Cave Regions of the Ozarks and Black Hills | Page 3

those best acquainted with the Cave, at one hundred and
fifty miles; say that the average width and height of these passages
amount to seven yards each way, which is perhaps near the truth; this
would give upwards of twelve million cubic yards of cavernous space

which has been excavated through the agency of calcareous waters and
atmospheric vicissitudes."
Page 169: "On the south side of Green River the platform of limestone
forming the descent into Mammoth Cave is two hundred and thirty-two
feet above Green River."
"The entrance to the cave, being thirty-eight feet lower than this bed of
limestone, is one hundred and ninety-four feet above Green River. In
the above two hundred and thirty-two feet there are several heavy
masses of sandstone, viz.: at one hundred and twenty-five, one hundred
and forty-five, one hundred and fifty, one hundred and sixty and two
hundred and fifteen feet, but it is probable that most of these have
tumbled from higher positions in the hill, as no alterations of sandstone
have been observed at these levels in the cave. From an elevation of
from two hundred and forty to two hundred and fifty feet, the prevalent
rock is sandstone without pebbles, which can be seen extending up to
three hundred and twelve feet to the foundation of the Cave Hotel. The
united thickness of the limestone beds on this part of Green River, is
about two hundred and thirty feet, capped with eighty feet of sandstone.
About midway of the section on this part of Green River, are
limestones of an obscure oolitic structure, but no true oolite was
observed. Many of these limestones are of such composition as to be
acted on freely by the elements of the atmosphere, which, in the form
of nitric acid, combine with the earthy and alkaline bases of calcareous
rock, and give rise to the formation of nitrates with the liberation of
carbonic acid; hence the disintegrated rubbish of the caves yields
nitrate of potash after being treated with the ley of ashes and
subsequent evaporation of the saline lixivium. The wonderfully
cavernous character of the subcarboniferous limestones of the Green
River valley, and, indeed, of these particular members of the
subcarboniferous group throughout a great part of its range in Kentucky
and Indiana, is due in a great measure to this cause, together with the
solvent and eroding effects of water charged with carbonic acid. The
'rock-houses' frequently encountered both in this formation and in the
limestones of Silurian date, are produced by similar causes; the more
easily disintegrated beds gradually crumbling away, while the more

durable remain in overhanging ledges. By the oxidation of other
elements, sulphates of oxide of iron and alkalies result, which, by
double decomposition, with carbonate of lime, give rise to the
formation of gypsums which appears in the form of rosettes, festoons
and various other imitative forms on the walls and ceilings of the caves.
Crystallizations of sulphate of soda and sulphate of magnesia are not
uncommon, both in some of the caves and in sheltered situations under
shelving rocks."
The explanations thus given of the excavation and subsequent refilling
and decoration of the limestone caves of Kentucky and Indiana apply
equally well to those of other states; but it is to be remembered that at
the time of Dr. Owen's report, onyx, the most beautiful and valuable of
dripstones, had not yet been discovered in the United States; while now
especially fine deposits are known in California, Utah, Missouri, South
Dakota and Arkansas; the Missouri supply being exceptionally valuable
on account of the marvelous delicacy and beauty of its coloring; nor
can it soon be exhausted, as deposits have been found in eight counties
and further exploration will no doubt discover more.
Concerning the Subcarboniferous, or Mississippian Series in
Part I.,
Vol. IV., Missouri Geological Survey, Dr. C.R. Keyes says: "In the
great interior basin of the Mississippi the basal series is exposed more
or less continuously over broad areas, extending from northern Iowa to
Alabama, and from Ohio to Mexico."
While this broadly extended series of limestone is honey-combed in
many places and all directions by wonderful caverns, those of the
Ozark regions in Missouri, although comparatively little known, are
well worth knowing, and are possibly the most ancient limestone caves
in the world. Of the region in which they occur, Dr. Keyes, in the
volume last quoted, says: "The chief typographical feature of the state
has long been known in the Ozark uplift, a broad plateau with gentle
quaquaversal slopes rising to a height of more than one thousand five

hundred feet above mean tide, and extending almost entirely across the
southern part of the district. On all sides the borders of this highland
area are deeply grooved by numberless streams flowing in narrow
gorges. Against