72 
NEWER PLIOCENE PERIOD. 
[Ch. VI. 
No. 9. 
Section of calcareous grit and pcperino, east of Pu/ugo?iia. South side of jmss. 
Vertical height about thirty feet. 
No. 10. 
Section of the same beds on the north, side of the pass. 
The disposition of the strata, on both sides of the pass, is most 
singular, and remarkably well exposed, as the harder layers 
have resisted the weathering of the atmosphere and project in 
relief. The sections exhibited on both sides of the pass are 
nearly verticaL, and do not exactly correspond, as will be seen 
in the annexed diagrams (Nos. 9 and 10). It is somewhat 
difficult to conceive in what manner this arrangement of the 
layers was occasioned, but we may, perhaps, suppose it to have 
arisen from the throwing down of calcareous sand and volcanic 
matter, upon steep slanting banks at the bottom of the sea, in 
which case they might have accumulated at various angles of 
between thirty and fifty degrees, as may be frequently seen in 
the sections of volcanic cones in Ischia and elsewhere. The 
denuding power of the waves may, then, have cut off the upper 
