650 
is simultaneously raised and depressed, so that it either 
overflows or returns into its own place again." It may 
be said, however, these were old — perhaps antidiluvian 
changes, and we are quite sure the earth has long stood 
firm. It will be well, therefore, to mention an instance 
of the subsidence and elevation of land during the 
historic period. Perhaps the most noted one is that which 
occurred at Pozzuoli, in the bay of Baiae, as indicated by the 
pillars of the temple of Jupiter Serapis at that place, and 
certified by documentary evidence. Originally, that temple 
of course was built above the level of the sea ; the site then 
sank twelve feet, so as to submerge its columns in a fresh- 
water deposit which protected them from future injury. 
The subsidence, however, continued, and then the sea swept 
over this newly-formed marshy surface, covering the columns 
of Jupiter's temple to a depth of nine feet more, and 
exposing them to the depredations of that destructive marine 
bivalve, the " Lithodomus " of Cuvier, from which they 
have greatly suffered. At one period then they were sunk 
twenty-one feet below the sea level,* leaving a little less than 
half of their original height above it ; but then another change 
began, and the flat shore where this temple stands gradually 
rose again ; a document of the reign of Ferdinand and 
Isabella of Spain, referring to a grant of land at Pozzuoli 
made to the University of that town " where the sea is 
drying up," and another of Ferdinand's alone, a little 
later, speaking of the same locale as one " where the ground 
was dried up." In the year 1538, the year of a great eruption 
of Vesuvius, the land about Pozzuoli rose rapidly, but it 
has since slightly sunk again, and now is apparently 
* Evidence of a most conclusive character was obtained by Mr. Babbage, as 
to the elevation of a considerable tract of land in the vicinity of this temple, at 
thirty-two feet above the present sea level, he having discovered a wave-worn 
line covered with barnacles, and pierced by boring testacea on the face of the 
banks above the tract of land lying below them. 
