[ 59 ° ] 
of a foot or more, intirely petrified and reduced 
into marble. At lefs than the depth of a foot they 
approach nearer to their natural date. And at the 
furface of this cruft, they are either dead, though ex- 
tremely well preferved, or ftill living. 
This obfervation demonftrates, that ftones or pe- 
trifactions may be formed, and actually are formed, 
in great quantities under the water. 
It is to be remarked, that thefe cruftaceous and 
teftaceous bodies and beds of polypes, mentioned 
above, are every-where mingled in the utmoft 
confulion with each other: which thews a ftriking 
refemblance between the cruft difeovered at the bot- 
tom of the lea, and thofe of the marine bodies petri- 
fied, found in many parts under the earth, and efpe- 
cialiy in Italy. If thefe marine bodies petrified are 
naturally in that confulion in the fea ; if they were 
born and die ; and if they have been petrified in that 
ftate; it is highly probable, that thofe, which are 
found under-ground in the ftrata in fuch confufion, 
are likewife placed naturally in the fame manner un- 
der the fea, when it covers them, and not by means 
of extraordinary events, fuch as volcanos and earth- 
quakes, as has been conjectured. 
The more thefe teftaceous and cruftaceous bodies 
and beds of polypes multiply, the more their exuviae 
and fkeletons contribute to inlarge this cruft difeo- 
vered at the bottom of the fea. Dr. Donati remarked, 
that in feveral parts it formed very confiderable banks, 
and of a very great thicknefs. 
It follows from hence, that the bottom of the fea 
is conftantly rifing higher and higher. Divers other 
caufes contribute to it. Snow and rain waters bring 
down 
8 
