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The Rev. Mr. Zincke informs me that he has lately had an orchard
dug to the unusual depth of 4 feet. The upper 18 inches consisted
of dark-coloured vegetable mould, and the next 18 inches of sandy
loam, containing in the lower part many rolled pieces of sandstone,
with some bits of brick and tile, probably of Roman origin, as
remains of this period have been found close by. The sandy loam
rested on an indurated ferruginous pan of yellow clay, on the
surface of which two perfect celts were found. If, as seems
probable, the celts were originally left on the surface of the
land, they have since been covered up with earth 3 feet in
thickness, all of which has probably passed through the bodies of
worms, excepting the stones which may have been scattered on the
surface at different times, together with manure or by other means.
It is difficult otherwise to understand the source of the 18 inches
of sandy loam, which differed from the overlying dark vegetable
mould, after both had been burnt, only in being of a brighter red
colour, and in not being quite so fine-grained. But on this view
we must suppose that the carbon in vegetable mould, when it lies at
some little depth beneath the surface and does not continually
receive decaying vegetable matter from above, loses its dark colour
in the course of centuries; but whether this is probable I do not
know.
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