W. M. Fonta’ne—Geology of the Blue Ridge. 21 
ranges called “Tobacco Row” and ‘‘No Business Mountains,” 
lying above Lynchburg on both sides of the James. 
The predominant rock along the railroad is a mica slate, and 
schist of varying character, but is mainly slate with micaceous 
matter in excess. The dip is usually high to the southeast. 
This is, however, not rarely reversed by the influence of the 
syenites. Near the eastern foot of the Blue Ridge, a very coarse 
gneiss is found. 
The railroad climbs the mountain to the height of about 
seven hundred feet, gradually passing inward over the east 
slope, so that the tunnel is cut through the center and crest of 
the range. The mountain proper in the vicinity of Rockfish 
Gap is composed of argillites, highly altered by local meta- 
morphism. Some very interesting effects are to be seen in 
passing over the eastern slopes. ‘The metamorphic agent seems 
to have acted more energetically in certain bands, making an 
acute angle with the general direction of the mountain. Along 
these bands the slates have lost their cleavage, and have become 
much impregnated with epidote, quartz and chlorite. These 
three minerals often form coneretionary masses, four to five feet 
im diameter, in which they are confusedly mixed together. 
Such lines of increased metamorphic action are, I think, deter- 
mined by crevices or breaks in the strata. 
The Blue Ridge at this point is a single chain, composed of 
highly altered argillites, with a central mass of eruptive rocks. 
/ommencing at the east entrance of the tunnel, which is seven- 
eighths of a mile long, we find the argillite in heavy beds, lying 
with a dip of about 50° to the southeast. These slates have a 
dark greenish-grey color, from the presence of films of chlorite. 
ey continue in the tunnel for about eight hundred and fifty 
yards, when we come upon an eruptive igneous rock, which ex- 
tends about one hundred yards. This is succeeded by argillites, 
which continue with the same southeast dip to the edge of the 
Silurian strata, which are found near the west entrance. The 
Southeast dip continues into the Silurian beds, but its steepness 
increases, 
_A belt of argillite on each side of the eruptive rock occurs, 
highly altered by the influence of the latter. In these belts the 
Slates lose their bedding and cleavage, resemble a compact 
mass of angular fragments, and become impregnated with 
various minerals. When not thus impregnated, the texture is 
crystalline, the color grey, and the rock becomes harder and 
enser. The altered belt on the west side is much wider than 
that on the east, being as much as one hundred and fifty yards. 
tn these altered belts occur many interesting associations of 
minerals, which can be well studied in the great mass of materi 
used in making the two approaches of the tunnel. 
