LOWER LEVELS
(LEVELS C & D)
The “Historic tour” and
“River Styx tour” allow visitors to examine Mammoth Cave's deeper passages at
levels C, D, E, and F. Access is via a descending narrow passage behind
Giant's Coffin in the Main Cave (= level B). The upper levels are the
oldest (the first ones to be dissolved out, when the water table was at a much
higher level). Below the level of the Main Cave, the passages get
progressively younger. Levels C and D are dissolved out in Ste. Genevieve
Limestone beds. Levels E and F are partially to entirely developed in the
next formation down - the St. Louis Limestone (mid-Meramecian Stage,
middle Middle Mississippian).
Levels deeper than the Main
Cave are usually accessed via Dante's Gateway, a narrow, descending passage
behind Giant's Coffin. It acted as a water drain for level B's Main Cave
long ago. Dante's Gateway brings you to the Wooden Bowl Room,
named after an artifact found here in early days, although some say the name is
in reference to the shape of the room.
Wooden Bowl Room (looking ~S) (above &
below) - these photos show the southern portion of the Wooden Bowl Room.
The room is ~rounded in plan view and has a moderately low ceiling. It is
situated at Mammoth Cave's level C.
The ceiling is limestones of
the Karnak Member (Ste. Genevieve Ls.), a unit which consists of oolitic and
fossiliferous limestones having some patches of sparry calcite. The walls
of the room expose the Spar Mountain Member (Ste. Genevieve Ls.), a unit having
dolostones/dolomitic limestones and sandy limestones.
The opening at the base of
the wall (called the Snake Hole) leads to Jessup Avenue, Flint Alley, and
Ganter Avenue, none of which have been publicly accessible since the
1940s. The Jessup, Flint, and Ganter cave passages have been considerably
defaced by prehistoric American Indians, late 1800s cave trail construction,
and by historic cave tours. All three passages have a relative abundance
of American Indian artifacts and other evidence of Indian activity, such as
gypsum & chert/flint “mining”. A prehistoric Indian latrine was
discovered by archaeologists in Ganter Avenue.
Wooden Bowl Room - level D is accessed by descending
these very steep stairs at the northeastern side of Wooden Bowl
Room. This descent goes through the Fredonia Member (Ste. Genevieve Ls.),
a unit which has a mix of micritic limestones, argillaceous limestones, oolitic
& fossiliferous limestones, and dolostones/dolomitic limestones. This
descent is called the Steeps of Time (also known as the Dog Hole).
The Steeps of Time ends in a
tubular, phreatic passage called Black Snake Avenue, developed at
Mammoth Cave's level D (upper level D).
Black Snake Avenue (looking ~N or ~NW) - the
ceiling and walls of this tubular passage are nicely scalloped for much of its
length. Scallops are dissolutional features formed at or below the
water table (in the phreatic zone). They vary from being scoop-shaped to
broadly ripple-shaped. They indicate dissolution in flowing water (an
underground river or stream). Flow direction was toward the steep side of
the scallops (= into the photo shown above). The rocks are part of the
Fredonia Member (Ste. Genevieve Ls.).
Black Snake Avenue - nice rills on Fredonia
Member limestones along the walls of Black Snake Avenue. Rills are
dissolutional features formed by water flowing down sloping rock faces in the
vadose zone (above the water table). As such, these rills postdate
the development of the passage and the scallops (both of which are
dissolutional phreatic features).
Black Snake Avenue - Fredonia Member rocks
with solution pockets in the lower part of the photo & rills
in the upper part of the photo.
Two significant domepits (aka
vertical shafts) are encountered along Black Snake Avenue - Sidesaddle Pit and
Bottomless Pit. Domepits appear to be pits when viewed from above,
and would be called domes if viewed from below. Hence the term “domepit”.
Domepits are dissolutional features formed in the vadose zone (above the water
table). They form as vertically-descending water dissolutionally enlarges
joints or joint intersections.
Sidesaddle Pit - Fredonia Member
limestones line the walls of this impressive domepit. The vertical
grooves seen on the walls of Sidesaddle Pit and Bottomless Pit (see below) are
called flutes. They are similar to rills (see above) by
also being dissolutional vadose features, but flutes are grooves on vertical
limestone walls, while rills are grooves on sloping limestone
walls. The rubble-covered floor of this domepit appears to bottom out in
the lower Ste. Genevieve Limestone (Fredonia Member) or the upper St. Louis
Limestone.
Bottomless Pit (from an old postcard;
original photograph by Benjamin Hains)
Bottomless Pit (above & below) - a
very deep domepit that bottoms out well into the St. Louis Limestone (the
lowest encountered stratigraphic unit in Mammoth Cave). The limestone
walls of the domepit are nicely fluted. The rocks seen here & below
are Fredonia Member limestones (Ste. Genevieve Ls.). Bottomless Pit used
to be a turn-around point for early tours. Later tours crawled along a
narrow edge. The domepit is now readily traversed via a metal trail
bridge.
This domepit does
have a bottom, despite the name. The rubble-covered floor of this domepit
is in the upper St. Louis Limestone. The floor closely coincides with the
level of the River Styx and the Echo River (the modern water table; aka
local base level).
Bottomless Pit
Black Snake Avenue between Bottomless Pit and
Winding Way continues to be a subhorizontal phreatic cave passage having an
ellipsoidal cross-section shape. This is still part of level D. The
rocks are Fredonia Member limestones (Ste. Genevieve Ls.).
Scotchman's Trap (from an old postcard) -
breakdown occurs at a small opening called Scotchman's Trap where Black Snake
Avenue descends a bit elevationally & stratigraphically.
One of the most famous
passages in Mammoth Cave is a quite narrow, tapering-downward, twisting canyon
passage called Winding Way. The park service uses the anti-male
sexist term “Fat Man's Misery” for this locality (in fact, objections to this
name have been made for over a century). Part of this stretch has also
been called “Tall Man's Agony” (uncomfortable stooping is necessary for tall
folks). Winding Way is developed in about the mid-Fredonia Member (Ste.
Genevieve Ls.).
Winding Way - this remarkable canyon
passage is about half-a-meter to a meter wide in the lower part (where people's
legs are). It's a bit wider in the upper part. In places, it's
about a meter-and-a-half tall. Notice the scallops along the limestone
walls.
Some claim that no one has
ever gotten stuck in this passage. Bullitt (1845) recounts the following:
“our fat friend, who was puffing and blowing behind us like a high pressure
engine, cried out, ‘Halt, ahead there! I am stuck as tight as a wedge in a log!’ Halt
we did [and we looked] at our friend, who was in truth ‘wedg’d in the rocky way
and sticking fast,’ . . . the imprisoned gentleman soon burst his bonds. . .
and at length forcing his way into Relief Hall, he cried out, in the joy of his
heart, while stretching himself and wiping the perspiration from his jolly,
rubicund face, ‘never was a name more appropriate given to any place - Relief.
. . I can now breathe again.’”
Winding Way was formed by
moderately fast-flowing water draining toward the old water table.
Winding Way ends at a
moderately large, subhorizontal phreatic passage called Great Relief Hall
(formerly known as Relief Hall). This passage is stratigraphically &
elevationally lower than Black Snake Avenue and Winding Way, but is still part
of Mammoth Cave's level D (= lower level D).
Great Relief Hall (looking WNW) - this is a
phreatic passage, formed at or below the old water table. Flow direction
of the underground river at that time was into the photo (toward the
WNW). The light gray rocks of the ceiling and upper walls are Fredonia
Member limestones. The darker rocks in the lower part of the walls are
Fredonia Member dolostones/dolomitic limestones. Notice the scallops
along the walls (the wavy sculpturing). Notice also chert nodules
protruding from the ceiling. Chert is composed of cryptocrystalline quartz.
So, it is highly resistant to weathering, erosion, and dissolution by slightly
acidic groundwater.
Chert nodule protruding from ceiling
limestones of the Fredonia Member (Ste. Genevieve Ls.) in Great Relief Hall
(lower part of Mammoth Cave's level D).
Ceiling smoke writing (above & below) -
Gothic Avenue is the not the only passage in Mammoth Cave that's been
considerably defaced. The ceiling of Great Relief Hall also has a fair
amount of smoke signatures. Note the 1839 and 1855 dates.
