20 W. M. Fontaine—Geology of the Blue Ridge. 
morphic products is no doubt due to the presence of true igne- 
ous rocks in this region. Rogers mentions their existence, but 
does not describe them. 
say Chesapeake and Ohio a crosses the Catoctin 
tains (here called “ sabato Ae ut two miles east of 
Pa doteaville at Shadwell, which is eto on the Rivanna 
River. The stream has cuta passage through the range, expos- 
ing the rocks in its bed. The structure here is essentially the 
same with that seen at Pointof Rocks. A series of closed folds 
give a succession of southeast dips. The material composing 
the mountain, however, is no longer argillite, but a more massive 
argillaceous quartzite, of greenish color, from the great amount 
of chlorite and epidote developed in it. This mass, when more 
highly altered, resembles very closely a true — rock, and 
is the material calle by Rogers ‘epidotic roc n passing 
out of the region of argillites of the north jabs othe quartzites of 
the more southern district, we note thus a change in the struc- 
ture of the Catoctin with respect to the nature of the strata. We 
still find a metamorphic product like that at Point of Rocks, 
only here with much more epidote. This, however, does not 
form any portion of the higher ground, called mountains in this 
section, but lies a short distance west of it, acting as the dis- 
turber and metamorphoser of the quartzite, which usually com- 
poses the mountains. ‘The latter rock general y dips away from 
the epidosites (as we may call them), or stands vertically, and 
by its superior hardness has resisted erosion better. 
The railroad crosses the valley nearly at right angles to the 
strike. By following it we get a tolerably good exposure of 
the strata. Just west of Charlottesville the first of a series of 
ledges of syenite is crossed. This rock, which abounds through- 
out the central portion of the valley, as far as Lynchburg, dis- 
tant eee) miles, will be described in the account of the strata at 
that place. 
The succession of rocks mentioned above as met with 1 
going from east to west, in the district to the northeast of Char- 
lottesville, occurs here also. We find, however, more abundant 
quartzites, and these of gneissoid character, extending farther 
west of the Catoctin range into the central parts of the valley. 
These quartzites play an important part in the structure of the 
of mountains, which, commencing to the southwest 
of Charlottesville, and occupying the center of the valley, ex- 
tend as - as Lynchburg. They are called near Charlottesville 
“The Ragged Mountains.” Formed of a capping of quartzite, 
diacinbad by the syenites, they assume the character of short 
ranges confusedly arranged. ‘Toward Lynchburg they are less 
largely composed of stratified rocks. Various coarse granites 
sat syenites make up most of their mass, especially in the short 
