ards the southern end. The Apennines, indeed,
consist almost entirely of Mesozoic and Tertiary beds, like the outer
zones of the Alps. Remnants of a former inner zone of more ancient rocks
may be seen in the Apuan Alps, in the islands off the Tuscan coast; in
the Catena Metallifera, Cape Circeo and the island of Zannone, as well
as in the Calabrian peninsula. These remnants lie at a comparatively low
level, and excepting the Apuan Alps and the Calabrian peninsula they do
not now form any part of the Apennine chain. But that in Tertiary times
there was a high interior zone of crystalline rocks is indicated by the
character of the Eocene beds in the southern Apennines. These are formed
to a large extent of thick conglomerates which are full of pebbles and
boulders of granite and schist. Many of the boulders are of considerable
size and they are often still angular. There is now no crystalline
region from which they could reach their present position; and this and
other considerations have led the followers of E. Suess to conclude that
even in Tertiary times a large land mass consisting of ancient rocks
occupied the space which is now covered by the southern portion of the
Tyrrhenian Sea. This old land mass has been called Tyrrhenis, and
probably extended from Sicily into Latium and as far west as Sardinia.
On the Italian border of this land there was raised a mountain chain
with an inner crystalline zone and an outer zone of Mesozoic and
Tertiary beds. Subsequent faulting has caused the subsidence of the
greater part of Tyrrhenis, including nearly the whole of the inner zone
of the mountain chain, and has left only the outer zones standing as the
present Apennines.

Be this as it may, the Apennines, excepting in Calabria, are formed
chiefly of Triassic, Jurassic, Cretaceous, Eocene and Miocene beds. In
the south the deposits, from the Trias to the middle Eocene, consist
mainly of limestones, and were laid down, with a few slight
interruptions, upon a quietly subsiding sea-floor. In the later part of
the Eocene period began the folding which gave rise to the existing
chain. The sea grew shallow, the deposits became conglomeratic and
shaly, volcanic eruptions began, and the present folds of the Apennines
were initiated. The folding and consequent elevation went on until the
close of the Miocene period when a considerable subsidence took place
and the Pliocene sea overspread the lower portions of the range.
Subsequent elevat