[UNDER-1 5 b.] Subsoil.
1707. Mortimer, Husb., 315. A Planter or Raiser of Trees ought to consider the under Soil, as well as the superficies of the Earth.
1863. Bates, Nat. Amazon, I. 25. The difference in colour from the superficial soil … is owing to their being formed of the undersoil, brought up from a considerable depth.
