so 
NEWER PLIOCENE PERIOD. 
[Ch. VII. 
This theory of the intrusion of the basalt is confirmed by the 
fact, that in some places the clay has been greatly altered, and 
hardened by the action of heat, and occasionally contorted in 
the most extraordinary manner, the lamination not having been 
obliterated, but, on the contrary, rendered much more con- 
spicuous by the indurating process. 
The annexed wood-cut (No. 15) is a careful representation 
of a portion of the altered rock, a few feet square, where the 
alternate thin lamina? of sand and clay have put on the appear- 
ance which we often observe in some of the most contorted of 
the primary schists. 
No. 15. 
Contortions in the newer Pliocene strata, Isle of Cyclops. 
A great fissure, running from east to west, nearly divides 
the island into two parts, and lays open its internal structure. 
In the section thus exhibited, a dike of lava is seen, first cut- 
ting through an older mass of lava, and then penetrating the 
superincumbent tertiary strata. In one locality, the lava rami- 
fies and terminates in thin veins, from a few feet to a few inches 
in thickness (see diagram No. 16). 
