Cave Regions of the Ozarks and Black Hills | Page 2

acidulated water on the
limestone, and its subsequent removal as the volume of surface
drainage diverted to the new channel gradually increased. But it is not
so easy to offer a reason for the varied forms with which the caves are
afterwards decorated. Why is it the charmed waters do not leave the
evidence of their slow passage only in plain surfaces of varying widths,
and the stalactites and stalagmites whose formation we can readily
account for? And why do not the deposits take the same forms in all
caves with only such variations as would naturally result from
differences in topography? The law is written, but in unfamiliar
characters that render our reading slow and uncertain. Yet it is

conspicuously noticeable that those caves showing the most delicately
fragile and wonderfully varied forms of decoration are those traversed
by the most sweeping and changeable, or even reversible, currents of
air; which might lead to the conclusion that the moisture is sprayed or
converted into a light, misty vapor, and then deposited in exactly the
same manner as the beautiful frost-work at Niagara: the direction and
force of the current determining the location of the frail deposits.
Since the largest and most important caves occur in limestone, a little
special attention to the cause of their occurrence there may serve to
show that although speleology has only recently received its name and
been elevated to the rank of a separate and independent science, it is
one of the earth's ancient institutions.
Our geologists, who have unearthed many secrets not dreamed of even
in Humboldt's "good phylosopy," have settled the question of how the
different kinds of caves were formed, according to the character of
rocks they are in, or their location and depth, and the natural agencies
to whose action they show signs of having been subjected.
Dr. H.C. Hovey, in his "Celebrated American Caverns," says: "In
visiting caves of large extent, one is at first inclined to regard the long
halls, huge rifts, deep pits and lofty domes, as evidences of great
convulsions of nature, whereby the earth has been violently rent
asunder. But, while mechanical forces have had their share in the work,
as has been shown, the main agent in every case has been the
comparatively gentle, invisible gas known as carbonic acid. This is
generated by the decay of animal and vegetable substances, and is to a
considerable degree soluble in water. Under ordinary circumstances
one measure of water will absorb one measure of carbonic acid; and the
eye will detect no difference in its appearance. Under pressure the
power of absorption is rapidly increased, until the water thus
surcharged has an acid taste, and effervesces on flowing from the earth,
as in Saratoga water.
"Rain-water, falling amid leaves and grass, and sinking into the soil,
absorbs large quantities of carbonic acid. On reaching the underlying
limestone, the latter is instantly attacked by the acidulated water in

which it is dissolved and carried away.
"It is agreed among geologists, amazing as the statement may seem,
that the immense caverns of Virginia, Kentucky and Indiana, including
Mammoth Cave itself (the largest of all), were eaten out of the solid
mass of limestone by the slow, patient, but irresistible action of
acidulated water."
Professor N.S. Shaler says: "The existence of deep caverns is a sign
that the region has long been above the sea."
Through the kindness of Professor C.J. Norwood, Chief Inspector and
Curator of the Geological Department of Kentucky, it is possible to
quote the first official report made on the caves of that state and
published in 1856, in Volume I., Kentucky Geological Survey Reports.
Dr. Norwood says: "Referring to the 'Subcarboniferous Limestone'
(now known as the St. Louis group of the Mississippian series), Dr.
Owen says: 'The southern belt of this formation is wonderfully
cavernous, especially in its upper beds, which being more argillaceous,
and impregnated with earths and alkalies, are disposed to produce salts,
which oozing through the pores of the stone effloresce on its surface,
and thus tend to disintegrate and scale off, independent of the solvent
effects of the carbonated water. Beneath overhanging ledges of
limestone, quantities of fine earthy rubbish can be seen, weathered off
from such causes. In these I have detected sulphate of lime, sulphate of
magnesia, nitrate of lime, and occasionally sulphate of soda. The
tendency which some calcareous rocks have to produce nitrate of lime
is, probably, one of the greatest causes of disintegration.'"
"Most extensive subterranean areas thus have been excavated or
undermined in Edmonson, Hart, Grayson, Butler, Logan, Todd,
Christian and Trig. In the vicinity of Green River, in the first of these
counties, the known avenues of the Mammoth Cave amount to two
hundred and twenty-three, the united length of the whole being
estimated, by