surface.
[Picture: Fig. 5: Section of the vegetable mould in a field. Fig. 6:
Traverse section across a large stone]
A piece of waste, swampy land was enclosed, drained, ploughed, harrowed
and thickly covered in the year 1822 with burnt marl and cinders. It was
sowed with grass seeds, and now supports a tolerably good but coarse
pasture. Holes were dug in this field in 1837, or 15 years after its
reclamation, and we see in the accompanying diagram (Fig. 5), reduced to
half of the natural scale, that the turf was 1 2 inch thick, beneath which
there was a layer of vegetable mould 21 2 inches thick. This layer did not
contain fragments of any kind; but beneath it there was a layer of mould,
11 2 inch in thickness, full of fragments of burnt marl, conspicuous from
their red colour, one of which near the bottom was an inch in length; and
other fragments of coal-cinders together with a few white quartz pebbles.
Beneath this layer and at a depth of 41 2 inches from the surface, the
original black, peaty, sandy soil with a few quartz pebbles was
encountered. Here therefore the fragments of burnt marl and cinders had
been covered in the course of 15 years by a layer of fine vegetable
mould, only 21 2 inches in thickness, excluding the turf. Six and a half
years subsequently this field was re-examined, and the fragments were now
found at from 4 to 5 inches beneath the surface. So that in this
interval of 61 2 years, about 11 2 inch of mould had been added to the
superficial layer. I am surprised that a greater quantity had not been
brought up during the whole 211 2 years, for in the closely underlying
black, peaty soil there were many worms. It is, however, probable that
formerly, whilst the land remained poor, worms were scanty; and the mould
would then have accumulated slowly. The average annual increase of
thickness for the whole period is 0.19 of an inch.
Two other cases are worth recording. In the spring of 1835, a field,
which had long existed as poor pasture and was so swampy that it trembled
slightly when stamped on, was thickly covered with red sand so that the
whole surface appeared at first bright red. When holes were dug in this
field after an interval of about 21 2 years, the sand formed a layer at a
depth of 3 4 in. beneath the surface. In 1842 (i.e., 7 years after the
sand had been laid on) fresh holes were dug, and now the red sand formed
a distinct layer, 2 inches beneath the surface, or 11 2 inch beneath the
turf; so that on an average, 0.21 inch of mould had been annually brought
60