112 
NEWER PLIOCENE PERIOD. 
[Ch. IX. 
but are usually inclined at a very slight angle; they are seen 
to extend uninterruptedly from the base of the escarpment into 
the platform, showing distinctly that the lofty cliff was not 
produced by a fault or vertical shift of the beds, but by the 
removal of a considerable mass of rock. Hence we must con- 
clude that the sea, which is now undermining the cliffs of the 
Sicilian coast, reached at some former period the base of the 
precipice a, b, at which time the surface of the terrace c, b, must 
have constituted the bottom of the Mediterranean. Here, then, 
we have proofs of at least two elevations, but there may have 
been fifty others, for the encroachment of the sea tends to ob- 
literate all signs of a succession of cliffs. 
Suppose, for example, that a series of escarpments, e, /, g, h, 
once existed, and that during a long interval, free from subter- 
ranean movements, the sea had time to advance along: the line 
c, b, all those ancient cliffs must then have been swept away one 
after the other, and reduced to the single precipice a, b. There 
may have been an antecedent period when the sea advanced 
along the line h, I, substituting the single cliff e, I, for the series 
e > /» 9- 
We may also imagine that the present cliffs may be the 
result of the union of several lines of smaller cliffs and terraces, 
which may once have been produced by a succession of eleva- 
tory movements. For example, the waves may have carried 
away the cliffs k, i, in advancing to c, d. In the same manner 
they may ultimately remove the mass c, b, m, d, and then the 
platform c, 6, will disappear, and the precipice a, m, will be 
substituted for a, b. 
We have stated, in the first volume, that the waves washed 
the base of the inland cliff near Puzzuoli, in the Bay of Baise, 
within the historical era, and that the retiring of the sea was 
caused, in the sixteenth century, by an upheaving of the land 
to an elevation of twenty feet above its original level. At that 
period, a terrace twenty feet high in some parts., was laid dry 
between the sea and the cliff, but the Mediterranean is hasten- 
ing to resume its former position, when the terrace will be 
