Finally, we may infer that a large part of the fine vegetable
mould, which covered the floor and the broken-down walls of this
villa, in some places to a thickness of 16 inches, was brought up
from below by worms. From facts hereafter to be given there can be
no doubt that some of the finest earth thus brought up will have
been washed down the sloping surface of the field during every
heavy shower of rain. If this had not occurred a greater amount of
mould would have accumulated over the ruins than that now present.
But beside the castings of worms and some earth brought up by
insects, and some accumulation of dust, much fine earth will have
been washed over the ruins from the upper parts of the field, since
it has been under cultivation; and from over the ruins to the lower
parts of the slope; the present thickness of the mould being the
resultant of these several agencies.
I may here append a modern instance of the sinking of a pavement,
communicated to me in 1871 by Mr. Ramsay, Director of the
Geological Survey of England. A passage without a roof, 7 feet in
length by 3 feet 2 inches in width, led from his house into the
garden, and was paved with slabs of Portland stone. Several of
these slabs were 16 inches square, others larger, and some a little
smaller.
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