102 
M'mes and Mineral Sialistics, 
colatinf^ tliroiigli tliein, and tlion as iho fissxiro fjradiially became 
larger and Jarijer the A'olume of -water likewise increased until tlie 
fissure became concerted into a true underground river or -watercourse. 
Even in cases -where no water ilows tlirough them at the present day 
it can plainly be seen that sucli w'as tlio case once, as exemplified in 
the caves or “ s-wallow-lioles” of Yorkshire, the Kalavothra of the 
Morea, South Australia, and many other parts. 
These caves arc eaten out of the limestone the solvent po-wer 
-which -water charged with carbonic acid possesses. Ordinary -water 
free from carbonic acid -vvonld be quite incapable of dissolving out the 
limestone, but all natural waters contain more or less of that gas, 
derived by the rain from the atmosphere as it falls and from the 
decaying vegetable matter which it meets with in its i>assago through 
the soil. 
All limestone eaves usually retain more or less completely their 
original form of fissures, expanded, perltaps, in parts into vast caves 
and chambers of immense pro]iortions, but again contracting a little 
further on into a mere crack or tunnel. 
Comparatively large rivers are received hy siieli caves, which then 
continue their course under ground, in some cases suddenly appearing 
to the light of day again, luit in otliers making their way beneath the 
surface right out to sea. Certain of the South Australian creeks are 
thus discharged. 
I do not refer to this subject of caves in limestone so much on 
accoixnt of tlie supposed one at ’VS'allerawang — for it may quite likely 
be proved to be merely the beginning of one — as to draw^ attention to 
the occnrrenco of such apertures in limestone districts, in order that 
they may be properly investigated. 
In conclusion, I think I may safely say that fliis portion of the dis- 
trict of Wallerawang seems to be destined to he one of tlie greatest 
and most flourishing portions of the Colony. IFore, w-ithin a comjxara- 
tively small circle of some four miles diameter, there az'e extensive and 
rich deposits of iron ores, coal, and abundance of limestone. At pre- 
sent nothing beyond exploratory work has been done with them; but 
as the A\allerawang Iron and Coal Company has taken up large selec- 
tions of the lands for the purpose of erecting iron works, there is a 
prospect that in a short time an attempt may bo made to utilize some 
of this great wealth. 
The -u'Jiole of the district along the western line, near to and beyond 
Hartley, is one of exceeding interest to the geologist from a purely 
scientific point of view', quite apart from llic importance and actual 
intrinsic value of the various nimoral deposits which it contains. 
It is a .source of great gratification to all who take any interest in 
these matters that, at last, the resources of this and otlicr portions of 
Hew South Wales stand a fair chance of being thoroughly and properly 
examined, now that tlic first step towards liaving a geological survey 
of the country has been taken by the Government — a stej) which may 
be regarded as an earnest of somelliing to follow 07i a more compre- 
hensive and extended basis ; for of course it is utterly impossible for 
any one geologist, however great his attainments, to make single- 
handed a finished survey of a country like this. 
