Audubon County journal. (Exira, Iowa) 1884-1993, 1898-04-28
UNDERGROUND STREAMS.
There Are Thousands of Miles of Subter-
ranean Rivers In Kentucky.

Oh "The Mammoth Cave of Ken
lucky" Mr.. Proctor says:
Passing southwark through Ken
lucky on the Louisville and Nash
vile railway the observant traveller
will notice that about 40 miles from
the road climbs Null
drow's hill, which is the northern
escarpment of an elevated limestone
plateau sloping gently to the south
and west. The road traverses this
plateau for about 100 miles and de-
sends a southern escarpment into
the basin of central Tennessee. In
this distance only three streams are
crossed-Nolin, Green and Barren
rivers-and between these rivers the
entire surface drainage passes away
through subterranean channels, CIV
ing rise to a curious sink hole
topography which is peculiar to this
region. These circular and oval
shaped depressions are so numerous
that in places the rims almost touch |
one another, and one can sometimes
count several hundred to the square
mile. Through vents at the bottom
of these sinks the surface water
passes downward into caverns and
underground streams, emptying into
the above named rivers through
arched ways near water level and in
places beneath the surface of the
rivers.
The surface rock of this plateau
is the subcarboniferous limestone,
which is here several hundred feet
thick, a massive, remarkably homo
geneous rock, with no intervening
strata of shale OF sandstone, condi-
tons most favorable for the forma-
ton of caverns. Consequently this
region contains more and larger
caves in given area than any other
region in the world In Edmonson
county, where the celebrated Nam
moth cave is located, it is claimed
that there are as many as 5OOknown
cavernS.
A range of hills of uniform height,
running parallel with the railway
and several miles distant, will be
observed to the north. On nearer
inspection this will be seen to be
level plateau rising out OF the lime
stone plain and held up by cap
ping of massive sandstone. 1t is
beneath the protection of this sand
stone capped plateau that the larger
caves are found. Green river has
cut through this plateau to depth
of about 800 feet, and as the sand
stone cap is about 70 feet thick we
find about $50 feet of massive lime
stone exposed above the drainage
level. AS some of the domes and
upper avenues of the caves extend
up to the base of the sandstone and
some down to the drainage level we
thus have $50 feet as the present
limit of the vertical extension of
these caves. The evidence is con-
elusive that these caves have been
cut down to correspond with the
deepening of the channel cut by
Green river. In the region imme-
diately along the line of the rail
way, where the sandstone Gaping
and the upper limestone have been
removed by erosion, the caverns
have less vertical extension and cor
respond to the lower avenues of the
Mammoth and other caves to the
north. Doubtless large caverns, COR
responding to those now remaining
beneath the sandstone plateau exist
ed here before the upper member of
the limestone was eroded from this
area.
There is no means of estimating
the extent of the caverns and sub
terranean streams in this region.
Every one of the innumerable de-
pressions, OF sink holes-save where
the vents have been closed, thus
forming ponds-communicates with
an underground channel OF cave,
and the aggregate length of such
channels has been estimated at
many thousands of miles. Nor can
we form any estimate of the num-
Der and extent OF large caverns yet
undiscovered. But for the erosion
caused by a small stream cutting
through the roof of Mammoth cave
the present entrance would not have
been broken open, and this, the
greatest of caves, might have re-
manned unknown. Several other of
the largest and most beautiful caves
in this region have been found by
accident. Hidden grandeurs doubt.
less yet remain entombed beneath
the extensive uplands reaching out
on both sides of Green river.
In crossing the southern upland
we come upon oval shaped limestone
valleys, surrounded on all sides by
sandstone rim, with no outlet save
through vents in the bottom. These
valleys are sometimes hundreds OF