openings. The largest is near the top of a knoll or
low hill, and is due to the falling in of the roof. The sunken part
has an area of about 30 by 60 feet. Usually, in such cases, the debris
entirely fills one end of the cavity thus made, obscuring that part of
the cavern, the other end being kept open by surface drainage. In this
case, owing to the dip of the strata--some 8 or 10 degrees--and to a
change in direction of the cavern at this point, both ends may be
entered from the fallen rocks and earth. At one side the descent is
precipitous and winding, over and among large fallen rocks. No level
place is reached in daylight. At the other side the descent follows
the natural dip of the strata and no level space can be found from
which the entrance is visible. This part, also, is filled with rocks,
large and small, from the roof and sides, and was never habitable.

Fifty yards from the main entrance is another much smaller cave, on
the slope of the knoll. It is at the bottom of a crevice 10 feet deep.
The floor is level, but only a few square yards in extent, the sloping
roof reaching it within 10 feet. As there is considerable drainage
into the cavity from the hillside, it is probable that this floor, at
least the upper portion, is of recent origin, and that the earth
extends downward indefinitely toward the subterranean stream.

West of the knoll on which these openings are found is a valley 2 or 3
miles long. Timber shuts off the view toward its head. This is
drained by a constant stream which after winding from side to side of
the little vale flows under the knoll. The hole where it disappears is
small, but as no rock floor is visible it may lead into a large
cavern, and there is no doubt that all the sink holes in the vicinity
as well as the two openings above described eventually have the same
outlet. Excavations would be difficult and useless.

THOMAS CAVE.--In the face of a steep hillside, near the south (left)
bank of the Holston, 3 miles east of Bluff City, is a room with a
nearly level floor 10 by 18 feet in the longest measurements. A narrow
passage, high enough for a man to walk in, branches off to the right
but soon begins to diminish in size and at 100 feet becomes too small
to crawl through. The debris in front of the cave is piled to a height
of 16 feet above the present floor, and the highest floods of the
river reach to about the same level on the outside. The rapid
disappearance of the surface wate