This earth, however, is not to be ſuppoſed entirely pure, but is mixed with much ſtony and gravelly matter, from the layers lying immediately beneath it. It generally happens, that the ſoil is fertile in proportion to the quantity that this putrified mold bears to the gravelly mixture; and as the former predominates, ſo far is the vegetation upon it more luxuriant.
1791, Oliver Goldsmith, “Of the Internal Structure of the Earth”, in An History of the Earth, and Animated Nature. […], new edition, volume I, London: […] F[rancis] Wingrave, successor to Mr. [John] Nourse, […], page 49