GEOLOGY OF GILES COUNTY, VIRGINIA 
347 
Fossils are rare, but some specimens of Lingula cuneata can 
be found in the shaly division. Excellent specimens of Scolithus 
verticalis and Arthrophycus harlani have been found on Angels 
Rest and Peters slopes. What faunal evidence can be found then, 
as well as stratigraphic position and lithologic character, seem 
to indicate Medina age for the Clinch. 
The Clinch probably rests unconforniably upon the upper 
Ordovician Bays sandstone. 
The Clinch Sandstone Formation Subdivided 
Narrows Section 
1. Lower part of Clinch, Sandstone in layers from one inch 
to eight feet, with thin arenaceous shale partings, one-fourth to 
three inches in thickness. Colors are gray and greenish blue as 
well as a purplish gray and it is not until weathered that the 
formation assumes the bronze red tint due to the iron impurities. 
Quartz pebbles cemented with iron, silica and colored by the iron 
are metamorphosed into a fair quartzite. The pebbles attain a 
size commonly equal to that of a hickory nut, rarely 2-3 inches 
in diameter, and are of older quartzite and vein quartz. There 
are some minor faults in this division, 120 feet. 
2. Upper layers. Five shale layers, nearly four feet thick, all 
arenaceous, in variegated colors of green, blue, red and brown as 
well as various tints, and being thinly laminated — separated by 
four layers of quartzitic gray sandstone of about six inches in 
thickness. These beds vary notably from place to place. 
20 feet. 
The Rockwood Formation 
This formation takes its name from Rockwood, Tennessee, 
where it has been used as an iron ore for many years. It is a 
heterogeneous mass of shales and sandstones, corresponding to 
the Clinton formation with its iron ore of New York and Ala- 
bama. In the Narrows of the New River, 292 feet of this forma- 
tion are exposed but in some localities its thickness runs as high 
as 400 feet. 
In some places, the sandstone is semiquartzitic, and such a 
layer forms the upper rapids in the New River at the Narrows. 
The jointing is good and is for the most part cuboidal. The dom- 
inant color of the formation is red on account of the large iron 
content. These rocks are fossiliferous to some extent, fucoids. 
