CHAPTER X. 
Tertiary formations of Campania — Comparison of the recorded changes in this 
region with those commemorated by geological monuments — Differences in the 
composition of Somma and Vesuvius: — Dikes of Somma, their origin — Cause 
of the parallelism of their opposite sides — Why coarser grained in the centre — 
Minor cones of the Phlegrsean Fields — Age of the volcanic and associated 
rocks of Campania — Organic remains — External configuration of the country, 
how produced — No signs of diluvial waves — Marine Newer Pliocene strata 
visible only in countries of earthquakes — Illustrations from Chili — Peru — . 
Parallel roads of Coquimbo — West-Indian archipelago — Honduras — East- 
Indian archipelago — Red Sea. 
TERTIARY FORMATIONS OF CAMPANIA. 
Comparison of recorded changes with those commemorated 
by geological monuments. — In the first volume we traced the 
various changes which the volcanic region of Naples is known 
to have undergone during the last 2000 years, and, imperfect 
as are our historical records, the aggregate effect of igneous 
and aqueous agency, during that period, was shown to be far 
from insignificant. The rise of the modern cone of Vesuvius, 
since the year 79, was the most memorable event during those 
twenty centuries ; but in addition to this remarkable pheno- 
menon, we enumerated the production of several new minor 
cones in Ischia, and of the Monte Nuovo, in the year 1538. 
We described the flowing of lava-currents upon the land and 
along the bottom of the sea, the showering down of volcanic 
sand, pumice, and scoriae, in such abundance that whole cities 
were buried,— the filling up or shoaling of certain tracts of the 
sea, and the transportation of tufaceous sediment by rivers and 
land-floods. We also explained the evidence in proof of a 
permanent alteration of the relative levels of the land and sea 
in several localities, and of the same tract having, near Puz- 
zuoli, been alternately upheaved, and depressed, to the amount 
of more than 20 feet. In connexion with these convulsions, 
