164 
BULLETIN OF THE NATURAL HISTORY SOCIETY. 
in the month of Tnly, and one immediately in rear of my house 
at ]\larkhamville, which is a narrow slit in the rock, into which 
a boy can crawl fifty feet or more, delivers a small stream of pure 
ice-cold water all the year round, the volume of which is not 
much affected by heavy rains. The hill above it rises probably 
200 feet in 500 yards.” 
This is not the place in which to discuss at length the origin 
of manganese beds, but the observations of Col. Alarkham seem 
to point strongly to the conclusion that they are residual deposits, 
not conveyed to their present site by the action of solvent waters, 
thus filling up pre-existing caverns, but left in a concentrated 
condition by the removal, through solution, of the limestone beds 
originally containing them, a process similar to that by which 
large beds of ferriferous dolomite have in some parts of the world 
become replaced by extensive deposits of limonite. 
I am not aware of the existence of any noticeable caves or 
cavities in the limestones of the Silurian system. The fact, 
however, observed at Grand Falls, that a stream of considerable 
volume discharges into the gorge from the face of the cliff, only 
a few yards below the face of the cataract, indicates that, where 
circumstances are favorable to their production, subterranean 
channels exist. 
In the pre-Cambrian limestones and dolomites of St. John 
and Charlotte counties, cavities of small size have been frecpiently 
laid open in the course of quarrying operations. At other points 
indications of subterranean cavities are to be found in the hollow 
sound beneath the tread of the feet, or the fact, illustrated in some 
of the limestone hills about Trookville, that holes exist in which, 
if stones l:e introduced, these may be found, as indicated by the 
sound, to drop for considerable distance before striking bottom. 
Prof. Ganong informs me that, as a boy. he was acquainted with 
a good cave in the rear of Lily Lake, near St. John, the dimensions 
of which he cannot now recall. P)Ut probably the most interest- 
ing excavation occurring in these limestones is that of Oliver’s 
cave, so-called on the Sandy Point road, about two miles from 
