in the stream through the middle passage.

The cavern is situated 31/2 miles east of Mitchell. It has been fitted
up by the State University as an experiment station for the study of
underground fauna and flora.

The branch to the right is never entirely dry. Throughout the year
water trickles or seeps over the stones and keeps the mud soft and
sloppy, while after extremely heavy rains the water may be 2 or 3
inches deep for a short time--enough to keep all the earth washed from
the floor for 50 or 60 feet from the entrance.

The northern or left branch presented a smooth, solid floor of rock at
the beginning. The roof is about 13 feet above the floor, being a flat
stratum broken by a joint-seam along which there is a slight fault. A
ledge of friable sandstone 31/2 feet thick lies next below the roof. The
disintegration of this gave a dry covering to the clayey earth which
covered the floor almost to the extreme edge of the rock overhanging
the stream and gradually rose toward the rear, where it entirely
filled the space from floor to roof. The distance between the side
walls is 8 feet at the mouth. They diverge slightly, and at 65 feet
are about 12 feet apart. Here they separate more sharply, forming a
chamber 30 feet in diameter, measuring on every side to the contact of
the earth and the roof. At the extreme rear a slight wash or
depression in the earth revealed the top of a vertical solid wall,
thus marking the limit of the cave in that direction. It seems,
however, to extend farther to the east and the west than it can now be
followed; in fact, the indications are that at one time a considerable
cross-cavern extended along this line.

The work of clearing out this branch began at the entrance. The
superincumbent earth was removed by a trench whose boundary was the
solid rock on each side until the cave widened to more than 8 feet
between the walls; then a width of 7 to 9 feet was excavated midway
between the sides, the entire trench having a length of 92 feet, or
reaching nearly to the vertical wall at the rear. For about 60 feet
the earth was removed to the rock floor. At this distance the floor
dipped. The bottom of the trench continued to follow the same level it
had held to this point, in the belief that the dip in the floor was
due to a crevice or slight erosion channel and would soon disappear,
bringing the rock to its normal position. This was not the case;
several holes were dug, the deepest one 3 feet