VERMONT VIRGINIA. 
Ill 
Analysis of Benson black roofing slate. 
SiO, (silica) 59. 70 
Ti0 2 (titanium dioxide, rutile) .. .79 
A1 2 3 (alumina) 16. 98 
Fe 2 3 (ferric oxide) 52 
FeO (ferrous oxide) 4. 88 
MnO (manganous oxide) 16 
NiO (nickelous oxide) Trace? 
CoO (cobaltous oxide) Trace? 
CaO (lime) 
BaO ( baryta) 
MgO ( magnesia) 
K 2 (potassa) 
Na 2 0(soda) 
1.27 
.08 
3.23 
3.77 
1.35 
Li 2 (lithia) Strong trace. 
H 2 (water below 110° C. ) .30 
H 2 (water above 1 10° C.) 3. 82 
P 2 5 (phosphoric oxide) p; 
C0 2 (carbon dioxide) 1. 40 
FeS 2 (pyrite) L. 18 
S0 3 (sulphuric oxide) Trace. 
C (carbon) 4(5 
Total L00. 05 
S (total sulphur included above) . . 63 
Specific gravity 2. 7748 
The more important features of all these Vermont slates, as brought out in the 
above descriptions, will be found in tabular form opposite page 124. 
VIRGINIA. 
By T. Nelson Dale. 
W. B. Rogers, in his reports to the legislature of Virginia during the years 1835 to 
1841, « called attention to the slate deposits east of the Blue Ridge in Buckingham, 
Fluvanna, and Fauquier counties. Slate also occurs in the Blue Ridge in Amherst 
County. 
Geological relations in Buckingham and Fluvanna counties. — Rogers' reference to this 
slate & may well be repeated here : 
This (roofing slate) makes its appearance on both sides of the James River. ... In Bucking- 
ham the bed is largely exposed in the neighborhood of New Canton, on Slate River. ... In tex- 
ture, density, and capacity of resisting atmospheric agents it can scarcely be excelled by a similar 
material in any part of the world. This quarry was first opened to procure slate for roofing the Cap- 
itol, and notwithstanding it has been thus long known and its value established, but little further 
use has been made of it until the activity of the present owner has again brought it into notice. The 
building of the university will soon be furnished with a complete covering of slate from this quarry. 
Slate River empties into the James about 40 miles west-northwest of Richmond 
and 52 miles northeast of Lynchburg. The extent and structure of the formation 
which includes these slate beds require further study, but fig. 12 will serve to show 
some of its important features. The width of the formation north of the James, as tat- 
as explored by the writer during 'a very brief visit, extends from a point one-half 
mile west of Bremo Bluff to a small creek entering the James If miles east-south- 
east of Shores, a distance of If miles. It strikes about south-southwest across the 
James, having a minimum length of 4 miles. South of the James its eastern bound- 
ary lies about 3,000 feet west of the toll bridge opposite Bremo Bluff, and its western 
boundary is roughly one-fourth mile east of the Virginia Mills, on Slate River. The 
"Bremo Bluffs," on the north side of the James, and those at New Canton, on the 
south side, both consist of quartzite with like strike and dip— N. 17°-23° E., dip 65° 
E. and 90°, on the north, and N. 13°-18° E., dip 90°, on the south. The exposure of 
(quartzite on the north is about 950 feet across the strike and on the south about 3,000 
feet. These facts and the jagged structure of the 75-foot high "Bremo Bluff" show 
that the James here flows through a broad transverse cut in the quartzite and the 
slate formation west of it. This quartzite is finegrained, muscovitic, and biotitic, 
with an occasional plate of calcite and a few fragments of plagioclase. It is inter- 
a See Bibliography, p. 145. 
Bull. 275—06—9 
{>Op. cit., p. 79, 
