CHAPTER XI. 
Newer Pliocene fresh-water formations — Valley of the Elsa — Travertius of Rome 
— Osseous breccias — Sicily — Caves near Palermo — Extinct animals in newer 
Pliocene breccias — Fossil bones of Marsupial animals in Australian caves — 
Formation of osseous breccias in the Morea — Newer Pliocene alluviums — 
Difference between alluviums and regular subaqueous strata — The former of 
various ages — Marine alluvium — Grooved surface of rocks — Erratic blocks of 
the Alps — Theory of deluges caused by paroxysmal elerations untenable — ■ 
How ice may have contributed to transport large blocks from the Alps — Euro- 
pean alluviums chiefly tertiary — Newer Pliocene in Sicily — Loss of the Valley 
of the Rhine — Its origin — Contains recent shells. 
FRESH-WATER FORMATIONS. 
In this chapter we shall treat of the fresh-water formations, 
and of the cave breccias and alluviums of the newer Pliocene 
period. 
In regard to the first of these, they must have been formed, 
in greater or less quantity, in nearly all the existing lakes of 
the world, in those, at least, of which the basins were formed 
before the earth was tenanted by man. If the great lakes of 
North America originated before that era, the sedimentary 
strata deposited therein, in the ages immediately antecedent, 
would, according to the terms of our definition, belong to the 
newer Pliocene period. 
Valley of the Elsa. — As an example of the strata of this age, 
which have been exposed to view in consequence of the drain- 
age of a lake, we may mention those of the valley of the Elsa, 
in Tuscany, between Florence and Sienna, where we meet with 
fresh-water marls and travertins full of shells, belonging to 
species which now live in the lakes and rivers of Italy. Valleys 
several hundred feet deep have been excavated through the 
lacustrine beds, and the ancient town of Colle stands on a hill 
composed of them. The subjacent formation consists of ma- 
rine Subapennine beds, in which more than half the shells are 
