342 
■run GEOLOGIST. 
Taking the two classes togetlier as representing tliirty distinct 
series of cavernous localities, one is found in the New Red Sandstone 
formation, two in the Carboniferous, two in the Devonian or Old 
Red, seven in the limestones of the Upper, two in those of the 
Middle, and six in those of the Lower Silurian formation, three in 
the Huronian rocks of Sir William Logan, and seven in the Lauren- 
tian rocks of the same geologist. In the last of these they are pre- 
sent in the interstratified bands of crystalline limestone, characteristic 
of this formation in Canada. 
With a few exceptions nearly all occur in limestone rocks, and 
their origin has depended upon various causes. The first fourteen, 
which compose the first division, enumerated in a previous part of 
this paper, are the results of aqueous action, as their situation, present 
condition, and general description clearly prove. Perhaps an ex- 
ception might be taken to the formation of pilasters and gothic 
arched recesses, which are more properly attributable to atmospheric 
influences. Volcanic agency has given origin to the basaltic dykes 
of Mecattina (17), the basalt of Henley Island (16), Bouchette's 
(19), and Gibb's (20) caverns. The same cause has most likely in- 
fluenced the subterraneous passages of Manitoulin (28), and MuiTay's 
Cavern (29). On the other hand, Bigsby's Cavern (18), Colqu- 
houn's (22), the Mono and Eramosa (25 and 26), and Bass Island's 
Caverns (27) were formed by some other agency, in which a slow 
disintegration of the rocks has occurred from chemical and other 
causes, and the soluble particles have been removed by the influence 
of water, entering by percolation from above, or between the neigh- 
bouring layers of rock. The origin of the Quartz Cavern, by the ex- 
plosion of a pyritous vein (23), is clear enough. 
It would be premature to enter at further length into the con- 
sideration of the formation of these caverns until farther evidence 
has been obtained. It is hoped, however, that this first attempt to 
embody a descriptive and connected account of the caverns of 
Canada in a single paper will be productive of ultimate good results 
to science, by stimulating the zeal of those on the spot to carry out 
by further exploration an earnest investigation of this interesting 
subject, for there is still much to be done to render it complete. 
Many of the caverns are systematically noticed and described for the 
first time ; and before this memoir was written, the inhabitants of 
that country were hardly aware that any caverns existed at all, except 
the comparatively few residing in the immediate neighbourhood of 
their presence. 
