578 CHILI. 
together than c, d; but between d and e, for a like reason, the lamina- 
tion is parallel with d. Thus, in each of the cases stated, the lami- 
nation is parallel with the source of heat, or in other words, the 
crystals of mica have the vertical axis at right angles to the source of 
greatest heat. 
In the upper and under divergences of the intersection, the lamina- 
tion is curved so as to approximate to parallelism with the walls of the 
converging veins—the source of heat. This is shown in figures 7, 
8, and upper part of figure 6. In the lower part of figure 6, the veins 
are very unequal, and the consequence is that the lamination is 
parallel to the larger vein, and curves upward, and becomes nearly 
horizontal where it meets the small vein. 
To the left of the intersection, the lamination is nearly at right 
angles with the lower vein, or is but little oblique. ‘This appears to 
be determined, in part at least, by the original direction of the lamina- 
tion in the gneissoid granite. ‘T’o the right of the intersection, the 
lamination for a short distance is, in some cases, nearly parallel with 
the walls, and in others oblique, approaching to parallelism. 
The facts lead us to conclude that while the original direction of 
the lamination in the gneissoid granite has influenced the position of 
the mica formed near and within the veins, the heat of the veins was 
the more efficient cause determining its position; and it tended to 
give the crystals or scales of mica a position parallel with the heated 
vein, (or such that the vertical axis of the crystal should be at right 
angles to it,) in consequence of which, the lamination has the same 
direction. ‘The heat above and below the intersection would neces- 
sarily extend farther than on either side, and this may have been one 
cause of the greater influence in these parts. 
Veins of Hornblende Schist.—(F igs. 1, 2, 3, pages 562, 563.) ‘These 
veins, when small, resemble, in many points, the granitic veins. When 
large, they appear to form extensive beds. Whether injected or not in 
such a case, we have no facts to determine. The lamination parallel 
with the walls is seldom exemplified in trap dikes. - 
Decomposition of the Granite. 
The hills of the sea-coast are much rounded, owing to the ready 
decomposition of the gneissoid granite constituting them. ‘The rock 
is generally so deeply altered that it is difficult in any part to obtain 
