From G. H. Darwin 30 December 1871
Dec. 30. 71
A grass field betw. Leaves Green & the Salt Box house on the right hand of the road is marked with ridge & furrow.1 The field contains the end of a small valley where it quite dies out, so that the land is somewhat in the shape of a shallow spoon;—the furrows run parallel to the main line of the small valley ie parallel to the handle of the spoon.— Horace2 & I attempted to find the depth of the soil above the flints in the steepest part where the furrows ran transversly to the hill by probing with a stick I probed in the furrows & he on the ridges about 10 or 15 times each & then I found that the average distances of the flints below the surface on the furrows & ridges were about 5 inches & 3 inches respectively. We excluded the cases in wh. the stick obviously missed the flints & went in deep.— We tried the same thing in a part of the field which was nearly flat & found the depth below the furrows & ridges to be about 4 inches & 3 inches respectively.— The furrows appeared slightly more filled up on the hill side than on the flat There were a good many earth castings about tho’ I shd. say that they were by no means very numerous
G H D
Varying depth of top-soil in a ridge-and-furrow field with a depression.
Please cite as
Darwin Correspondence Project, “Letter no. 8124,” accessed on 19 February 2017, http://www.darwinproject.ac.uk/DCP-LETT-8124