W. M. Fontaine—Geology of the Blue Ridge. 15 
The lower chain ou the east leaves the immediate vicinity of 
the Blue Ridge in Maryland, diverging more and more as it 
passes through Virginia, so as to embrace a belt of the country 
which widens to the south. This chain has a variety of names, 
according to the locality. In Maryland and Northern Virginia 
it is called “Catoctin,” but farther southwest in Virginia, “ Bull 
Run.” It is then broken up into a number of isolated moun- 
tains for a considerable distance, reappearing as the ‘ South- 
west,” and “Green Mountains,” in Albemarle County. Near 
Lynchburg, Va., it is called “ Buffalo Ridge ;” and southwest of 
this place, it is again dispersed into isolated ridges and peaks. 
For the sake of convenience, I shall call this entire range by 
its more northerly name, “Catoctin.” 
The valley between these ranges presents its simplest topog- 
taphy to the north. It is there occupied mainly by isolated 
hills of considerable magnitude and by some connected chains 
of the same. Farther to the southwest, mountains both isolated 
and in short ranges appear in the central portions. Neur Char- 
lottesville, Albemarle County, these attain considerable dimen- 
Sions and continue with increasing force to beyond Lynchburg, 
a distance of more than sixty miles. Near Lynchburg the 
valley obtains its maximum width of about twenty-five miles. 
The most northerly portion of this belt examined by me was 
at “Point of Rocks,” Maryland, and at “Harper's Ferry.” In 
order to give some idea of the portions of the entire belt not ex- 
amined by myself, I shall quote from Professor Wm. B. Rogers’ 
Virginia Reports; all the more freely, as they unfortunately 
never have been published. 
At Point of Rocks, on the Baltimore and Ohio Railroad, we 
have a splendid exposure of the rocks, both in the tunnel 
through the mountain and in the cuttings for the canal. The 
rocks com osing the Catoctin Mountains here are, in their least 
altered condition, well defined argillites. This particular variety 
orms a very important feature in the geology of the northern part 
of the Blue Ridge. Its lithological features We so pronounced 
