus fully exposed. It lies in 
massive plates five to six feet thick, with thin seams of shaly 
matter between several of the plates. These thin seams are the 
diminished representatives of the shales which separate the beds 
of conglomerate at Balcony Falls. Some small veins of quartz, 
the result of metamorphic action, fill cracks in the mass. The 
coarser materials are rounded grains of quarta of the size of a 
garden-pea and under. Rarely is a particle of fresh feldspar 
numerous grains and lumps of this feldspar, in a condition of 
almost complete decomposition, areseen. These larger particles 
are imbedded in a slaty cement of highly ferruginous, decom- 
posed, felsitie matter, which when scratched with a knife gives 
a decided cherry-red streak. Besides, distinct particles of 
hematite appear. Enclosures of angular fragments of the 
slates of the Blue Ridge are not rare. 
The more decomposed condition of this material in this 
y currents from the southwest, and or a considerable 
time subjected to agencies tending to disintegrate it. At 
Rockfish Gap the shores of th dial sea were probably 
sediment must have been rapidly formed and poured into the 
sea. I have already given some account of an eruptive syenite 
which, in the vicinity of the Peaks of Otter, has penetrated the 
older metamorphic syenites, and have stated also that the 
lowest Primordial rock at Balcony Falls has been highly altered 
by contact action of a similar rock. It is probable that this 
rock is the product of deep-seated metamorphic action, pro- 
duced by the sinking, in its earliest stages, of the bottom of 
the Primordial sea.. This would cause great pressure against 
the resisting syenitic border, and might fuse a portion of it 
and squeeze this out, shattering the Te and firmer mass. 
An igneous rock capable of delivering feldspathic and quartzose 
material exists also at Rockfish Gap, as is discl in the 
but if it was formed at this period, it probably caused a fractur- 
ing of the slates, which was the source of the fragments found 
in the conglomerate. The thickness of the conglomerate rock is 
60 feet, and like the two preceding, it has a dip of 70° to the 
