Gkology,] 
NATURAL HISTORY. 
595 
the actual condition of its surface, — that the phenomena 
just now described are nothing more than what was to be 
expected from previous induction. These facts, however, 
not only place beyond dispute the existence of such forces, 
— but show that, even in detaii, their effects accord most 
satisfactorily with the predictions of theory. It is not, 
therefore, at all unreasonable to conceive, that, in other 
situations, phenomena of the same character have been 
produced by the same cause, — though we may not at 
present be enabled to trace its connexion with the ex- 
isting appearances so distinctly; and though the facts, 
Avhen they occurred, may have been unnoticed, — or may 
have taken place at periods beyond the reach of histo- 
rical record, or even beyond the possibility of human tes- 
timony. 
M. Peron has attributed the great abundance of the 
modern breccia of New Holland to the large proportion 
of calcareous matter, principally in the form of comminuted 
shells, which is diffused through the siliceous sand of the 
shores in that country * ; and as the temperature, espe- 
cially of the summer, is very high on that part of the coast 
where this rock has been principally found, the increased 
solution of carbonate of lime by the percolating water, may 
possibly render its formation more abundant there, than in 
more temperate climates. But the true theory of these con- 
cretions, under any modification of temperature, is attended 
with considerable difficulty and it is certain that the 
process is far from being confined to the warmer lati- 
tudes. Dr. Paris has given an account of a modern for- 
mation of sand-stone on the northern coast of Cornwall t ; 
* Peron, Voyage, &c. ii. p. 116. 
t Trans, of the Geol. Soc. of Cornwall, vol. i. p. 1, &c. 
2 Q 2 
