78 
AMERICAN GEOLOGY. 
New York. The line of demarkation between the two rocks is 
perfectly distinct. Its occurrence in veins in granite (figs. 7 and 
8) is conclusive of its igneous origin; it proves that like granite 
it has undergone fusion, and has been injected into cracks and 
fissures of the superincumbent rock. 
Fig. 7. 
Fig. 7.-—Ground plan of a system of veins in granite, as 
they occur at Gouverneur, St. Lawrence county, New York. 
These veins extend for many rods in length, and ramify in 
manner similar to granitic veins. Many localities occur in St. 
Lawrence, Jefferson, and Essex counties. They furnish an 
arrangement different from the foregoing, but in keeping 
with it. 
Fig. 8. 
Fig. 8 shows a vertical section of portions of the same vein, 
where they terminate laterally in a broken ledge of granite, 
showing that they descend into the mass of granite, or in other 
