530 
ELEMENTS OF GEOLOGY. 
these breccias are many angular and hardened fragments of 
laminated clay in different states of alteration by heat, and 
intermixed with volcanic sands. 
The loftiest of the Cyclopean islets, or rather rocks, is 
about 200 feet in height, the summit being formed of a mass 
Fig. 599. 
Fig. 600. 
of stratified clay, the laminae of which are occasionally sub¬ 
divided by thin arenaceous layers. These strata dip to the 
N.W., and rest on a mass of columnar lava (see Fig. 599) in 
which the tops of the pillars are weathered, and so rounded 
as to be often hemispherical. In 
some places in the adjoining and 
largest islet of the group, which 
lies to the north-eastward of that 
represented in the drawing (Fig. 
599), the overlying clay has been 
greatly altered and hardened by 
the igneous rock, and occasionally 
contorted in the most extraordinary 
manner; yet the lamination has not 
been obliterated, but, on the con¬ 
trary, rendered much more conspic¬ 
uous, by the indurating process. 
In the wood-cut (Fig. 600), I have 
represented a portion of the altered 
rock, a few feet square, w^here the 
alternating thin laminae of sand and 
clay are contorted in a manner often 
p f + • 1 I- observed in ancient metamorphic 
Contortions of strata ID the largest ^ ^ t. 
of the Cyclopean Islands. schists. A great iissure, running 
