170 EFFECTS of HEAT 
ned to his native fpot, can form no idea of thofe truths, 
which at every ftep in an alpine diftri@ force themfelves 
on the mind of a geological obferver. Unfortunately for 
the progrefs of geology, both London and Paris, are pla- 
ced in countries of little intereft; and thofe fcenes by which 
the principles of this fcience are brought into view in the 
moft ftriking manner, are unknown to many perfons beft 
capable of appreciating their value. The moft important, 
and at the fame time, the moft aftonifhing truth which we 
learn by any geological obfervations, is, that rocks and moun- 
tains now placed at an elevation of more than two miles 
above the level of the fea, muft at one period have lain at 
its bottom. This is undoubtedly true of thofe ftrata of lime- 
{tone which contain fhells ; and the fame conclufion muft be ex- 
tended to the circumjacent ftrata. The imagination ftruggles 
againft the admiflion of fo violent a pofition ; but muft yield 
to the force of unqueftionable evidence ; and it is proved by 
the example of the moft eminent and cautious obfervers, that 
the conclufion is inevitable *. 
ANOTHER queftion here occurs, which has been well treat- 
ed by Mr Pirayrair. Has the fea retreated from the moun- 
tains? or have they rifen out of the fea? He has fhewn, 
that the balance of probability is incomparably in favour of 
the latter fuppofition ; fince, in order to maintain the former, 
we mutt difpofe of an enormous mafs of fea, whofe depth 
is feveral miles, and whofe bafe is greater than the furface 
of the whole fea. Whereas the elevation of a continent 
out of a fea like ours, would not change its level above a 
few feet; and even were a great derangement thus occa- 
fioned, 
* Saussure, Voyages dans les Alpes,tom. ii. p. 99.—104. 
a 
