red with the dumped ashes.

At 18 feet from the mouth the rocks became larger and so numerous as
to be almost in contact, projecting above the ashes and imbedded in
the clay down to bedrock; they extended for 22 feet farther in and to
within 14 feet of the west wall. The clay attained its highest level
at the beginning of this pile of rocks, having an elevation of 9 feet
above bedrock; it became lower toward the interior, with its surface
everywhere rough and irregular.

The rocks were too large to be either moved or broken up, and owing to
the condition of the roof an attempt to reduce them by blasting would
have been attended with great danger, so they were perforce left in
place and as much as possible of the clay between and under them dug
away. Beyond those near the front, others, not reaching the top, were
found one after another buried in the clay; owing to their constantly
increasing number, and to the inward slope of the east wall, the
limits of the excavation gradually narrowed, hampering the movements
of the workmen, and it was necessary to handle the earth two or even
three times to get it out of the way. There was growing risk, too, of
the projecting rocks splitting off or breaking out of the clay matrix.
As some of them weighed several tons, the danger became too imminent,
and efforts to continue along the bedrock had to cease.

Two other attempts were made to get to the bottom; one at 40 feet from
the mouth just beyond the large rocks on the surface, and one at 15
feet farther in. The last one started on an area 8 by 15 feet, which
would have been ample if the sides could have been carried down even
approximately straight. Neither of these efforts met with success, for
the same reason that led to the abandonment of the first one.

From here to the end, examinations were confined to the deposit of
ashes. The surface, except as it had been disturbed by relic hunters,
was practically level from wall to wall, but the depth varied with the
undulating top of the clay beneath. Where it was deepest, in the
central portion about 50 to 75 feet from the mouth, the deposit had a
thickness of 6 feet. From this it diminished to about 3 feet on the
sides, with an occasional thinner patch on a narrow shelf formed by a
ledge or a crevice. The average thickness was close to 41/2 feet, so the
amount was not far from 800 cubic yards. This was composed entirely of
ashes from small fires for cooking, heating, and lighting p