1872, he found that the pavement in the three holes lay at depths of 63 4,
10 and 111 2 inches beneath the surrounding turf-covered surface. The old
guardian asserted that he was often forced to remove worm-castings from
the pavement; and that he had done so about six months before. My son
collected all from one of the holes, the area of which was 5.32 square
feet, and they weighed 7.97 ounces. Assuming that this amount had
accumulated in six months, the accumulation during a year on a square
yard would be 1.68 pounds, which, though a large amount, is very small
compared with what, as we have seen, is often ejected on fields and
commons. When I visited the abbey on June 22, 1877, the old man said
that he had cleared out the holes about a month before, but a good many
castings had since been ejected. I suspect that he imagined that he
swept the pavements oftener than he really did, for the conditions were
in several respects very unfavourable for the accumulation of even a
moderate amount of castings. The tiles are rather large, viz., about 51 2
inches square, and the mortar between them was in most places sound, so
that the worms were able to bring up earth from below only at certain
points. The tiles rested on a bed of concrete, and the castings in
consequence consisted in large part (viz., in the proportion of 19 to 33)
of particles of mortar, grains of sand, little fragments of rock, bricks
or tile; and such substances could hardly be agreeable, and certainly not
nutritious, to worms.
My son dug holes in several places within the former walls of the abbey,
at a distance of several yards from the above described bricked squares.
He did not find any tiles, though these are known to occur in some other
parts, but he came in one spot to concrete on which tiles had once
rested. The fine mould beneath the turf on the sides of the several
holes, varied in thickness from only 2 to 23 4 inches, and this rested on a
layer from 83 4 to above 11 inches in thickness, consisting of fragments of
mortar and stone-rubbish with the interstices compactly filled up with
black mould. In the surrounding field, at a distance of 20 yards from
the abbey, the fine vegetable mould was 11 inches thick.
We may conclude from these facts that when the abbey was destroyed and
the stones removed, a layer of rubbish was left over the whole surface,
and that as soon as the worms were able to penetrate the decayed concrete
and the joints between the tiles, they slowly filled up the interstices
in the overlying rubbish with their castings, which were afterwards
accumulated to a thickness of nearly three inches over the whole surface.
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