less than half an inch, and the mould, which did not contain any stones,
21 2 inches in thickness. Beneath this lay coarse clayey earth full of
flints, like that in any of the neighbouring ploughed fields. This
coarse earth easily fell apart from the overlying mould when a spit was
lifted up. The average rate of accumulation of the mould during the
whole thirty years was only .083 inch per year (i.e., nearly one inch in
twelve years); but the rate must have been much slower at first, and
afterwards considerably quicker.
The transformation in the appearance of this field, which had been
effected beneath my eyes, was afterwards rendered the more striking, when
I examined in Knole Park a dense forest of lofty beech-trees, beneath
which nothing grew. Here the ground was thickly strewed with large naked
stones, and worm-castings were almost wholly absent. Obscure lines and
irregularities on the surface indicated that the land had been cultivated
some centuries ago. It is probable that a thick wood of young
beech-trees sprung up so quickly, that time enough was not allowed for
worms to cover up the stones with their castings, before the site became
unfitted for their existence. Anyhow the contrast between the state of
the now miscalled stony field, well stocked with worms, and the present
state of the ground beneath the old beech-trees in Knole Park, where
worms appeared to be absent, was striking.
A narrow path running across part of my lawn was paved in 1843 with small
flagstones, set edgeways; but worms threw up many castings and weeds grew
thickly between them. During several years the path was weeded and
swept; but ultimately the weeds and worms prevailed, and the gardener
ceased to sweep, merely mowing off the weeds, as often as the lawn was
mowed. The path soon became almost covered up, and after several years
no trace of it was left. On removing, in 1877, the thin overlying layer
of turf, the small flag-stones, all in their proper places, were found
covered by an inch of fine mould.
Two recently published accounts of substances strewed on the surface of
pasture-land, having become buried through the action of worms, may be
here noticed. The Rev. H. C. Key had a ditch cut in a field, over which
coal-ashes had been spread, as it was believed, eighteen years before;
and on the clean-cut perpendicular sides of the ditch, at a depth of at
least seven inches, there could be seen, for a length of 60 yards, a
distinct, very even, narrow line of coal-ashes, mixed with small coal,
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