t4t J. L. Campbell—Geology of Virginia. 
Ridges of this class generally lie off from one to several 
miles from the main range, and seem to have been thrust up 
beneath the limestones of the Canadian Period, the folds of 
which were probably much shattered at the time, and subse- 
quently worn or swept away, so as to leave the ridges of more 
durable sandstone naked for some distance down their steep 
sides, and flanked along both bases by slates and limestones— 
the latter often occupying narrow vaileys or troughs, like the 
one above described, or like Buford’s Valley in Bedford —_— 
traversed by the A. M. and O. RB. R., in going from Lynch- 
burg to Salem. | 
find fragments of metamorphosed slate, with both fragments 
tions I have given—especially on the first—have been sub- 
Jected to bending and pressure, and consequent friction, ought, 
according to the mechanical theory of metamorphism, to b 
ig strata. _ But no such effect has followed. The limestones 
have their fossils beautifully preserved. The sandstones have 
