W. M. Fontaine—Geology of the Blue Ridge. 95 
of taleose matter with specular and magnetic iron, containing 
sometimes enough of the latter to be worked as an ore 
along James River 
Returning to the latter place, we find, as we proceed up 
stream, numerous ledges of this rock succeeding each other at 
short intervals, being overlaid unconformably by mica slate, 
Which passes oceasionally into mica schist. These ledges oc- 
cupy a belt extending to the west some five or six miles, but 
diminish in frequency westward until mica slates again oc- 
® rock sometimes breaks through the slates, and one ledge 
tyverses the dip developed by its neighbor, crumpling back the 
ss contorting and crushing them. The width varies greatly. 
“Aw one ledge 600 feet wide near the town, but many are no 
more than 100 feet wide. 
a "he principal component is hornblende, in pretty large crys- 
line particles, imbedded in a rather scanty cement of fine 
granular, white feldspar. This is too fine to show crystalline 
= es, and hence the species could not be determined. Taking 
the features all together, it most resembles a syenite, formed by 
ose, none of the omponents are perfectly crystallized, or 
‘ - . 
cone ether, and hence perhaps the ease with which it de- 
