• GEOLOGY OF GILES COUNTY, VIRGINIA 
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1000 feet across, and numerous structures of a few feet each, 
mark the crest of the larger anticline and make measurements 
to determine the thickness of the Russell Formation highly un- 
satisfactory. The thickness, however, cannot be less than 300 
nor more than 400 feet. 
The formation clearly marks a transition period which may 
have introduced the time of erosion correlated with the lack of 
Middle Cambrian, and directly preceding the time of deeper seas 
prevalent during the formation of the Shenandoah Limestone. 
That the formation is a weak one is clearly shown by the num- 
erous folds throughout the entire thickness, some of which do not 
appear at all in the adjacent Shenandoah. It disintigrates rap- 
idly into a soil which is not as fertile as that resulting from the 
decomposition of the Chickamauga and Shenandoah Formations. 
The Russell Formation Subdivided" 
X. At the base of the Russell formation is a medium even- 
bedded limestone exposed along Walker Creek below Bane. It 
resembles the Shenandoah in some of its characteristics and is 
very different from the usual Russell. It runs under the typical 
Russell and is obviously older, but since its base is not exposed it 
may be a lens with more typical Russell underneath. For this 
reason this division is here called x and grouped under the head- 
ing of Russell. The color is blue to gray with red and purple 
lines and blotches which give the member a purple tinge. It is 
very hard and resistant because it is in part siliceous. Very fine 
crystalline to dense with weak irregular jointing. There are 
many branching calcite veins which are thin and thread-like in 
appearance. No chert nor fossils seen. Weathers dirty blue and 
black, rarely light blue. In the stream the red lines and blotches 
are emphasized by weathering so that the entire rock appears 
red. It is a ripple maker in the stream. 
Thickness 80-100 feet + 
1. CHOCOLATE, GREEN, AND BLUE SHALES 
Medium to thick bedded shales with prominent cross-bedding 
and jointing in all directions. There are a few master joints. 
There are also sandstone and limestone lenses, the latter of which 
are dense blue layers six inches to two feet in thickness and 
’ In all the subdivisions, the numbering is from the bottom up. 
