书城公版The Formation of Vegetable Mould
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第44章

4.Summit of field, trench 45 inches deep (40)5.Close to summit of field, trench 36 inches deep (26)6.Close to summit of field, trench 28 inches deep (28)7.Near summit of field, trench 36 inches deep (24)8.Near summit of field, trench at one end 39 inches deep; the mould here graduated into the underlying undisturbed sand, and its thickness (24 inches) is somewhat arbitrary.At the other end of the trench, a causeway was encountered at a depth of only 7 inches, and the mould was here only 7 inches thick (24)9.Trench close to the last, 28 inches in depth (24)10.Lower part of same field, trench 30 inches deep (15)11.Lower part of same field, trench 31 inches deep (17)12.Lower part of same field, trench 36 inches deep, at which depth undisturbed sand was reached (28)13.In another part of same field, trench 9.5 inches deep stopped by concrete (9.5)14.In another part of same field, trench 9 inches deep, stopped by concrete (9)15.In another part of the same field, trench 24 inches deep, when sand was reached (16)16.In another part of same field, trench 30 inches deep, when stones were reached; at one end of the trench mould 12 inches, at the other end 14 inches thick (13)Small field between "Old Works" and "Shop Leasows," I believe nearly as high as the upper part of the latter field.

17.Trench 26 inches deep (24)

18.Trench 10 inches deep, and then came upon a causeway (10)19.Trench 34 inches deep (30)

20.Trench 31 inches deep (31)

Field on the western side of the space enclosed within the old walls.

21.Trench 28 inches deep, when undisturbed sand was reached (16)22.Trench 29 inches deep, when undisturbed sand was reached (15)23.Trench 14 inches deep, and then came upon a building (14)Dr.Johnson distinguished as mould the earth which differed, more or less abruptly, in its dark colour and in its texture from the underlying sand or rubble.In the specimens sent to me, the mould resembled that which lies immediately beneath the turf in old pasture-land, excepting that it often contained small stones, too large to have passed through the bodiesof worms.But the trenches above described were dug in fields, none of which were in pasture, and all had been long cultivated.Bearing in mind the remarks made in reference to Silchester on the effects of long- continued culture, combined with the action of worms in bringing up the finer particles to the surface, the mould, as so designated by Dr.Johnson, seems fairly well to deserve its name.Its thickness, where there was no causeway, floor or walls beneath, was greater than has been elsewhere observed, namely, in many places above 2 ft., and in one spot above 3 ft.The mould was thickest on and close to the nearly level summit of the field called "Shop Leasows," and in a small adjoining field, which, as I believe, is of nearly the same height.One side of the former field slopes at an angle of rather above 2 degrees, and I should have expected that the mould, from being washed down during heavy rain, would have been thicker in the lower than in the upper part; but this was not the case in two out of the three trenches here dug.