central portion suddenly dipped
to the north and to the east shortly before reaching the corner of the
west wall. Attempts to follow it downward were frustrated by black
earth, which when dug with pick or shovel assumed the consistency of
"hog-wallow mud."

For a space of 4 or 5 feet inside the doorway, whose floor was about 3
feet higher than the average surface level in the cave, the ashes were
not more than a foot thick, the clay rising to this extent. It spread
out fan shape, with a continuous slope for several yards in every
direction, thus making an easy grade for entrance and exit.

There are three ways in which this condition could have been brought
about.

First, the aborigines may have constructed a graded way; though it is
not at all likely they would have piled the clay so far to each side.

Secondly, it may have washed through the doorway from the outer cave
when the main outlet of the latter in the face of the bluff toward D
(fig. 13) was obstructed in some way. This is improbable.

Thirdly, it may be due to material deposited in the eddy or swirl
created by the corner of the west wall whenever a large volume of
drainage water flowed from the westward in the main cave and was
sharply deflected toward the south when it struck the east wall. This
is no doubt the correct explanation.

Whether or not these floods had any part in piling up the clay at the
doorway, beyond doubt it was to them that the clay, gravel, and sand
resting upon the floor of the main cave owe their origin. To them is
likewise due the dark earth overlying the clay at the rear and
covering the floor of the recess in the east wall. Clearly, there was
at one time in the cave's history a current at intervals, which
carried mud and small rocks from the interior of the cave, or from the
outside surface through sink holes, and left at least a part of it
where the velocity of the stream was checked. Later, much of this
water found other drainage channels, and the coarser matter could no
longer be carried into the cave; but at times of unusually heavy
precipitation enough of the torrent followed the old course to bring
in the dark earth. The last is due to top soil containing a large
amount of humus from decaying vegetation. Finally, no more water came
this way except as seepage, which is the condition at present.

[Illustration: FIG. 17.--Clay pipe from Miller's Cave.]

The pool at the rear may be entirely empty in dry seasons; and afte